DEVELOPMENTAL PATTERNS AND YIELDS OF WHEAT (TRITICtlM ASETIVUM L .) by

DEVELOPMENTAL PATTERNS AND YIELDS OF WHEAT (TRITICtlM ASETIVUM L .) by

DEVELOPMENTAL PATTERNS AND YIELDS

OF WHEAT (TRITICtlM ASETIVUM L .)

GROWN WITH MINIMAL WATER by

Gholam Hossein Sarmadnia

A Dissertation Submitted to the Faculty of the

•DEPARTMENT OF PLANT SCIENCES

\

In Partial Fulfillment of the Requirements

For the Degree of

DOCTOR OF PHILOSOPHY

WITH A MAJOR. IN AGRONOMY AND PLANT GENETICS

In the Graduate College

THE UNIVERSITY OF ARIZONA

:

1981

THE UNIVERSITY OF ARIZONA

GRADUATE COLLEGE

As members of the Final Examination Committee, we certify that we have read

the dissertation prepared by Gholam Hossein Sarmadnia________________________

entitled Developmental patterns and yields of wheat fTriticum Asetivum L.1 grown with minimal water_______________________________________________

and recommend that it be accepted as fulfilling the dissertation requirement

for the Degree of Doctor of Philosophy_________________________________________ .

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Final approval and acceptance of this dissertation is contingent upon the

candidate's submission of the final copy of the dissertation to the Graduate

C o l l e g e .

I hereby certify that I have read this dissertation prepared under my

direction and recommend that it be accepted as fulfilling the dissertation

r e q u i r e m e n t .

Dissertation Director

D a t e U

v

STATEMENT 3Y AUTHOR

This dissertation has been submitted in partial fulfillment of

the requirements for an advance degree at The University of Arizona.

It has been deposited in the University Library to be made available

to borrowers under the rules of the Library.

Brief quotations from this dissertation are allowed without

source is made. Requests for permission for extended quotation from

or reproduction of this manuscript in whole or in part may be granted

by the Head of the major department or the Dean of the Graduate

College, in his judgement the proposed use of the material is in the

interests of scholarship. In all other instances, however, permission

must be obtained from the author.

SIGNED:---

ACKNOWLEDGMENTS

I wish to express my deep gratitude to Dr,. Kaoru Matsuda, .His

inspiration and close guidance throughout the study period, and his

assistance and counsel during the planning and the preparation of the

experiments as well as the writing of this manuscript are deeply

appreciated,

I would like to express my sincere gratitude for the extensive

support during the course of graduate study and indepth review, of the

manuscript, rendered by Dr, Brooks Taylor, Dr. Paul Bartels, Dr. Robert

Briggs and Dr. Lee Stith.

financial assistance during the experiment which made this study

possible.

I am also grateful to Dr. Tom Ramage and Mr. Rex Thompson for

field assistance, constructive advice and providing spring wheat used

for this study.

The author chooses to identify Gideon Adjei and.Ardeshir Riazi

for competent cooperation in the field and laboratory studies.

motivating force without which little could be accomplished. 'This

undertaking proves to. be no exception, therefore, it gives the author

the honor to recognize his loving and accomplished wife, Sima,, as his

inner source..

TABLE OF CONTENTS

LIST OF TABLES . . vi

LIST OF ILLUSTRATIONS . . ... . . . . .. . . . , .

ABSTRACT . . xii

INTRODUCTION . . . . . . . . . . . ... . . .

REVIEW OF LITERATURE . . . . ... . . . . . . . .

1.

3

Effect of Water Stress on Physiological Processes . . . .

3

Growth Stages of Cereal Crops

Leaf

. . . . . . . . . .

. . . .

3

5

Water Stress and Photosynthesis . . . . . . . . .

Translocation

New Formed Assimilates . . . . . . . . . . . . . 10

Mobilization and Distribution of Stored Reserves . . . 11

Effect of Water Stress at Different Stages of Development

6

8 on Grain Yield . . . . . . . . . . . . , . 12

Emergence to Jointing .

.

.

.

.

.

.

.

.

.

.

14

Jointing to Heading .

.

.

.

.

.

.

.

.

.

.

14

Heading to Soft Ripe .

.

.

.

.

.

.

.

.

.

15

Soft Ripe to Maturity . . . . , . . . . . .

Summary of Pertinent Literature . . . . , . . . . .

15

17

MATERIALS AND METHODS . . . . . . . . . . . . . 19

Identification Of Seed Sources . . . . . . . . . 19

Field Design . . ................... . . . 19

Experiment I: Dryland Wheat Yield Test (Mesa 1978-1979) 24

Experiment II: Dry land Wheat Yield Test (Mesa 1979-1980) 24

Critical Irrigation Period, Tucson, 1979-1980) .

Sampling for Developmental and Morphological Studies .

. 25

27

Handling of Harvest Data . . . . . . . . . ... 28

Measurement of Plant Water Status and Growth" . . . . 29

RESULTS AND DISCUSSIONS ... . . . . . . . . . . . 30

Growth and Yield of Wheat Under Limited Moisture

Conditions, Mesa, Arizona, 1978-1979. . . . . . , 30

Crop Growth Analysis . . . . . .

Growth and Yield of Wheat under Limited Moisture

Mesa, Arizona, . . , , . , 44

Crop Growth Analysis . . . , . . . . . iv

V

TABLE OF CONTENTS— Continued

Growth and Yield of Wheat under Different Irrigation

Regimes, Tucson, Gasa Grande Overpass Farm:, 1979-1980 , '

5k

Crop Growth Analysis . , » » .

, . . , .. 69

Grande Overpass Farm,-1979-1930 . . .

Leaf Expansion Growth „ . • ■ . ..

, , , . 84

. . . 96

SUMMARY AMD CONCLUSIONS' , . . , . ... . . . .

. 99

LITERATURE CITED . . . . . . . . .

. . . . . . 105

LIST OF TABLES

Table Page

1. Entries and source used at Mesa during the 1973-1979, and

1979-1980 growing seasons , . . , . ... . 20

2. Listing of entries, seed sources of wheat, and time of irrigation for Experiment III conducted at the Casa

Grande Overpass Farm, Tucson, during the 1979-1980 .

growing season . . . , . , , . . . . . 21

3. Monthly precipitation at Mesa and at the Casa Grande

Overpass Experiment Station during the 1978-1979 and

1979-1980 growing seasons . . . . . ... .

.

.

, . 26 .

4. Yield.and Yield components of commercial and experimental wheat entries from Mesa, 1978-1979 .

. . . . . . 31

5. Correlation coefficients for yield and morophological.

Characters measured at different harvesting dates . . 33

6. Total above ground dry weights of commercial and

experimental lines of wheat at different dates in Mesa

(

1978-1979) growing season . . . . . ,

. . 37

7. Dry weights of heads and straw of commercial and experimental lines of wheat at.specified dates in .Mesa,

1978-1979 season

.. . . ... . . .

. . 38 .

8. Leaf area indicies of commercial and experimental lines in

Mesa, 1978—1979 . • . . . . .

. . . . . . ~. 39

9. Number, of green leaves and % of green leaves at designated days after anthesis in Mesa, 1978-1979 . . .. . . 40

I.0. Yield" (kg/ha) and yield components of commercial and experimental entries of wheat planted in Mesa, 1979-1980 45

II. Correlation Coefficients of yield, yield components and growth parameter measured in Mesa, 1979-1980 . . . , 46

12. Total above dry weights, of commercial'and experimental lines of wheat grown under ’dryland’ conditions in Mesa,

1979-1930 . . . . . , . . . . . . ; . . > .

50

13. Dry weights of heads and straws of commercial and experimental lines of vheat planted under ’dryland’ conditions, in Mesa, 1979-1930 . -.,. . . .

. 51

V I 1

LIST OF TABLES^— Continued

Table Page

14. Leaf area indicies of commercial and experimental entries of wheat on various dates in Mesa, .1979-1980 . . . . 53

15. Yield of commercial entries of wheat grown in Tucson under different irrigation regimes, .

.

.

.

.

.

.

55.

16. Yield components of commercial entries of wheat grown under different irrigation regimes in Tucson, 1979-1980 57

17. Correlation coefficients of various plant developmental

characters with yield and with each other when grown on

minimal water (150 kg/m^) . . . . . . . . . . ,

18. Correlation coefficients of various plant developmental

59

3/11 irrigation treatment (225 kg/m2 HpQ) , , t / / ■ §0

19. Correlation coefficients of various plant developmental

' characters with yield and with each other measured on

3/24 irrigation treatment (225 kg/m2 HpQ) . . . \ g-j

20.. Correlation coefficients of various plant developmental

characters with yield and with each other when grown on

well-watered conditions (525 kg/m^) , . . . . . 63

-21. Total above ground dry weights of commercial lines of viieat grown'under minimal water conditions .

.

.

.

.

.

.

73

22. Total above ground dry weights of commercial, lines of wheat

. 74

23. Total above ground dry weights of commercial lines of wheat which received irrigation on March 24 . . . . . . .75

24. Total above ground dry weights of commercial lines of wheat using, high level of irrigation . . . . . . . . 76

25. Dry weight of heads and straws of commercial lines of wheat grown under normal water conditions , . . . . . , 77

26. Dry weight of heads and straws of commercial lines of wheat

additional irrigation on March 11 . . . . . 78

Table ■ Page

27. Dry weight of heads and straws of commercial lines of wheat grown in Tucson and irrigated on March 24 . . . . , 7 9 v

2 8 . Total above ground dry weights of commercial lines of wheat

planted under well-irrigated 'control' conditions . . . . 80

29. Leaf ai^ea indicies of commercial entries of wheat planted at

Casa Grande Overpass Farm, 1979-1980 . . . . . . . 81

30. Tissue water potential ( ) , oanotic potential (ir), and

turgor pressure (p) of seven wheat varieties grown, under

'dryland' conditions at the Casa Grande Overpass Farm,

1980 .

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

.

85

31. Tissue water potential ( y

), osmotic potential (it), and

turgor pressure (p) of seven wheat varieties grown under

well-watered conditions at the Casa Grande Overpass Farm,

1980 *

» » » » » • » • » • » » • » * * * 86

32. The expansion of flag leaves on tillers of wheat plants . 98

LIST OF ILLUSTRATIONS

1. The moisture release curve for the soil at the Casa

Grande Overpass Farm. . .. . , .

2. Weight of individual grains from a head of a highyielding cultivar grown under 'dryland* condition

, 23 mOst basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain numbers of the head were

2,81 g, and 50 grains, respectively. . . . . . . 34

3. Weight of individual grains from a head of a low yielding

cultivar grown under 'dryland' conditions in Mesa

during the 1978-1979 growing.season, The most basal .

spikelets and most basal florets in a given spikelet

are designated as being number 1, Total grain weight

and grain numbers of the head were 1.63 g, and 46 grains,

respectively. . . ... . . ... . , , .. ... . -. 35

4. Weight of individual grains from a head of high yielding cultivar grown under ’dryland’ conditions in Mesa .

designated as being number T. Total grain weight and

.

, . * , * » - , , » » , * - » ■» 47

cultivar grown under ’dryland’ conditions in Mesa during

the 1979-1930 growing season. The most basal spikelets

and most basal florets in a given spikelet are designated

as being number 1. Total grain weight and grain numbers

of the head were.1.85 g and 43 grains, respectively.

6. Weight of individual grains from a head of high yielding

cultivar grown under ’dryland’ conditions at the Casa

.Grande Overpass Farm during the.1979-1980 growing season.

49

.spikelet are designated as. being number 1. Total weight :

and grain number of the head were 2.15 g and 60 grains,

respectively. , . . . • . , .

.

. .

7. Weight of individual grains from a head of low yielding ■

cultivar grown under ’3/11 irrigation treatment ’ conditions

.

.

64 ix

X

LIST OF ILLUSTRATIONS— Continued

Figure Page

a given spikelet are designated as being number 1. Total

grain weight and grain number of the head are 1.52 g, and

60 grains, respectively, .

. . . . . , . . .

8. Weight of individual grains from a head of high yielding

cultivar grown under 1 well irrigated' conditions at the

Casa Grande Overpass Farm during the 1979-1980. growing

-

season. The most basal spikelets and most basal florets

in a given spikelet are designated as being number 1,

Total grain weight and grain number of the head were 2.48 g

and 59 grains, respectively. '. . . . . . . . .. . .

65

66 cultivar grown under '3/24 irrigation treatment’

conditions at the Casa Grande Overpass Farm 1979-1980

growing season. The most basal spikelets and most basal

florest in a given spikelet are designated as being

number 1, Total grain weight and grain number of the head are 2.40 g and 52 grains, respectively. . . . ,- . 67

10. .Weight ..of individual grains from a head of high yielding cultivar grown under '3/11 irrigation treatment' at the

Casa Grande Overpass Farm, Tucson, during the 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number

1. Total grain weight and grain number of the head are

1.92 g, and 60 grains, respectively. ... 68

11. Weight of individual grains from a head Of low yielding

Grande Overpass Farm during the 1979-1980 growing season.

The most basal spikelets and most basal florets in a given

spikelet are designated as being number 1. Total grain

weight and grain number of the head are 1.88 g and 46 grains,

respectively. . , . . . . . . . . • . . . . 70

12. Weight of individual grains from a head of low yielding

cultivar grown, under ’3/24 irrigation treatment’ conditions

at the Casa Grande Overpass Farm during the 1979-1980

growing season. The most basal spikelets and most basal

florets in a given spikelet are designated as being number 1,

Total grain weight and grain number of the head were 1.20 g

and 34 grains, respectively. . . ' . . . . . , 71

13. Weight of individual grains from, a head of low yielding cultivar grown under ’well-watered' conditions at the

xi

LIST OF ILLUSTRATIONS— Continued

Figure Page

Casa Grande. Overpass Farm during the 1979-1980 growing

season. The most basal spikelets and most basal florets.

in a given spikelet are designated as being number 1.

Total grain weight and grain number of the head were

1.32 g and 44 grains, respectively. , . , 72

14. Soil and plant water potentials of entries grown under

’dryland' conditions at the Casa Grande Overpass Farm

during the 1979-1930 growng season. .

.

.

.

.

.

.

15. Soil and plant water potentials of entries grown under

’dryland' condition at the Casa Grande Overpass Farm during the 1979-1980 growing season. . . . . . .

. 8 9

88

16. Relationship of leaf water potential 01), osmotic potential, ( tt

) and turgor pressure (p) at specified

dates for Zaragoza plants grown under 'dryland' conditions

at the Casa Grande Overpass Farm during the 1979-1980

growing season. . . . . . ' . . . . . . 90

17• Relationship of leaf water potential O 1), osmotic potential (it) and turgor pressure (p) at specified

dates for Ramona plants grown under 'dryland' conditions

at the Casa Grande Overpass Farm during the 1979-1980 .

growing season. . . . . . . . . . . . . . . 91

18. Soil and plant water potential of different entries grown

using recommended irrigation levels at the Casa Grande

Overpass Farm during the 1979-1930 growing season. . . 93

19. Relationship of leaf water potential O'!), osmotic potential (v) and turgor pressure (p) at specified dates for Zaragoza grown under 1 well irrigated' conditions at the Casa Grande Farm during the 1979-1980 growing season. • 94

20. Relationship of leaf water potential (Yl), osmotic potential !>) and turgor pressure (p) at specified :

dates for Ramona plants grown under 'well irrigated'

conditions at the Casa Grande Overpass Farm during the

1979-1980 growing season. . . ■ . . . . 95

ABSTRACT

A nunber of conmeroial. and experimental lines of spring wheat

(Triticum asetivum L.) grown as 'dryland' winter crops in two desert

Idealities of Arizona were examined to determine if physiological or .

developmental traits could be correlated with yield. At Mesa, plants

were grown on a clay loam soil in 1973-1979, and also in 1979-1980. .

In Tucson, plants were grown on a sandy loam soil in 1979-1980. All

dryland treatments received 150 mm pre-plant irrigation. In Mesa, 150

mm of rainfall .occurred during the first season, and 153 cm occurred

in the second season. In Tucson, there was 134 mm rainfall during the

growing season. In addition to the dryland studies, plants were also

grown in Tucson on borders that received (a) 75 mm water 2 to 3 weeks

before flowering; (b) 75 cm water 1 week before flowering and (c)

recommended levels (525-mm) of water. ■

Yields in Mesa ranged from 2400 to 3400 kg/ha in 1979,:and

2400 to 3700 kg/ha in 1980. Under dryland conditions in Tucson, the.

yields ranged from 1100 to 3000 kg/ha. When watered 2 to 3 weeks

before flowering, yields ranged from 2300 to 3600 kg/ha; when

irrigated 1 week prior to anthesis, yields were 1600 to 3400 kg/ha;

and the well watered treatments yielded 2700 to 4500 kg/ha. The

rankings of the different lines according to yield was maintained

regardless of the site, growing season, or amount of irrigation.

When grown under dry land conditions, highly significant

correlations were found between yield and grain weight/1000 seeds

(correlation coefficients listed•in order:.\Mpsa 1978-1979; Mesa,:

x m

1979-1980; and Tucson, 1979-1980 were r=0.93, 0.96, 0.99); grain

weight/spike 0=0.93, 0.96, 0.97); Head weight/plant 0=0.93, 0.97,

0.96); LAI after anthesis 0=0.91, 0.98, 0.95); total dry weight/plant

0=0.98 , 0.95 , 0.93).

Similar correlations were also found.in trials which received

additional irrigation(s).. No significant correlation was found

between yield and tiller number/m2 except for the well watered

treatment (r=.85) indicating that regardless of the yield potential,

all cultivars tended to produce the same number of tillers/m2.

Usually, no significant relationship was found between yield and grain

number/spike or grains/m2, Correlation coefficients between yield

and LAI improved from nonsignificant at early vegetative stages to

suggesting the importance of photosynthesis during head development,

Wide differences in leaf water potential and leaf elongation,

rates were also found. Generally, high yielding cultivars had higher

leaf water potential than lower yielding ones under well watered and

dry land conditions in Tucson. Osmotic adjustment was observed in all

cultivars but to a lesser extent in low yielding cultivars. Total

length of leaves measured 1 to 2 weeks prior to anthesis were less

under dryland conditions than that of well watered treatments.

INTRODUCTION

Cereal grains are the major foods of mankind. In many Third

World countries cereals provide two thirds or more of the dietary

needs of the population (6). Rice (Orvza sativa L.), in Asia, sorghum

(Sorghum vuleare L.) in Africa, and wheat (Triticum asetivum L.) in

the Middle East are staple foods and their yields often determine

whether there is feast or famine.

A number of important physiological processes contribute to

grain formation in cereals. Among these are: photosynthesis

translocation of assimilates to the grain, cell division and cell,

enlargement, and uptake and transport of nutrients to the grain for

storage and cell metabolism. In order to obtain optimum yields, these

processes must function at high rates at appropriate stages of growth,

and environmental factors such as light, nutrients and water are known

to affect their activities. Water availability is often the -most

usually the major cause of yield reduction (28, 59).

Wide differences in yield and water use efficiencies obtained when cereal crops are grown under limited moisture

conditions, but most of the basis for these differences are still

unknown. In Mesa, Arizona, which is climatically similar to many

Mediterranean regions, yields ranging from 2600 to 3811 kg/ha were .

obtained in 1977-73 when different spring wheat cultivars were grown

using 5-acre-inch (150 kg/m?.) irrigation and about '200 kg/m?

rainfall (52). .These yields,;in turn, are 'considerably higher than

2

1800 kg/ha values obtained normally with winter wheats in areas such

as Manhattan, Kansas, which receives 850 kg/m2 annual rainfall (27).

Comparisons of this kind suggest there is a considerable potential for

growing spring wheats using limited water In certain desert regions,

but much more must be learned before the best cultivars can be

selected.

The major objective of this study was to gain an understanding about why spring wheat cultivars can differ so greatly in yield when they are grown in Arizona desert regions with limited water. It was felt that a clear knowledge of the effect of water stress on growth

,

and developmental patterns of the different cultivars will help

provide this understanding. Accordingly, yields of plants grown on

limited moisture in the field were studied in relation to vegetative and reproductive organ developement.

3

REVIEW OF LITERATURE

Effect of Water Stress on Physiological Processes -

The effects of water deficits on physiological processes have

been described in a number of recent articles (14, 24,, 51). Salter

and Goodie (49) have summarized much of the work done with crop plants

in the period from 1880 to 1967. More recently, Hsiao (29), Hsiao et

al. (30) and. Turner (53) have presented general reviews covering many

aspects of stress, and the effects of water deficiencies on specific

physiological, processes such as leaf enlargement (8), partitioning of

been analyzed.

All of the mentioned reviews have provided interesting and•

useful information but much of the coverage was not directed

specifically toward understanding how grain.yields of wheat and often

monocots might be altered by water stress. In this literature review,

particular emphasis will be placed on examining literature pertaining

to stress effects on grain production.

Growth Stages of Cereal Crops

The stages of growth and development of the majority of grain

crops are similar and can be described using the Feekes Scale (34).

In this review and study, this scale was used to identify specific

stages of development, but a more generalized description of various

growth stages is given below: :

4

Stage

Germination

Tillering

Jointing

Shooting

Booting

Heading and Earing

Flowering, or Anthesis

Grain Formation

Details

Appearance of the radicle.

Formation of tillers, i.e. branches

from the base of the stem.

Stage when 2 nodes can be Seen, /

i.e. beginning of shoot

elongation.

Elongation of internodes.

End of shooting stage and just

prior to emergence of ears.

Emergence of the ear from the tube

framed by the leaf sheath.

Opening of flowers and emergence of

anthers.

Period of grain development from

fertilization until maturity. This

period can be further sub-divided

into following stages:

'Milk Ripe1-grain contents have

'Soft Dough'-grain contents have a .

doughy consistency.

'Waxy Ripe'-grain contents have a

'Full Ripe'-Grain contents are

5 hard.

’Dead Ripe1-grain ripe for cutting.

Leaf Enlargement, Development and Senescence

Leaf enlargement in the most sensitive of the many plant .

(Helianthus annus L ,). soybean (Glycine max L.) and corn (Zea mays

L.), Boyer (8) showed that stress levels required to inhibit growth

were substantially less than required to decrease photosynthesis.

Nevertheless, much still remains unknown about stress effects on this

process and there is evidence that sensitivity of growth to water

deficits can vary widely. In corn seedlings, leaf enlargement .

declined rapidly at leaf water potentials (?) below -2 bars and ceased .

' ■ .

*

at ¥ of -7 to -9 bars (2). In field grown corn, however, Matts (57) found leaf extension was reduced only.slightly until ¥ fell to -8 bars.

has been shown to inhibit formation of new leaves through effects on .

leaf initiation and cell division (31), and it also hastens the rate

of senescence in many crops, including wheat (21, 39). These stress

induced reductions in leaf area are of great consequence since they

effectively reduce photosynthesis. In wheat, stress during early

growth may result in lower leaf area indicies due to reduced leaf

expansion or even leaf mumbers. Water deficiencies at later stages

may cause a rapid reduction In assimilate supply at the time of rapid : grain development. It has been shown that yield under dryland

conditions is related to the green photosynthetic area present at the' tame of anthesis (22, 39),

Water Stress and Photosynthesis

Much emphasis has been placed.on understanding stress effects

oh photosynthesis. During early stages of wheat growth,

photosynthesis is repaired for production of new leaves and stems, but

as plant ages, proportionately smaller amounts of assimilates are.

flowering, and post flowering growth primarily reflects head growth,

which occurs because of the partitioning of assimilate from existing

leaves to flowers and grains, or because of photosynthesis by awns and

other parts of the head (19)

Water stress effects on photosynthesis have been attributed to

both stomatal and nonstomatal factors (10), Water loss usually

effects stomatal closure which reduces water loss but also C0o

exchange. Many reports have shown close parallels between stress

induced decrease in photosynthesis and transpiration (10, 32, 33)•

Although the consensus is that reductions in photosynthesis

occur primarily because of stomate closure, stress induced inhibition

of chloroplast activity is also known to occur (45). Boyer (9) showed

leaf y at which stomata closed in maize (Zea mays, L.), In addition to

effects on stomata and chlorplasts, Neals and Incoll (41) reported

that water stress led to accumulation of assimilates in the leaf.

7

They speculated this accumulation somehow limits photosynthesis, but

their evidence for this was not conclusive.

Quantitative data relating water stress to photosynthetic

rates and grain yields are available for wheat and other grain crops

grown in controlled environment chambers. Johnson et al. (32) studied

the effect of water stress on spring wheat. When water was withheld .

from the soil for 7 days after spike emergence, flag leaf V fell from

-5 to -33 bars over the course of a week, and rates of photsynthesis

Net photosynthesis became insignificant at water potentials of -31 to

-33 bars, and flag leaf and spike transpiration rates approached zero at -23 to -31 bars, respectively.

to 11 days during the (a) boot stage (b) anthesis to milk-ripe

interval, and (c) both periods. Thein data showed that photosynthetic

rates were increased significantly when stress was applied during the

boot stage; however, grain yields were reduced 20%. Stress during the

anthesis to milk-ripe stage led to a.slight decrease in photosynthesis

but a 58% reduction in grain production. Photosynthetic rates and

grain yields were reduced 80 to 67%, respectively in treatments

receiving stress during both periods.

Boyer and McPherson (11) studied the effects of water stress

during grain filling on photosynthesis and yield of corn. They grew

plants under high .and low relative humidity (RH) conditions and

induced various degrees of'stress by reducing the amount of water

applied. Photosynthesis and grain yields were reduced 15 and 47%,

respectively in low RH pre-treated plants which received one seventh

of the amount of water as the.controls (which received water to field

capacity daily); in contrast, photosynthesis and grain yields were

reduced 35 and 68% in high RH pre-treated and stressed plants,

Stressed plants grown under low RH also had higher leaf ¥, lower

periods than those pre-treated with high RH. They reported that '14%

of the vegetative dry weight was lost to the developing grain when

plants were grown under low RH and stressed prior to grain filling.

In contrast, 8 % was lost by high RH pre-treated plants and 2 % by the

control plants. Additionally, low RH pre-treated plants formed grain

roughly in proportion to the total.dry matter that had been

accumulated during the growing•season and not according to

photosynthesis which occurred during the grain filling period, Based

on these data, Boyer and McPherson concluded that (a) nongrain

portions of the plants grown under low and high RH* and later ,

stressed, mobilized their reserves to the developing ear to compensate

for the reduction in transport of assimilates from the leaves, (b)

there are assimilates stored in shoots which are available for grain

growth, but these may never reach the head when moisture is adequate.

Translocation

.

' ' .

-

Carbohydrates used in grain filling must be moved from leaves or other photosynthetic areas (sources) to the developing grain this transfer. Potentially, stress can reduce translocation by

9 lowering photosynthesis and thereby decreasing assimilate supply,

increasing assimilate utilization by source or decreasing substrate

usage by sink leaves, reducing loading or unloading of sieve elements,

or affecting the velocity of assimilate transport in the sieve type

elements. '

Wardlaw (54, 55) reported that the velocity of assimilate -

movement in the sieve elements was unaffected when leaf blade T

dropped to -30 bars in wheat at grain filling, or in darnell (Lolium

temulentum L.) during vegetative growth; however, stress reduced

overall translocation in both crops. In the vegetatively growing

darnell, leaf expansion was more sensitive to stress than

photosynthesis, which suggests stress effects on sink formation may be

critical in regulating translocation. On the other hand, grain

development of wheat was less sensitive to stress than GO

d

affecting translocation. Wardlaw (56) attempted stress reduced translocation in wheat by lowering photosynthesis or directly affecting the translocation mechanism. He manipulated the amount of photsynthetic tissue (source) relative to the utilizing

' tissue (sink) in wheat. When the amount of sink stressed plants the same as in the controls, although the total quantity of 14c'

transported was less than in the controls. Wardlaw interpreted these

results to indicate that translocation mechanism itself was not

affected by stress, and the effect of stress on photsynthetic activity

10

corn, on the other hand, stress during grain filling reduced

translocation, Brevedon and Bodges (12) exposed source leaves of

well-watered (¥1= -26 bars) corn to labeled CO^ and found that the

incorporated C14 was retained for 2 hours in the control and 5 hours

in Stressed plants. Based on these data, they speculated that stress

may affect the phloem loading process.

In reality, it is difficult to study translocation in plants,

and we must conclude that stress effects on this process are only

poorly understood.

New Formed Assimilates

Grain production in wheat depends on the transfer of

assimilates from source leaves and awns to the developing grain, The

principles that govern partitioning of assimilates amoung organs of a

plant are not fully understood (58), but some data showing change in

distribution of carbohydrates during normal plant development are

available. Ra'wson and Bofstra (47) labeled selected wheat leaves with

l^co at various stages of plant development. Prior to anthesis,

they found that the second youngest fully-emergent leaf was the major

exporter of labeled assimilates and this leaf was the principal

supplier of substrate to young leaves and the shoot apex. Older

tillers. After anthesis, however, the head rapidly became the

dominant sink for assimilates produced in young leaves while the lower

leaves-continued to supply the roots and tillers, and most.of the

assimilates exported by the flag leaf and leaves were directed to the

11

developing head, Because of results of this type, Marshall and

Wardlaw (35) stated that a large potential sink for assimilates will

determine the pattern of distribution.

Assimilate distribution is altered considerably by

environmental conditions. Drought and low temperature tend to favor

root growth relative to shoot growth (35), but the pattern of

assimilate distribution is not.clear.in stressed plants. This is

largely due to the differential influence of water deficiencies of

leaf enlargement, photosynthesis, phloem loading and unloading, and :

grain filling. Additionally the duration, severity and timing of

stress in different organs will change the distribution pattern of

assimilates. Wardlaw (55) showed that in darhell, water stress during

vegetative growth caused preferential movement of labeled assimilates

to young leaves, sheaths and roots. In wheat, stress during grain

filling reduced leaf assimilation of C02 and so resulted in moving

recently synthesized assimilates from the lower leaves, stems, roots

and crown to the ears. Brevedon and Hodges (12) showed that in corn,

.

2

from the flag leaf to the cob and kernels.

Mobilization and Distribution of Stored reserves

Grain yields are determined partly and in some cases nearly

totally by photosynthesis occurring after anthesis; however,

assimilates produced earlier and incorporated within leaf, stems, and

roots can contribute significantly to grain yield. The fraction of

grain which is derived from these reserves depends on the type of

12

crop and on the prevailing environmental conditions. Under well

watered, conditions, Rawson and Evans (48) showed that contribution of

pre-anthesis assimilates is about

30% of final grain weight in barley

(Hordeum vulsare L.) but only 3 to 10% in wheat. Gallagher and Biscoe

(

23) showed that up to 70% of the final yield of barley was due to

material translocated from the stem. Similarly, Wardlaw (56) reported

that under stress wheat translocated reserved photosynthates from

stems and lower leaves to the grain. Passioura (42) reported that

about two thirds of the final grain weight came from redistribution of

assimilates after anthesis in severly stressed wheat plants grown

under dryland conditions in the field.

Evans and Wardlaw (18) noted similar changes in. assimilate

distribution in many other crops and they concluded that carbohydrate

reserves make a major contribution to grain yield in most cereal crops

under stress conditions, but when nutrition and water supply are

favorable, the reserves are mobilized only to a limited extent. They

state ”Although stored reserves are of value in adaptation and as

insurance against late stresses they nevertheless, represent unused ■ yield potential."

Effect of Water Stress at Different Stages of Development on Grain

Yield ,

The effect of water deficit at various stages of development

on crop growth yield have been studied■emperically by a number of

workers (4, 5, 49)> Generally, plants were stressed during.the

13 following 5 stages: planting to emergence, emergence to jointing, .

jointing to heading, heading to soft ripe, and soft ripe to maturity,

Milthrope (37) studied the effect of water stress, on wheat

seeds and seedlings grown on peat moss in controlled environment

were, three periods in which desiccation resistance varied considerably

when he withheld water for 4 days. The first stage covered the time

from beginning of soaking until the coleptile was about 3 to 4 mm long. During this period the seedlings were completely resistant to

' -

drought as was shown by the fact that serverely dried plants resumed

elongation on rewatering at a rate comparable with that of well

watered plants. The second stage covered the period from elongation

of coleptile to the emergence of the first leaf . During this period

plants were not permanently injured by a loss of 98% of total

moisture, although elongating roots were killed. The third stage

studied in these experiments covered the period from emergence of the

first leaf until emergence of the second leaf; during this time far

less water (

20%) had to be lost before expanded tissue was killed, and :

the growth rate was permanently reduced by a 10% loss of water. In a

needed for emergence of 97 lines of wheat almost doubled for each .

decrease of soil water potential (ws) of 4 bars. There were

signifleant differences■in emergence characteristics of various lines,

which suggested that drought resistant lines' can be selected for in

areas where water supply is inadequate.

14

Bnergenee to Jointing

The effect of water stress at this stage of growth is crucial,

since spikelet and tiller numbers can be reduced (1). Milthrope (33)

stressed wheat plants growing in peat moss in growth chamber by-

withholding water for

1 week at the time of rapid leaf development and

also time of spike initiation. Drought during rapid leaf development

reduced number of fertile tillers, and water deficits during spikelet

initiation reduced their number.

Day and Tntalap (15) found that water stress at jointing

resulted in a 50% reduction in yield- which was due mainly to reduction

in number of ears/hectare as well as fewer number of seeds per ear.

In contrast, Abdel Sarnie and Talha (1) reported that yield was 10%

more than well watered controls when, water stress was imposed after

the active tillering stage.

Jointing to ffeading

For many years attempts were made to identify the so called

1 critical period' when water stress effects are most severe. Although

water deficit at almost all stages of ontogeny lower yields of wheat,

there is considerable evidence that yield loss is greatest when plants

(13, 15). Fischer (20) applied a series of single stress treatments

(-2 bars/day) for a total of 4 days to wheat at various stages of

growth. He found the most sensitive state was about 3 weeks on either

side of anthesis. He noted- that this period corresponded to the time

of rapid elongation of ears, anthers, and carpels, and the ocurrence .

15

of meiosis in pollen mother cells. Plants stressed at this stage had

abnormal anthers but normal female parts and grain yield was reduced

significantly because of reduction in number of grains and grain

weight per ear. Day and Thompson (16) reported that in barley, grain

bushel weights as well" as grain number .per ear .were reduced when

stress occurred at flowering and yields were decreased about

20$ i

Heading to Soft Ripe

Sensitivity to. drought drops considerably after anthesis (20).

Gull, and Allan (25). found that water stress applied by withholding

water during the first 14 days after anthesis did not affect wheat

grain yield even though leaf area was reduced and leaf senescence was

hastened; however, yields were reduced when stress occurred

27 and 34

days after anthesis when leaves and stems normally yellow. They ,

concluded that reduction in yield was due to■depression of assimilate

translocation to the ear. In a field study, Day and Tntalap (15)

reported that wheat yields dropped less when plants.were stressd at

the dough stage than at jointing or flowering stages. Fischer (20)

reported that grain yields were not affected if stress was applied

3

Soft Ripe to Maturity

Few experiments have been conducted during this stage of

growth and most of them indicate that stress at this time has little

effect on yield (25, 15,;38), Abdel-Sarnie and Talha (1) reported that

water stress at maturation or ripening increased yield as much as 40%.

16 of the control during maturation and

90%

during ripening. Milthrope

(38) and Hsiao et al. (30) however, stated that stress during grain

formation and maturity will reduce grain weight per head due to

hastened senescence and reduced assimilated translocation to the

grain.

17

SUMMARY OF PERTINENT LITERATURE

The available literature has shewn that water stress can

reduce yield of all grains such as wheat in various ways.. Stress

during early stages of growth can reduce leaf area by inhibiting

enlargement and also leaf initiation thus effectively reduces assimilate supply. Additionally, viable head producing tillers and

' / •

spikelet numbers can be altered by stress during early plant growth.

Water deficits at later stages of growth can reduce yields by

hastening senescence which results in reduced photosynthesis during

effects of stress on physiological functions such as photosynthesis

and grain development mechanisms.

Examples have been cited which show that growth and responses

of plants at any stage depends on treatments which occurred previously

and this should not be ignored in studies of stress effects on yield.

As an example, low relative humidity encountered during early growth

may contribute to hardiness of plants grown in desert regions.

It has also been shown that resistance to stress varies widely

with the growth stage of a plant and workers such as Fischer (20) .

suggest that major reduction in yield will.occur when water deficits

are encountered 2 to 3 weeks prior to anthesis. This idea seems

applicable to wheat grown in Arizona since much of the early

development occurs under conditions of high soil water availability

and cool temperatures— which tend to reduce transpiration and soil

moisture- depletion. Stress at other stages may also be of great

importance, and plant responses occuring during these periods of

18

growth will also be recognized so the further knowledge required for

irrigation management can be obtained.

19

MATERIALS AND METHODS

Identification of seed sources

A broad spectrum of spring wheat lines selected for lodging

resistance, high yield, and early maturity under southwestern

conditions were used in this study (Tables 1 and 2). In addition to

experimental lines, four commercial varieties: Aim, Cajeme 71, Siete

Cerros, and Zaragoza which are commonly planted In irrigated desert

regions in Arizona were also used (17). All germplasms will be

referred to as entries in the following text.

Experimental entries were developed by R. Thompson at the

University of Arizona Mesa Experimental Station through a male sterile

yielding bread wheat. The program consists of developing pools of

male sterile, and male fertile lines selected from populations

segregating for reduced height and male sterility. Using sterile

females, crosses were completed between desired plants. The F|

generation was collected in bulk and selected crosses of short

statured, male fertile plants were next bulked (46). The experimental

entries were populations established by recurrent selections using

phenotypic criteria such as height, seed size, tillering, maturity,

and date of anthesis.

Field Design

Experiments were conducted at the University of Arizona Mesa

Experiment Station, Mesa, Arizona and at the Casa Grande Overpass

TABLE 1. Entries and source used at Mesa during the 1978-1979, and 1979-1980 growing seasons

Entry

1978-1979

Seed Source

Entry

1 9 79-1980

Seed Source

1 Cajeme 71

2 Siete Cerros

3 AIM

4 PICT1C 62

5 GABO

6 ARVANO

7 Florence Aurore

8 MSF R S Early Pop

9 M S F R S Base Pop

10 MSF R S Large Seed

11 M S F R S Large Seed Cross

12 MSF R S Bulk Seed

13 MSF R S Se l f - P l a n t i n g Bulk

ACIA*

A C 1 A

ACIA

C1YMMT

CIYMMT

CIYMMT

CIYMM1

Rex T hompson

Rex Thompson

Rex Thompson

Rex Thompson

Rex Thompson

Rex Thompson

1 Cajeme 71

2 Siete Cerros

3 AIM

4 PICTIC 62

5 G A B O

6 Toluca

7 Anza ft Mex i p a k

9 M S I R S Ear l y Pop

10 M S F R S Base Pop

11 M S F R S Large Seed

12 M S F R S Bulk Seed

13 M S F R S Sel f - P l a n t i n g Bulk

ACIA

AC I A

ACIA

CIYMMT

CIYMMT

CIYMM1

CIYM4I

CIYMMT

Rex Thompson

Rex T hompson

Rex Thompson

Rex Thompson

Rex Thompson

A preplant Irrigation of 150 k g / m ^ w a s applied one week before each plan t i n g and 100 kg^/ha and 90 kg P^O^/ha were a pplied duri n g seed bed preparat

Entries were planted on D e cember 6, and N ovember 29 in 1978 and 1979, respect i v e l y , and were h arvested on May 20, 1979 and Ma y 5, 1980.

‘Arizona Crop Improvement A s s o c i a t i o n

TABLE 2. Listing of entries, seed sources of wheat, and time of irrigation for Experiment III conducted at the Casa Grande Overpass F a r m , Tucson, during the 1979-1980 growing season

1979- 1 9 8 0

Ir r i g a t i o n T r e a t m e n t s

E ntry Seed Sour c e

1 Ramona

2 A R V A N D

3 A IM

4 F l o r e n c e A u r o r e

5 Siete Cerr o s

6 C a j e m e 71

AC I A*

C I Y M M T

A C 1 A

CIYMMT

A C I A

AC IA

1 D r y l a n d - P r e pla n t o n l y (150 k g / m )

2 3/11 T r e a t m e n t - P r e pla n t irrig a t i o n and 75 kg/ m ^ w a t e r on 3/11

3 3/24 T r e a t m e n t - P r e p l a n t i r r i g a t i o n and 75 kg/ n / w a t e r on 3/24

4 Well w a t e r e d ( c o n t r o l ) P r e - p a i n t and 3/6 , 3/16, 3/26, 4/10, 4/24

(75 kg/ m ^ e a c h time)

7

Zaragoza

A 1 C A

TT

All e n t r i e s r e c e i v e d 6 0 kg /ha and 50 kg P ^O^/ha d u r i n g seedbed p r e p a r a t i o n s and 150 k g / m w a t e r o n e w e e k b e f o r e planting.

Entr i e s w e r e p l a n t e d at a r a t e of 15 kg/ha on D e c e m b e r 18, 1979 an d w e r e h a r v e s t e d on M a y 20, 1980.

*A r i z o n a C r o p Impro v e m e n t A s s o c i a t i o n

Farm, Tucson, Arizona, The'soil at the Mesa Farm is Avondale clay

Haulstoll (44). The soil at the Overpass Farm is a coarse loamy

member of Gila series, a typic Torriflurentic alluvial deposit.

Moisture released curves were obtained for the soil at the

Casa Grande Overpass Farm (Fig. 1) and ¥s were estimated using a

gravimetric soil sampling technique.

¥3 were also determined in

Experiment III using Merrill #74-13 screen cage psychrometers (Merrill

Instruments, Logan, Utah) placed 1 meter below the soil surface,

The experiments at Mesa, Arizona were cooperative studies

performed with R. Thompson and were conducted in the 1978-1979 and

1979-1980 growing seasons, Each plot contained six rows that were 5 m

in length and spaced

30 cm apart, and a 1,2 m alley separated all

plots from each other. The four center rows of each plot were used

for yield determination and'a

60 cm section in one row was staked out

for stand counts, in-situ observation of growth, and. final

harvest for

determination of head and straw characteristics. Throughout the

growing season, plants were harvested from the two outer guard rows

for observation of various developmental characteristics.

The experiments at Tucson were conducted in the 1979-1930

.length and spaced-45 cm apart, and an

0.9 m alley separated all plots

from each other. The two center rows of each plot were Used for yield

determination and a

60 cm section in these rows were staked out for

stand counts, in-situ observation of growth and final harvest for

determination of head and straw characteristics. Throughout the

LO

4

OQ

10.

% SOIL MOISTURE

20

FIG. 1

The m o is t u r e release c u r v e for the soil

at the Casa Grande O v er p as s Farm.

2 3

growing season, plants were harvested from the two outer guard rows

for various.developmental characteristics.

Experiment I .

Dry Land Wheat Yield Test (Mesa, 1978-1979).

Thirteen entries were planted in a randomized complete block

design with four replications per entry. Nitrogen (100 kg N as

*®4N0g/ha) and Phosphorous (90 kg PgOc/ha) were added prior to

seedbed preparation. A. preplant irrigation of 150 kg/m2

(6

Acre-inch) was added 1"week before planting. Seeds were planted on

December

6 , 1978 at a planting rate of 15 kg/ha, Arrangement of

entries within each replication was divided into three ranges to south orientation with a 3.05 m buffer zone of. wheat at either end.

The plants received no water except the preplant irrigation and seasonal rainfall (Table 3). The objective of this experiment was to.

determine physiological and morphological factors which are associated with high yield under 'dryland' conditions. .

Experiment II

Dry Land Wheat Yield Test (Mesa, 1979-1980)

This experiment was a follow-up of the previous experiment.

Thirteen entries (Table 3) were planted on Nbvanber 29, 1979 at the

Mesa. Experiment Station, Ten out of 13 entries were selected from

for Experiment I in a different season and the other six pre-presented

24

25

a new trial. The.'design and methods used were similar to those of

Experiment I except that in this experiment, four ranges of six row

plots each made up one replication. The seasonal rainfall is given in

Experiment III

Dry Land Wheat Yield Trial and Determination of Critical Irrigation

Period (Tucson, 1979-1980)

Seven entries consisting of high and low yielding varieties

selected using findings of Experiment I were chosen. Nitrogen (60

kg/ha) was added prior to seedbed preparation. An International

Harvester IH-295 planter.with.cones was employed for planting on

December 18, 1979.

The entries.were planted in a randomized complete block design

within each of four areas (borders) containing.six replications of

orientation with a buffer zone of barley at either end. Arrangement

of seven entries within each replication was divided into two ranges

consisting of four row plots per range with one entry repeated twice.

Seventy-five seeds (15 kg/ha) were planted to a (3 m) row, and the .

resulting population was 2.16 x 1.05 plants, per hectare. The borders

differed in irrigation treatment (Table 2). All borders received a

preplant irrgation of 150 kg/m2 (5 Acre-inch) 1 week before

(.irrigated wheat in Arizona (52). The dry land treatment received no

.26

TA BL E 3. M o n t h l y prec i p i tat i o n at M e sa ' a n d at the Casa Grande

Overpass Experiment Station during the 1 9 78-1979 and

Month

:

1 9 7 9 -1 9 8 0 growing seasons

' ' : ' "" !

p

A m ount of Rainfall kg/m

Mesa

1979 - 1 9 80

'

Tucson

1979-1980

November

Dece m b e r

January

February

March

/ 1 978-1979

15.50

68.00

64.75

2.25

.25

0

1.25

53.75

68.25

2 6.00

0

28.00

70.50

33.75

April

May

>

0

4.25

0

1.25

0

Seasonal rainfall was m e asured from time o f p l an t i ng at each location

to time of harvest.

27

water except the preplant irrigation and seasonal rainfall (Table 2),

Two other treatments received one irrigation of 75 kg/m2

(3

Acre-inch) in addition to the preplant irrigation; one treatment

received water

3 weeks, and the other 1 week before the estimated time

of anthesis. Anthesis was estimated using the.Feekes Scale (34) to

identify the growth stage of the plants and growth rates based on

results from Experiment I. The objectives of this study were (a) to .

determine how cultivars differ in yield under limited moisture

conditions (b) to locate the critical period for irrigation and (c) to

determine.the effect of irrigation on development and morphological

characteristics associated with high yielding ability.

Sampling for Developmental and Morphological Studies

After emergence, frequent checks were made on all entries.

Four plants were harvested randomly from the guard rows. .The plants

were placed in plastic bags and held at 4 to 3C prior to analysis.

In the laboratory, plants were washed and the number of

determined, The green leaves were then removed from the stem and leaf

area of two plants were measured using an Hayashi-Denko Model AM5

automatic leaf area meter. The leaves and the rest of the plant were

then oven dried at 60-70G and dry weights were recorded, The number of yellow leaves were counted to determine the rate of senescence

expressed as percentage of number of green leaves at time of anthesis.

This information was used to determine correlation of water stress and

the rate of senescence in different cultivars.

the date of anthesis with respect to border and replication. The date

of anthesis was the time when 50% of all heads in a given entry were

in bloom.

Handling of Harvest Data

A sampling unit of 2,23 m2 was established for all

replications and stand counts were made

3 weeks after emergence.

Tiller numbers were determined by subtracting the number of plants■ present in a given area

3 weeks after emergence from the total number

of shoots including small tillers at the time of the harvest. Each

sampling unit was hand harvested on May 20, 1979 and May 5, 1980

respectively for Experiments I and II at the Mesa Farm and May 20,

1980 for Experiment III at the Tucson Overpass Farm, After threshing,

grain weight

/ 1000 seed, grain weight, and total number of grains were

determined. An additional sample consisting of eight heads/plot were

used to determine number of grains/head, weight of grain/head,

.spikelet number/head, straw weight/head, and the weight of individual

grains. These data were used to correlate grain weight/head, and "

versus weight of individual grains were drawn to gain an idea about

the number of grains per spikelet and the contribution of each

spikelet to final head weight and yield. The heads selection for

these studies were those whose grain number and weights were similar,

to the means obtained for each entry, The remaining components of

yield such as number of grains/m

2 , ..-nunber of tillers/m2 , straw

28

29

weights/m^., and weight/head were calculated using the available

data,

•i

Nfeasurement of Plant Water Status and Growth

Four leaf discs were taken from the lower portion of the

youngest leaf blade and placed in the.chamber psychrometer, which was

transferred rapidly to an insulated box and carried to the laboratory, for the determination of

V

with a Keithley Wescor MJ-55 Microvoltmeter

(Wescor, Inc., Logan, Utah) after 2 to 3 hours of equilibration, Leaf

osmotic potentials were also determined by placing two leaf discs into

envelopes of aluminum foil and freezing the discs in liquid nitrogen.

The frozen samples were then held at -ISC untily determination was

made.

The elongation of rapidly expanding leaves was measured also

in Experiment III on a weekly basis to determine if leaf elongation

rates can be used to estimate water stress.

30

RESULTS AND DISCUSSIONS

Growth and Yield of Wheat under Limited Moisture Conditions

■Mesa, Arizona, 1978-1979

Comparison of Yield and Yield Components

Analysis of data from the 1973-1979 growing season have

confirmed previous observations (52) that good yields of wheat can be

obtained in Mesa, Arizona when plants are provided with only a

preplant irrigation of 150 kg/m2

(6 Acre-inch) and about 150kg/m2

of rainfall. Additionally, the results showed yields can vary

considerably depending on the genetic background of the plants (Table

4). The amounts of water used by the crops were significally less

than the 525 kg/m2 (21 Acre-inch) normally recommended for irrigated

fields in the Phoenix, Arizona area, and 800-850 kg/m2

(32 to 34

Acre-inch) which normally falls in Manhattan, Kansas. Yields obtained

in the best of the dryland entries (Siete Cerros 3400 kg/ha) are less

than the average obtained in Arizona (5000 kg/ha) under irrigated

conditions; but production by even the lowest yielding line (MSFRS,

Large Seed Cross, 2400 kg/ha).is comparable or superior to the

production values usually obtained in Manhattan, Kansas (2000 kg/ha,

K, Matsuda, Personal Communication).

Unquestionably, irrigation can normally increase production in

Arizona, but yields of some of the lines grown under ’dryland’

conditions are respectable and an understanding of the basis for yield

differences Obtained among the various entries may aid in selection of

plant types which will produce even greater amounts than.the 3400

TABLE 4. Yield and yield components o f commercial and experimental wheat entries from Mesa, 1978-1979

Entry

Bloom i n g Date Yield kg/ha

Wt(gr a m s ) /

1000 seed

Ktill e r s / m

#spikelets/ spike

# g rains/m

2

Igrains/ spike

Wt(grams)/ spike

Siete Cerros

M S F R S S e l . PI. Bulk

AIM

4/1

3/30

3/28

3/25 Cajeme 71

M S F R S Large Seed

M S F R S Early

GABO

P1CTIC 62

ARV A N O

M S F R S Base

MSF R S Bulk Seed

Florence Aurore

3/30

3/25

3/26

3/26

3/30

3/30

3/29

3/29

M S F R S Large Seed Cross 3/29

3378 A*

3183 A

3132 B

3028 BC

297 5 BC

2968 BCDE

2906 BCOEF

278 9 CDEF

2654 DEF

2592 EF

2593 EF

25 7 0 F

2423 F

46 . 8 A

44.4 AB

40.4 ABC

40.4 ABC

39.7 ABC

39.4 A B C D

38.9 ABC D

38.6 BCD

38.3 BCD

34.4 CD

37.3 CD

33.05 D

33.14 D

73 A

72 A

78 A

72 A

71 A

79 A

82 A

72 A

81 A

78 A

70 A

85 A

84 A

19.8 A

21.8 A

22.1 A

21 . 0 A

21.4 A

19.8 A

20.3 A

20. 0 A

21.3 A

22.6 A

20.8 A

18.9 A

19.8 A

7218 B

7180 BC

7752 A

7495 AB

7493 AB

7533 AB

7470 AB

7225 B

6929 C

7534 AB

6951 C

7776 A

7311 AB

50. 3 A

42.3 AB

4 4 . 3 AB

33.5 0

4 1 . 3 AB

35.8 BCD

32.3 D

44. 3 AB

40. 0 ABC

38.3 BC

42. 5 AB

28 . 0 D

45. 5 AB

2.583 A

2.400 AB

2.245 ABC

2.220 ABC

2.208 ABC

2.183 ABC

2.163 ABC

1.953 ABC

1.893 BC

1.733 C

1.720 C

1.680 C

1.628 C

* Values followed by the same letter w i t h i n one c o l u m n are not si g n i f i c a n t l y d i f f e r e n t at 5% level a c c o r d i n g to the Student Nen n a n Kuel test.

04

32

kg/ha obtained with Siete Germs. In order to gain a better

understanding of the basis for differences in performance, yields of

the different entries were listed in decreasing order and compared

with various yield components (Table 4). No conspicuous relation was

found between yield and blooming date; and also all entries had about

the same number of tillers and spikelets/spike. These measures

therefore were not considered factors which regulated yield

differences. Only a weak correlation was found between grain

numbers/unit area and yield (r=.34), but a somewhat better relation

was found between grain numbers/spike and yield (r=.65 Table 5). Much

higher correlations were found between yield and grain weight/spike

(r=.93) and grain weight/1000 seed (r=.93) • This suggested that

factors which contribute to grain weight and not tiller number were of primary concern in trying to understand why entries differed in yield

.

.

' " ‘ .

performance.

In order to clarify the relation of grain to head development,

the weights of individual grains on each spikelet were plotted as a

function of spikelet number with the basal part of spikelet designated

as being number

1 (Fig. 2-3). Such determinations were made for each

of 4 heads selected from each of the 4 replicates and comparisons were

made using heads with: total grain weights close to the mean obtained

for each entry. These comparisons showed (a) high yielding cultivars

tended to produce 4 to 5 grains per spikelet (Fig. 2) and (b) the

grains in the central region of these spikes tended to be larger than

those from corresponding.regions of heads from low yielding cultivars

(Fig. 3) which produced

3 grains per spikelet.

TABLE 5. Correlation coefficients for yield and morophological characters measured at different harvesting dates

"T...u

i < l

1 U

/ I

1 U

1 M

* 1 «

1 /

/ I

It IDw

IQ MM/ ptftM 4/11

I I w y /F ls » l 4 / I t

II H M e

11 6r«U4/eU

14 # «rtUk/»|»U«

15

i

l l l l e r s

It 4 »plk«l*U/¥>We

I U W e Uw 4 w 4

* I t "

I W

I I

4/1

li II A I

> % l 4 S 4 f e S W M

“ ■ « M l W " 1 II1il" I

*

.y

I * * » l i n

M•

* II il" I

* " 1

.

n * 1

i t i t I " II1 i t i t II1 *

i i i* i t

l. it II1 1

i t l*

i t il" I " i t i t I

I " I

M it H

i t 4

• " « 1 •

* li1

ll" i t II1tl*

* 1 i.l

II1I *

I " * m

M t I t w t .

i t .

• * I 1

I * it" • I * * * 4 * I " I t ii" 1

»".t

II1t 1 l

" • 1W

I * • it II1 il" I " I W / i t ll1 I 1 .

4

1

II1

1 it 1 it i i i t i t i.l.

II1 It. i 1 4 i.l. II1

I * 1 1 I * * i

* it u I tl1

" • * 1 il" ii" .

4 1 I * t I t .

.

I t il1ti1

.

1 t I

1

" 1 .il1

I * l/ I I W t ll" • " it* t I * * t 4

.

1 i t .

1 t il1

I i t

1 I t

1 I * t .

1

.

4

U.S. .»l" ».». ».i. H * .»•" . U * * 1 . II* II* iil i t. e.S. e.l. i S. i.l. i t. m t i t

I.l. I.l. U * .14

It. to*

U l

1 1. I t l i l t I t 11.

4 1 I.t. It. 1 t. • 1 I t

I41 ll1 1 1 44* .ti" li‘ I.t. 441

441

I t il"

44*

S. W »»U«4 4re s li# * II U * * 4 « l OS 4*1 0 . 1 e*4 /u r le ts r e i ^ e i ll t r e lf

O S. fcel S l« » 4 « lim e l # OS le v e l

AtArwe le i lews; I A | . le e / Aree l* le a ( le e / eree/yrew W e ie e ). IUW. le ie l IW y , UW. IN y

' O

2 s

3 o

4 *

#

SIETE CERROS

to 15 20

SPIKLET NUMBER

FIG. 2 Weight of individual grains from a head of a high yielding cultivar grown under 'dryland1 conditions in Mesa during the 1978-1979 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain numbers of the head were 2.81 g, and 50 grains, respectively.

I t

2

3 O

MSFRS LARGE SEED CROSS LINE

* * #

* *

° o

5 10 10 20

SPIKLET NUMBER

FIG. 3 Weight of individual grains from a head of a low yielding

1978-1979 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1.

Total grain weight and grain numbers of the head were 1.63 g, and

46 grains, respectively.

36

/Crop Growth Analysis

Grain development depends on assimilates provided by organs

such as leaves and stems. In order to understand better how

vegetative growth may affect grain yields, plants were harvested at

various intervals, and comparisons made of the (a) above ground total

dry weights (Table 6), (b) heads and shoot dry weights (Table 7), (c)

leaf area indices (Table 8), (d) and the.relative area of green leaves

following anthesis (Table 9). In all of the above tables, the entries

were listed in order of decreasing yield (Table 4), and correlation

coefficients obtained in comparisons with yield and other measures are

given in Table 5.

The above ground weights of all entries increased continuously

from the first (Feb. 1) through the final (April 25) sampling period:

(Table 6), Differences were found in dry weights among entries, and

from anthesis (April 2) onward, dry weights and yield differences

closely paralleled each other (Table 5)» Usually Siete Cerros, the

highest yielding entry, had the highest dry.weights of all sampling

dates (Table 6), but the ability to grow well vegetatively is

apparently not a general indicator of yield potential. This is

suggested partly because dry weights of entries sampled'during

vegetative growth in February, and early March, were not highly '

(Table 7) were not related to yield (Table 5). These results are

consistent with findings of Fisher and Boyer and McPherson,(11),

In contrast to the straw weight data, head weight differences

from anthesis onward were correlated closely to yield differences

TABLE 6. Total above ground dry weights of commercial and experimental lines of wheat at different dates in Mesa, 1978-1979 growing season

Entry TOW 2/1 TOW 2/12

TOW 2/22 TOW 3/5 TOW 3/22 TOW 4/2

TOW 4/13 TOW 4/25

Siete Cerros

.366 A * 1

M S F R S Self planting bulk .1 9 3 e

AIM .182 B

Cajeme 71

MSF R S Large Seed

MSF R S Early

GABO

PICTIC 62

ARVANO

MSFRS Base

MSF R S Bulk Seed

Florence Aurore

MSF R S Large Seed Cross

.201 B

.216 B

.243 B

.222 B

.178 B

.218 B

.196 B

.304 AB

.167 C

.163 C

.733 A

.721 ABC

.560 ABC D

.694 ABC

.596 ABC D

.475

0

.607 ABC O

.575 ABC O

.581 ABC O

.509 BCD

.531 AB C D

.591 A B C O

.545 ABC D

1.95 A

1.79 AB

1.90 AB

2.24 A

1.44 CO

1.74 BC

1.52 C

1.54 C

1.74 BC

1.40 0

1.44 CD

1.53 C

1.40 CD

3.27 A

2.91 A

2.77 AB

2.58 AB

2.53 AB

2.23 C

2.82 A

2.77 AB

2.48 BC

1.99 0

2.79 AB

2.42 C

2.78 0

6.2 3 A

5.76 B

4.73 C

4. 9 0 C

5.15 B

5.36 B

5.34 0

5.21 B

4.81 C

4. 7 0 C

4.63 C

4 .64 C

2.8 3 C

8. 0 5 A

7.00 A

6.41 AB

6.82 AB

6. 2 0 C

6.04 C

5.74 CO

6.25 C

5.87 CD

5.38 0

6. 1 0 C

5.17 E

6 . 1 0 E

9.28 A

8.95 A

7.48 AB

7.04 AB

7.61 AB

7.72 AB

6.94 B

7.25 B

6.63 BC

6.37 C

6.23 C

6.1 0 C

6.65 BC

11.57 A

10.00 B

9.87 B

9.6 0 B

8.8 3 BC

8.7 8 BC

8. 3 8 C

7.90 CD

7.68 D

7.62 D

7.72 0

7.56 0

7.30 E

* Values followed by the same letter w i t h i n a c o l u m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0.0 5 level a c c o r d i n g to the Student Newman Kuel test

^ Dry weights e x pressed in gram/plant.

TABLE 7. Dry weights of heads and straw of commercial and experimental lines of wheat at specified dates in Mesa, 1978-1979 season

G r a m dr y w e i g h t s at d e s i g n a t e d sampling dates

Entry

Siete Cerros

M S F R S Self P lanting Bulk

A I M

C a j e m e 71

M S F R S Large Seed

M S F R S Early

GA B O

PICTIC 62

A R V A N O

M S F R S Base

M S F R S Bulk Seed

Flor e n c e Aurore

M S F R S Large Seed Cross

Head/ P l a n t

April 2

Straw / P l a n t

1.33

A*1

1.31

A

1.30

A

1.25

B

1.23

B

1.21

B

1.20

C

1.15

0

1.13

0

1.07

0

1.08

0

1.07

E

1.01

E

6.71 A

5. 6 9 B

5.1 0 C

5.56 B

4.97 BC

4.83 BC

4.6 9 CO

5.0 9 BC

4.7 3 CO

4.31 0

5.01 BC

4 . 1 0 0

5. 0 9 BC

H e ad/Plant

2.81 A

2.5 0 B

2.49 AB

2.36 A0

2.32 AO

2.13 BC

2.01 C

1.99 C

1 .95 C

1.68 0

1.76 CD

1.62 0

1.55 0

April 13

Straw / P l a n t

6.47 A

6.35 A

4.99 B

4.68 C

5.2 9 B

5.5 9 AB

4.9 3 BC

5.26 B

4.68 C

4.6 9 C

4.47 0

4.4 8 0

6. 1 0 B

H e a d / P l a n t

5.13 A

4.84 A

4.75 AB

4.61 AB

4.17 B

4.0 0 B

3.69 C

3.55 C

3.53 C

3.36 0

3.47 CD

3.25 D

3.00 0

April 25

Straw/Plant

6.44 A

5.16 B

4.80 B

4.55 BC

4.66 C

4. 7 0 C

4.53 C

4.35 0

4.15 E

4.26 E

4.25 0

4.31 0

4. 3 0 0

* Values followed by the same letter w i t h i n a c o l u m n are not sig n i f i c a n t l y d i f f e r e n t at the 0.05 level accor d i n g to

to the Student Newman Kuel Test.

' Dr y wei g h t s e x pressed in grams/plant.

T A B L E 8 . L e a f a r e a i n d i c i e s o f c o m m e r c i a l a n d e x p e r i m e n t a l l i n e s i n M e s a ,

1 9 7 8 - 1 9 7 9

Entry Feb. 1

Feb. 12 Feb. 22

Leaf 'Area 1ndex

M a r c h 5

M a r c h 14 Mar c h 22

April 9 April 13

Slete Cerros .48 A* 1.09 A

2.27 A 3.02 A 3.90 A

4 .33 A

3.50 A 2.64 A

MSF R S Se. PI. Bulk

.56 A

1.70 A 1.97 A

2.71 B 3.46 B

4.2 0 A 3.52 A 2.78 A

AIM

.55 A

1.49 A 2.01 A 2.63 BC

3.10 C 3.95 AB 3.19 A

2.28 A

Cajeme 71 .50 A

1.55 A 1.63 A

2.28 DE 3.74 A

3.96 AB 3.07 AB 2.16 AB

M S F R S Large Seed .42 A

1.21 A 1.81 A

2.43 BCD 3.09 C 3.69 B

3.00 ABC 1.98 B

MSFRS Early .38 A

1.03 A 1.73 A

2.25 DE 2.45 E

3.30 CD 2.73 ABC 1.80 BC

GABO .37 A

1.14 A 1.65 A

2.08 EF 3.01 C

3.28 CD 2.6 0 ABC 1.92 B

P1CTIC 62

.63 A 1.56 A

2.18 A

2.33 COE 3.12 C 3.24 CO 2.47 ABC

1.67 BC

ARVANO

.42 A 1.01 A

1.74 A

2. 0 0 EF 2.96 C 3 .06 D 2.3 0 ABC

1.41 BC

MSFRS Base .38 A

1.08 A 1.70 A

1.76 F 2.04 F

2.55 E 2.35 ABC 1.29 C

MSFRS Bulk Seed

.50 A 1.27 A

1.56 A

2.59 BC D 2.76 0 3.62 BC

2. 2 9 ABC 1.36 f.

Florence Aurore

.39 A

MSFRS Large Seed Cross .36 A

------------ -----

.93 A

--

.80 A

1.4/ A

1.98 II 2.29 1

1 .62 A 1.98 II

2.10

1

------ -- ------------------ * - — ---- -— * --— — — • •■ — - ----- . ......

2.45 I

2.20

I

1.79 C

1.94 C

— — - — — ---- -

* Values fo llo w e d by the same l e t t e r w ith in a column a re not s ig n if ic a n t ly d i f f e r e n t a t the 0 .0 5 le v e l acco rd ing to the Student Newman Kuel

1.28 0

1.09 0

— --- -— .

t e s t .

TABLE 9. Number of green leaves and % of green leaves at designated days after anthesis in Mesa, 1978-1979

Entry # of G. L.

0

% of G. L.

»

of G. L.

Days from anth e s i s

n

l

of G. L.

»

of G. L.

22

% of G. L.

I of G. L.

34

% of I

Siete Cerros

MSF R S S e l . PI. Bulk

AIM

19.6

20.2

20.3

17.5

Cajeme 71

M S F R S Large Sees

M S F R S Early

GABO

18.5

19.5

PICT1C 62

ARV A N D

18.5

20.4

22.0

MSF R S Base

MSF R S Bulk Seed

F lorence Aurore

18.0

20.0

20.1

MSF R S Large Seed Cross 20.5

100 A*

100 A

100 A

100 A

100 A

100 A

1 00 A

100 A

100 A

100 A

100 A

100 A

100 A

18.0

15.7

18.8

17.4

18.0

17.5

18.0

19.0

20.4

16.9

18.0

18.6

19.4

92 FG

78 1

93 OF

99 A

97 AB

90 GH

97 AB

93 OF

93 OF

94 BD

90 H

93 OF

95 BO

17.6

15.5

16.4

14.5

14.6

15.2

14.4

15.5

16.2

13.1

14.0

12.6

13.5

90 A

76 D

86 B

8 3 C

79 D

78 B

78 B

76 D

74 E

73 E

70 F

63 H

66 H

9.6

7.3

8.7

7.2

7.4

7.4

6.4

7.1

7.4

5.9

6.2

4.0

4.9

49 A

48 AB

43 AB

41 B

40 B

38 BC

35 BC

35 BC

34 C

33 C

31 CD

20 0

24 D

Due to v a riation in b l o o m i n g dat e s of e n t r i e s , the num b e r o f leaves at a n t h e s i s and at d e s i g n a t e d dates after a n t h e s i s for each e n t r y was e s timated

using the number of leaves at s a m p l i n g dat e s as input data and proje c t i n g the c o r r e s p o n d i n g num b e r at specific date aft e r anthesis.

* Values followed by the same letter w i t h i n a c o l u m n are not s t a t i s t i c a l l y di fferemt at the 0.0 5 leS/el a c c o r d i n g to the Student Newiian Kuel test.

M l

(Tables 7 and 5). Although other explanations may exist, this

suggests that the potential for grain production already is determined

by flowering, and investigations of the developmental anatomy of heads

at and before anthesis should be fruitful. In addition to providing .

ideas about the possible basis for yield differences, comparisons of

head and straw weights have given suggestion about the source of

assimilates required for grain development, In the 23 day intervals

from April 2 to April 25, head dry weight increased 3,8g for Siete

Cerros and lesser amounts for all other entries. In the same time .

interval, straw weights decreased but the decline represented only a

fraction (usually 10 to 20% but occasionally 30%) of the gain in head

weight. This suggests that assimilates required for ear growth are

largely products of ongoing photosynthesis or they have been

translocated from roots,

Examination of leaf area data showed that during early

February, LAI values of the different entries were alike, By early

^ferch, significant differences in LAI were found among the entries

(Table .8) and maximum values of LAI were obtained on March 22 for all

entries. At that time, LAI values of the high yielding Siete Cerros

(4.3) was about twice that of the lowest yielding MSFRS Large Seed

Cross. Highly significant correlations were obtained between LAI and

yield (Table 5) from March 5 onward,

Interestingly, anthesis and subsequent grain development

occurred after the peak in LAI, and during the later stages of grain

filling (e.g. 22 to 34 days after anthesis), there was a considerable

decrease in the number of leaves that remained green (Table 9).

42

Yields were significantly correlated to the ability of entries to

retain green leaves 34 days after anthesis- (Tables 5 and 9). These

results are in accord with those of Mohiuddin and Croy (39), who found

a high correlation between yield and leaf area- duration.

• I n evaluating the results as tools for predicting plant • response in Arizona deserts, it should be kept in mind that significant rainfall did occur during the growing season (Table 3)•

As a result, it is not possible to say how well, the plants would

conditions existing, during, the growing season are critical. A major

fraction of growth occurred at a time that temperatures were cool and

evaporational and transportations! demands were relatively low. If .

planting occurred 1 month later, or if plants differed widely in their

developmental pattern so anthesis of some entries occurred 2 to 3

weeks later, soil water profiles would have been depleted at a

critical period of growth, and yields may have been lowered

considerably (20.). In this study, all entries did reach anthesis at

approximately- the same time.

Taken as a whole, the study suggested that phenomenon

associated with head development are of great importance in

determining, yield of wheats grown with limited water. Significant

differences in yield were obtained among the 12 entries, but -

observations made during early growth showed little or no correlation

of yield with plant weights or leaf areas. As plants, approached

toward head development and this is when significant correlations were

43

found between.dry weight, head weight and leaf area index with yield.

Additionally, it was found that high yielding cultivars retained

leaves green for a longer period than low yielding entries.

All of the above criteria should aid in selecting for high

yielding plants. The above correlations also show the importance of

photosynthesis during head formation and grain filling, and they

suggest that efforts should be directed towards studying physiology

and anatomy as heads begin to form rather than at earlier periods.

44

Growth and Yield of Wheat under Limited Moisture Conditions

Mesa, Arizona, 1979-1980

Comparison of Yield and Yield Components '

respectable wheat yields can be obtained with minimal water (Table

10). The range in yield values (2350 to 3670 Kg/ha) was similar to

that obtained in the previous season (Table 4); additionally, entries

were ranked in the same order in both years. The average yields of

the high yielders, Siete Cerros and MSFRS Self Planting-Bulk, were

slightly higher, but productivities of the low yielders, Gabo, MSFRS

Base and MSFRS Bulk Seed, were somewhat less than in the previous season. The reason for these differences are not known but there may

be some relationship to planting date (Nov. 29, 1979 vs. Dec. 6, 1980)

or rainfall in the months of January and February (Table 3).

A comparison of grain yield with other yield components shows

there is little relation between grain yield and tiller number, number

of grains/spike, and blooming dates (Table 10) and this is reflected'

in low correlation coefficients (Table 11). In contrast, highly

significant correlations were found between yield and weight/1000

seed, number of grains/m2 and grain weight/spike (Table 11).

An examination of grain sizes in individual heads showed that

the high yielding Siete Cerros produced large grains in the first

three florets of the centrally located spikelets and the average grain

weights were between 50 to 60 mg (Fig. 4). This entry also produced

grains on the 4th and 5th florets of the centrally located spikelets,

TABLE 10. Yield (kg/ha) and yield components of commercial and experimental entries of wheat planted in Mesa, 1979-1980

Entry B l o o m i n g Date Yield kg/ha W t / 1 0 0 seed # g r a i n s / m ^

Siete Cerros

M SF R S Se. PI. Bulk

3/17

3/16

Toluca

A IM

3/14

3/13

3/12

M exicali

Cajeme 71

Anza

M S F R S Large Seed

3/11

3/13

3/10

M S F R S Early M a t u r i t y 3/10

PICTIC 62

3/12

GA B O

MSF R S Base

MSF R S Bulk Seed

3/11

3/14

3/13

36 7 0 A*

3309 AB

3238 ABC

3103 BCD

3022 BCOE

3007 BCOE

2922 BCOE

2765 BCOE

2660 BCOE

2580 COE

253 0 OE

2409 DE

2350 E

4 4 . 8 0 A

41. 4 0 AB

41.06 AB

40.67 ABC

40. 4 3 ABC

3 9.93 ABC

3 9. 9 0 ABC

39.30 AB C

38. 7 0 ABC

37.26 BC

37.17 BC

34.10 BC

33.70 C

# t i l lers/m^

6 0.03 A

56.89 A

64.71 A

6 5.86 A

66.53 A

80.17 A

67. 2 0 A

71.24 A

65.86 A

58.91 A

59.81 A

69.22 A

63.17 A

819 2 A

7992 A

7886 A

7629 A

7474 A

7530 A

7323 A

7035 A

6873 A

6924 A

6806 A

7064 A

697 3 A

# g r a i n s / s p i k e Wt. g r a in/spike

45. 0 8 A

44.41 A

40.54 A

41. 1 5 A

40. 5 2 A

38.40 A

39.97 A

37. 7 0 A

38.62 A

42. 0 2 A

41.05 A

4 2 . 5 0 A

4 1 . 8 0 A

3.136 A

2.788 AB

2.518 BC

2.542 BCD

2.466 BC

2.298 BCD

2.3 9 0 BCD

2.208 BCD

2.216 BCD

2.290 BCD

2.230 BCD

2.048 CD

1.980 0

* Values followed by the same letter w i t h i n a colu m n are not s i g n i f i c a n t l y diff e r e n t at the 0.05 level a c c o r d i n g to the Student Newman Kuel test

TABLE 11.

Correlation coefficients of y i e l d , yield components and growth parameter measured in M e s a , 1979-1980

Variable

15

16

17

18

4

5

2

3

1

Yield

Wt/(grain)/1000 seed

2

# of y r a i n s / m

# of g r a ins/spike

Wt (gram)/spike

9

6

<f of ti 1 lers/m2

1

LAI 2 / 2 0 *

a

Total Dry Weight 2/20

LAI 3/2

10

1 1

12

13

Total Dry Weig h t 3/2

LAI 3/19

Total Dry Weight 3/19

Head Dry Weight / p l a n t 3/19

14

Straw Dry Weight / p l a n t 3/19

Total Dry Weight 4/IT)

LAI 4/10

Head Dry Weight / p l a n t 4/10

Straw Dry Weight / p l a n t 4/10

.96

.74' N.S.

N.S.

N.S.

.62'

5 6

7

8 9

10 11 12 13

14 15 16

17

18

95** N.S.

.7)"

91*'

. w " ‘ .n il"

.64

'

.9 5 " .91)" .9 7 " . 6 ?

N.S.

.8011

. , 6 "

.85*' .03" .9 2 " .88*' .91*' . 6 6 S .8 8 "

.94"

.9 3 "

N.S.

6 8 b N.S. N.S. N.S. N.S. N.S. U.S. .58S .70" N.S.

.76*' .7l" .71*' .63s

5tiS N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. M.S. N.S. N.S.

N.S.

.57S .67** .69" .71" .82" .79" .9011 N.S.

.84" .92" .89" N.S.

N.S. N.S. N.S. N.S. U.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.

.79" .97" .83" .ill" .71)" .67S

. 6 8 "

.7l" .73" .74" N.S.

.8011

. 8 , "

.74" .60S .64S N.S.

. 6 I S . 6 8 " . / o "

N.S.

.85*' .88" .

80

" .76" .64S .77" 8 0" .80" N.S.

.84*' .73" .04" U.S.

,7l" .87*' .84" N.S.

.Ol" .92" N.S.

.84" .92" .92" N.S.

, 8 l " .9011 .95" . 8 6 " ,90" .76"

N.S.

.07" .91)" .97" N.S.

./ll" ,57s .63S .8l"

.9l" .94" 8 , "

.98" N.S.

.56"

H Highly signicant co r r e l a t i o n at 0.01 or lower

S Significant corre l a t i o n c o e f f i c i e n t at 0.05 level

N.S. Not signigicant at 0.05 level

* Ref e r to Table 5 for d e f i n i t i o n

1 <>

2 o

it

SIETE CERROS

5 10 15 20

SPIKLET NUMRFR

FIG. 4 Weight of individual grains from a head of a high during the 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain numbers of the head were 3.06 g, and 52 g r a i n s , respectively.

48

but the latter were smaller. In contrast, the low yielding MSFRS Bulk

Seed produced only 3 grains/spikelet and the average grain weights

produced by the centrally located spikelets were between 30 to 40 mg

(Fig, 5), These patterns were very similar to those obtained in the

previous year (Figs. 2 and 3).

Crop Growth Analysis

Total above ground weights increased continuously from the

first (Feb, 20) to the last (April 10) sampling dates, and entries

which ultimately yielded higher grain weights were normally larger at

all sampling periods (Table 12), A highly significant correlation was

found between yield and dry weight on Feb, 2 and the degree of

correlation became even stronger with time (Table 11), The highest

coefficient of correlation was obtained with the April 10 sampling

which was 1 month after anthesis. These results suggest that general

plant size during later growth stages is a good indication of yield,

Head weight differences among entries closely paralleled yield,

differences (Table 10 vs. Table 13) and highly significant correlation

coefficients were obtained between head weights on March 19 and April

10, and grain yields (Table 11). Significant correlations of yield

and straw weights at the above dates were also found (Table 11). The

correlation values obtained on March 19 suggest that the potential for

grain production is "set" quite early but the relation of straw weight

to yield is less clear. '

Examined in another way, most entries increased about 1

gram/plant in dry weights between March 19 and April 10 (Table 12),

MSFRS BULK SEED

0

2

1 g

5

5

s

U.

o

1 o

o

2

<► <>

• *

<>

5 10 15

20

SPIKLET NUMBER

FIG. 5 Weight of individual grains from a head of a low yielding cultivar grown under 'dryland' conditions in Mesa during the 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain numbers of the head were 1.85 g, and 43 grains, respectively.

TABLE 12. Total above dry weights of commercial and experimental lines of wheat grown under

'dryland' conditions in Mesa, 1979-1980

Entry T O W 2/20

Gr a m d r y w e i g h t s at indicated samp l i n g dates

T O W 3/2 TOW 3/19 TDW 4/1 0

Siete Gerros

M S F R S Self. P l a n t i n g Bulk

Toluca

A I M • • '

Mexicali

Cajeme 71

Anza

M SFRS Large Seed

M S F R S Early Ma t u r i t y

P ICTIC 62

G ABO

MS F R S Base

1 .

M S FRS Bulk Seed

2.75 A * 1

2.48 AB

2.2 8 BCD

2.23 BCD

1.50 D

2.58 A .

2.18 CD

2.05 D

2.33 ABC 6

2.40 ABC

1.65 0

. 1.44 D

1.08 E

4.03 B

4. 1 9 A

4.01 B

4.07 B

3.52 E

3.88 C

3.74 D

3.68 D

3.52 F

3.41 E

3.02 G

3.25 F

2.02 H

7.00 A

6.84 AB

5.80 DE

5 .59 E

6.45 C

6 .70 B

5.90 D

5.74 DE

5.03 F

4 .52 G

5.00 F

4.37 G

4 .33 G

8 . 5 3 A

7:95 AB

7 .6 0 B

6.4 8 C

7 .23 B

7.65 B

6 .45 C

5.94 CD

5.35 DE

5.03 E

5.18 E

4.74 E

5.05 E

* Values followed by the same l etter w i t h i n a c o l u m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0.05 level a c c o r d i n g to S tudent Newman Kuel test.

' D r y w eight e xpressed in grams/plant.

o in

TABLE 13. Dry weights of heads and straws of commercial and experimental lines of wheat planted under 'dryland' conditions in Mesa, 1979-1980

E ntry

Head Dry W e i g h t / p l a n t 3/19

Dry we i g h t s at indicated samp l i n g dates

S t raw Dry W e i g h t / p l a n t 3/19 Head Dry W e i g h t / p l a n t 4/10 S traw Dry W e i g h t / p l a n t 4/10

Siete Cerros

M S FRS Self P l a nting Bulk

Toluca a i m

Mexicali

C aj e m e 71

Anza

M S F R S Large Seed

M S F R S Early M a t u r i t y

PICTIC 62

GAB O

M SFRS Base

MSFRS Bulk Seed

2.35 A * 1 .

2.3 9 A

2.15 AB

2.25 A

2. 0 0 BG

1.67 D

1 .88 C

1.48 DE

1.52 DE

1.44 DE

1.30 EF

1.18 FG

1.02 G

4.65 B

4. 4 5 BC

3.64 E

3.34 FG

4.4 5 BC

5 . 0 3 A

4.02 D „

4.26 C

■ 3.51 EF

3.08 G

3.70 E

3.19 G

3.32 FG

4.70 A

4.86 A

4.24 B

3.97 C

3.70 D

3.68 D

3.65 D

3.20 E

3 .00 E

2.60 F

2.51 F

2.2 0 G

2.08 G

3.83 A

3 .09 C

3.36 B

2.51 EF

. 3.53 B

3.97 A

2.80 D

2.73 DE

2.35 F

2.43 F

2.67 DE

2.54 EF

2.97 C

* Values followed by the same l e t t e r w i t h i n one colu m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0.05 level a c c o r d i n g to the Student New m a n Kuel test.

1 Dry w e i ghts expr e s s e d in grams/plant.

52

In this interval, head weight, increases were about 2 grams and straw

weight decreases were about 1 gram (Table 13), The decrease in straw

weight may have been due largely to loss of leaves since LAI was

higher on March 19 than April 10 (Table 14). It seems unlikely that

translocation of materials from senescing leaves is a major

contributor to grain development, rather, increases in grain weight

must come as result of photosynthesis which occurs during the grain

filling period.

LAI values were determined at four periods during the growing

season (Table 14). Highly significant correlation coefficients were

obtained between LAI and yield at all sampling dates (Table 11), but

coefficient values increased as plants became older, These high ■

correlations suggest that photosynthesis prior to anthesis as well as

during grain filling may be critical for high yields. This is in

accord with findings of Boyer and McPherson (11).

in Mesa, 1979-1980

E ntry

Siete C erros

M S F R S Self P l a n t i n g Bulk

Toluca

A I M

Mexicali

C a j e m e 71

Anza

M S F R S Large Seed

M S F R S E a rly M a t u r i t y

P 1 C T I C 62

GAB O

M S F R S Base

M S F R S Bulk Seed

LAI 2/20

2 . 342 B+

2 . 302 B

2 . 262 BC

2 . 156 CD

2 . 0 9 8 0

. 2 . 588 A

2 . 1 3 0 CD

2.044 0

2. 2 5 8 BC

1.848 E

2. 032 GO

1.664 F

1.288 G

LAI 3/2

2 . 5 8 8 AB

2 . 5 7 2 AB

2 . 5 0 2 ABC

2. 4 0 6 BCD

2 . 378 B CD

2.734 A

, 2 . 2 1 8 CO

2. 102 0

2. 3 6 8 BCD

2. 0 9 8 D

2. 2 7 2 B CD

1.712 E

1 . 3 5 0 F

. LAI 3/19

3.178 A

3 . 145 AB

3 . 040 AB

2.992 ABC

2 . 9 0 0 AB

2. 7 8 8 A

2 . 5 4 0 A B C O

2 . 3 2 0 BCD

2 . 852 ARC

2.304 B CD

2 . 098 CD

1.844 D

1.666 D

,

LAI 4 / 1 0

2.524 A

2 . 362 A

2.244 AB

2.254 AB

2 . 1 1 0 ABC

1.992 ABC

2.034 ABC

1 . 8 1 8 BCD

1.802 BCD

1. 652 CD

' 1.626 CD

1.612 CD

1. 358 D

* V alues follo w e d by the same l e tter w i t h i n one c o l u m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0.0 5 level a c c o r d i n g to the S t u dent N ewman Kuel test.

54

Growth and Yield of Wheat under Different Irrigation Regimes

Tucson, Casa Grande Overpass Farm, 1979-1980 .

Comparison of Yield and Yield Components

The experiments at the Casa Grande Overpass Farm were designed

partly to determine if wheat can be grown with minimal water in a

location other than "Mesa; additionally, studies were conducted to

determine the effectiveness of a single additional irrigation at

different periods of growth. The close proximity of the field to the

laboratory also permitted a study of plant water status during the

course of the growing season.

Six entries were selected on the basis of their past

performance at Mesa, Arizona. Siete Cerros and Zargoza were

consistently high yielders whereas AIM and Cajeme 71 were intermediate

and Arvand aid Florence Aurore were low performers. The seventh

entry, Ramona 50 is an early maturing plant which was grown

extensively in the past in Arizona.

When watered only with a pre-planted irrigation and rainfall,

yields (Table 15) were generally lower in Tucson than'in Mesa (compare

Tables 4, 10 and 15) but performance rankings of the entries were •

maintained; additionally, even Florence Aurore, which is the lowest

yielder of the entries grown in Mesa, was clearly superior to Ramona.

Yields of all entries were highest when plants received the

recommended amounts of irrigation but all entries benefited by a

single irrigation (Table 15), and .irrigation on March 11 was more

'beneficial than water application on March 24. These results are in

TABLE 15. Yield of commercial entries of wheat grown in Tucson under different irrigation regimes

E n try

Zaragoza

Slete Cerr o s

A IM

Cajente 71

A R V A N D

F l o r e n c e A u r o r e

R am o n a

Yield

Minimal W a t e r (150 kg/m^)

2955. A*

2815. A

2552. AB

, 2288. BC

1989. Cl)

1747. D

1086. E

(kq/ha) of w h e a t u n d e r d i f f e r e n t i r r i g a t i o n reg i m e s

3/11 Irr i g a t i o n T r e a t m e n t

3/24 Irr i g a t i o n T r e a t m e n t

(225 k g / m 2 )

3635. A

3413. AB

3463. A

3642. A

2979. B

2449. C

2330. C

(225 k g / m 2 )

3347. A

3272. A

2964. A

2565. A

2311. AB

2174. BC

1646. C

Well I r rigated T r e a t m e m t

(525 k g / m 2 )

4702. A

4636. A

4491. A

4029. A

3746. AB

2886. B

2695. B

* Val u e s followed by the same l e t t e r w i t h i n a c o l u m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0. 0 5 level a c c o r d i n g to the Stu d e n t N e w m a n Kuel test.

56

accord with Fischer’s findings (20, 21) that application of water

about 2 to 3 weeks before anthesis is most critical for high grain

production. Except for Ramona, which flowered on March 25, flowering

occurred about 3 weeks after the first irrigation and 1 week after the

second (Table 16), Interestingly, a single irrigation on March 11

more than doubled, the yield of Ramona over that of the ’dryland’.

In order to gain a better.understanding of the basis for yield

differences, some of the components contributing to yield were

examined (table 16). The data show that irrigation usually delays

anthesis about 3 to 5 days and sometimes even a week. In addition,

the March 24 irrigation, which provided additional water during grain

filling „ mainly tended to numerically increase grain weight/spike and

grain number/unit area. The March 11 irrigation, which provided

additional water during flower formation, increased grain numbers/unit

area and in some cases number of grains/spike. Fertile tiller number

were increased in all. trials in which additional water was used and

the increases were especially evident in the control where the number

of tillers was about 30% more than the 'dryland' treatment. When

water was added throughout the season, increases in grain yield,

occurred because of increase in grain weight/spike and number of

grains/unit area. In the case of Ramona, a single irrigation on March

11 nearly doubled the grain size and weight of grain/spike (Table 16),

A summary of the yield and yield component data reveals that

(a) grain yields increased with irrigation (b) if.a single irrigation

is used, the best time is 2-3 weeks before the estimated time of • anthesis, i.e. Feekes .Scale 7 through 8 under the conditions of this .

TABLE 16. Yield components of commercial entries of wheat grown under different irrigation regimes in Tucson, 1979-1980

---------- ;-------------- '------- — --------------------- ?j--------- —

Minimal Water (150 kg/ m H q

O)

: - - : ‘

3/2 4

.......... ......... ............. ......... ..................:...................... ....

ili t ( 2 25 kg/m__^ O )

Entry B l o om in g W E ( gr am s)/ ^t illers/ ^grains/ ^grains/. W E (gr am s)/

Date 1000 seed m^ m^ spike spike

B l o om in g W E ( g r a m s )/ i E i l l e r s /

tigra

ins/ ^grains W E ( g r a m s )/

. Date 1000 seed m^ spike spike

Zaragoza

Siete Cer r o s

AI M

Caj e m e 71

A R V A N D

Flor e n c e A u r o r e 4/2

Ramona 50

4/1

P/3

3/30

3/31

4/2

3/25

4 1 . 0 0 A*

4 0 .56 A

4 0 . 0 0 A

33.06 B

30 . 0 0 C

25 .56 D

18 . 0 0 E

61, 0 A

57. 0 A

54 . 0 A

56.0' A

43 . 8 A

47.1 A

4 3 . 0 A

7231 A

6944 A

6384 A

6935 A

6 7 2 0 A .

51.1

AB 1.51 B

6 9 8 9 A 49.3

AB 1.24 C

604 8 A

50.0

AB 2.04 A

56.1

A 2.28 A

4 0 . 9 B

4 9 . 9 AB 1.65 B

46.8

AB

1.64 B

.88 B

4/7

4/6

4/6

4/4

4 / 1 0

4 /9

4/1

4 7 . 0 0 A*

45 . 9 2 A

43.14 A

4 2 . 6 0 A

3 6.08 B

33 . 6 0 B

2 7.48 C

66.0- A

58. 0 AB

53.0' AB

4 7 . 0 B

5 7 . 0 B

7123 A

7137 A

58. 0 AB 7513 A

7607 A

7661 A

5 4 . 0 AB 67 6 6 A

6 7 2 0 A

4 8.9

AB 2.30 A

4 4 . 0 BC 2.40 A

55.1

A 2.28 A

40.1

BCD 1.71 B

55.3

A 2.00 A

38.6* BCD 1.30 C

31.4.

D 1.05 C

Entry

Zaragoza

Siete C e r r o s

A I M

3/11 Irrigation T r e a t m e n t (225 k g / m h

2 o

)

B l o o m i n g Wt ( g r a m s ) / i t l l l e r s / ^ g rains/ dfgrains/ W E ( g r a m s ) /

Date 1000 seedm^ m^ spike spike

4/5

4/5

4/4

Ca j e m e 71

A R V A N D

4 /3

4/4 .

Florence A u r o r e

4/6

Ramona 50 3/28

3 3 . 2 0 AB* 6 7 . 0 0 A

3 0 . 8 0 AB

2 9 . 5 0 B

31.84 AB

34.04 AB

36 . 0 0 A

3 5 . 0 0 AB

6 1 . 0 A

6 5 . 0 A

68.0. A

70. 0 A

53 . 0 A

6 1 . 0 A

11021 A 61.1

A

10657 A 56.6

A

11747 A 6 1 . 6 A

2.29 A

1.74 B

1.82 B

11591 A 58.4

A 1.86 B

8711 B 46. 2

BC 1.51 B

7129 B 4 2 . 0

0 1.57 B

6854 B 45.4

BC 1.59 B

Well W a t e r e d T r e a t m e n t (525 kg / m ^ H o0)

B l o o m i n g

Date

4 / 1 0

4 /8

4/8

4 / 8

4/8

4/9

. 4/4

W t ( g r a m s ) / J t l l l e r s /

1000 seed

3 5 . 0 0 A*

3 9 .78 A

3 6 . 3 0 A

38 . 0 0 A

3 7 .16 A

3 6 . 1 0 A

3 2 . 5 0 A m

. ^grains/ m 2

^gra ins/ spi ke

Wt(gr a m s ) / spike

9 4 . 0 A T3444 A 60.0

A 2.10 A

83,0. AB 11661 AB 58.1

A

2.31 A

9 3 . 0 A

75.0' B

8 5 . 0 AB

63.0= B

72 . 0 B

1 2 3 8 0 A 48.8

A 1.77 AB

10611 AB

10088 AB

59.3

48.0*

A

A

2.25 A

1.78 AB

8 0 0 0 B 43 . 2 A 1.56 B

8 2 8 2 B 43.0

A 1.40 B

* Values f o l l o w e d by the same letter w i t h i n a c o l u m n are n ot s i g n i f i c a n t l y d i f f e r e n t at the 0.05 level a c c o r d i n g to Student. Newm a n Kuel test.

58

experiment (Tables 15 and 16), (c) irrigation which provides water

during grain filling will increase yield only slightly, mainly due to

production of heavier spikes (Table 16) whereas (d) irrigation

provided earlier, during the time of grain formation will increase

yield by producing more grains/spike. Thus, earlier irrigation

appears to slightly increase tiller numbers, but the numbers are

considerably less than from values found .for well watered plants .

Under ’dryland’ conditions (Table 17) highly significant

correlation coeffients were found between.yield and grain weight/1000 .

seed (r=,99) and grain weight/spike (r=,97) and significant relation

was noted between yield and number of grains/m2/(r=,75), but there

was no relation of yield with number of grains/spike or number of

tillers/unit area. These trends were nearly identical to those

obtained for the 1979-1980 season at Mesa (Table 11), and in general

components (Table 19) were nearly identical to those of entries from

weight/1000 seeds and grain weight/spike, correlated significantly to

grain number/unit area but not to grain numbers/spike or tiller

numbers/area, A very different relationship of yield to yield

components was found in plants that were irrigated 3 weeks prior to

flowering (Table 18), As in other studies in which plants were

growing on less than optimal water, tiller numbers were not correlated

with yield; however, grain number per m2 or per spike were more

TABLE 17. Correlation coefficients of various plant developmental characters with yield and with each other when grown on minimal water (150 kg/m^)

1

Yield

2 W e i g h t / 1000 seed

3 # of g r a i n s / m 2

4

k

g r a ins/spike

5 Grain Wt/s p i k e

6

# t i l l e r s / m 2

7 LAI 2/17

0 Total Dry Wei g h t 2/17

9

Total Dry Weight 2/29

10 LAI 3/14

11 Total Dry W e i g h t 3/14

12 Head Dry "eight 3/14

13 Straw Dry Weight 3/14

14 Total Dry Weight 3/28

15 LAI 3/28

16 Head Dry Weight 3/28

17 Straw Dry Weight 3/28

18 LAI 4/10

19 Total Dry Weight 4/1 0

20 Head Dry Weight 4/10

21 Straw Dry Seight 4/1 0

22 Head Dry Weight 4/22

23 LAI 4/22

24 Total Dry Weight

25 Straw Dry Weight 4/22

H Highly S i g nificant at 0.01 level or lower

S S i g nificant at 0.05 level

N.S. Not Si g n i f i c a n t at 0.05 level

* Refer to Tuble 5 for d e f i n i t i o n

1 2 3

4 5 6 / 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

.9 9 H .75S N.S. ,97H N.S. N.S. N.S. N.S. N.S. N.S. .92H N.S. .9 4 H . 90*' . 94 H

.9o " .96" .93" .96" .88" .96" .95" .93" .85"

N.S. N.S. .94H N.S. N.S. N.S. N.S. .71S N.S. .93*' N.S. .9l" .91H .92" ,86H .94" ,90" .93" .84" .93" .92" .89"

8l "

.73S .78S N.S. N.S. N.S. N.S. N.S. N.S. .74S N.S. .72S N.S.

.8IH N.S. N.S. .72s .8l" N.S. .76S ,8l" .76S .73S

.71S N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.

N.S. N.S. N.S. N.S. N.S. N.S. .87H N.S. .93 H .89H ,90H .90" • 97 H .94" .94" .90" .95" .89" .95" ,90"

N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.

N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. M.S.

N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. M.S.

N.S. N.S. .76S N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.

N.S. N.S. N.S. .72S .89H N.S: N.S. N.S.

.72S N.S. .72s .72S N.S. .74S .73S

N.S.

.91H N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.

N.S. .80S .79S .97H .71S .89" .81S .92" .73S .89S .94" ,83S .72S

N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S. N.S.

.93" .8811 .99H .96" .99" .95" .99" .98" .9l" .99" .95"

.83S .92H .93" .93" .89" .93" .93" .84" .93" .89"

.80S .93" .90" .98" .83S .95" .99" .9l" .83"

.92" .98" .90" .99" .95" .84S .96" .95"

.97" .96" .94" .93" ,9l" .96" .90"

.97" .99" .99" .92" .99" .96"

.92" .99" .98" .97" .97"

.96" .85" .98" .97"

.96" .99" .94"

.95" .85"

.98"

TABLE 18. Correlation coefficients of various plant developmental characters with yield and with each other measured on 3/11 irrigation treatment

(225 k g / m 2 H 20)

1 f i e l d

Z W e ig h t (g r*a i)/IO O O seed

}

3

I G r a in s / *

1

1

G r a l n s / s p l l e

5 G r a in W e lg h l/s p lk e

6 1 t l l l e r s / m ' ’

r

i a i z / i / n t o t a l O ru W e ig h t 2 / I f

9 lo t a 1 D ry W e ig h t 2 /2 9

10 I A I 3 /1 4

I I I t o a l D ry W e ig h t 3 /1 4

12 Head O ry W e ig h t 3/1 4

13 Head D ry W e ig h t 3 /1 4

14 l o t a l D ry W e ig h t 3 /2 8

IS I A I 1/28

16 Head O ry W e ig h t .1/28

1 / S tra w D ry W e ig h t

18 LAI 4 /1 0

19 l o t a l D ry W e ig h t 4 /1 0

20 Head D ry W e ig h t 4 /1 0 •

21 S tra w D ry W e ig h t 4 /1 0

22 Head D ry W e ig h t 4 /2 2

23 I A I 4 /2 2

24 l o t a l D ry W e ig h t 4 /2 2

25 S tra w Ory W e ig h t 4 /2 2

II H ig h ly s l g i i l c j l c m t « t 0 .0 1 o r lo w e r

S S i g n i f i c a n t a t 0 .0 5 le v e l

N .S . Not s i g n i f i c a n t a t 0 .0 5 le v e l

18

1 2 3 4 5 6 7 8 9 10 I I 12 13 14 IS 16 17 19 20 21 22 23 24 25

-

,8 2 s .9 8 » " .9 4 i r ^ 5 7 i . - i i . r 7 r . T r

.78S

. 8 I S M .S.

. 9 l " a a " M S . M S . N .S . M .S. M S .

M .S . M .S. M.S. N.S

.9 7 U ,7 5 s

M.S. M S M .S . M S .

8 4 " 73s 74S M.S.

. 9 2 " T 9 l f T s "

78S

M .S.

. 9 . " " W

76s M.S.

8 2 ^

9 4 " l o s M.S.

76s M.S. M.S.

.7 8 S .7 8 S 72s M .S . M .S. M S .

92» .8 9 " 8 3 S M.S.

. 9 0 " . 9 6 " ,7 7 s M .S. .8 2 " .9 4 "

76s 76S

B2S ■ 73s

. 9 o " ,8 2 s

.8 4 " M .S. M .S. M .S . M .S.

M .S. M S . M .S . .7 8 S

B2S

9 fl"

8 4 "

9 9 "

74s .9 2 "

.8 7 " .8 4 "

. 9 l " .8 6 " M S .

8 2 S .8 7 " M S .

. 9 l "

8 2 s

9ZM .8 0 S

8 3 s

73s .8 7 " .9 5 "

82 S M.S.

7 . S M S .

.8 4 " .8 8 " M.S. M .S.

M.S. M .S . M .S.

M.S.

M.S. M.S. M .S. M.S. M.S.

M.S. M.S. M.S.

M S .

M S . M .S. N .S . M.S. M.S. N S.

M .S. M.S.

N .S .

M.S. M .S. M S M S .

N .S . M.S.

M.S. M S .

M S .

M.S.

M .S. M.S.

M S .

M S .

M .S.

74S M.S. M.S. M S .

M.S.

M.S.

75S 72s 8 3 S M.S. M .S.

74S ,7 6 s M.S. M.S. N.S. M.S. M.S.

75S .8 3 "

77s N S

M S

8 6 " . 8 1 " M S .

,7 6 s M S .

M S

M.S.

76S M .S. M.S.

.8 2 S B2S .7 6 S

. 9HM .9 6 "

.8 ? "

77S .7 7 S ,7 3 s M.S.

8 I S . 8 5 " 8 2 s M.S.

72S .7 8 S M .S. M .S.

.8 5 " .7 8 S M .S. M .S.

73S

83s M.S. M S .

8 I S .8 9 " M.S. M.S.

8 3 S . 8 I S a s " M.S.

7 I S .8 2 S , 7 I S M.S.

8 1 s

8 2 S ,7 0 s M .S.

8 3 S 8 7 " M .S. M.S.

M IS M.S. M .S. M .S.

, 7 I S .8 4 " M.S. M.S.

. 9 5 " .9 ( l" . 7 I S .9 2 " 9 9 " 9 4 " 79s .9 8 " .9 3 " .9 6 " 8 2 S

. 9 3 " M.S.

.9 5 " .9 3 "

M.S.

9 o " .7 9 " 9 l " .9 3 " e g " 76$ lie " .9 8 "

M.S.

9 6 " 8 0 S .9 9 " 8 6 " . 95" B . S

73s M.S. M.S.

,7 3 s M.S.

,7 u S M .S.

8 7 " 8 3 S

8 4 S .8 7 " . 9 h

" ,8 0 s M.S.

9 5 " 8 0 S .9 6 " 8 9 " .9 6 " .8 4 "

.8 7 " .9 7 " 79s .9 9 "

8 3 S 77s

,9o"

79S M.S.

.8 3 " .9 8 " 8 I S

78s M.S.

.9 4 "

TABLI: 19. Correlation coefficients of various plant developmental characters with yield and with each other measured on 3/24 irrigation treatment

(225 k g/m2 ll20)

1

,

H o l d

7

Wo 1 ,,1,1/ 1000 te o .l

1

4

5

1 o f q r a ln s /m ^

1 o l c , r * l, is / < | il1 e f i r a l n w o i y l l l / s p l t o

6

;

n

f) f o l I I I l o r t / * /

I / l l 7 / 1 / l o l a 1 ll r y W o |,,|,| 7 /1 / l o l a l II. y W o ly l.l 7 /7 9 in M l

1 /M

H l o l a l II, y Wo 1,,1,1 1/11

IZ Ik ad II, y Wo 1 y l i l 1 /1 1

11 S tra w l l r y M o lc ilil I / M

M l o l a l l l r y W o l,|h l 1/711

IS M l 1/7 0

If. llo .M Hi y Wo 1..1.1 1 /7 0

1/ SI raw ll r y Wo 1,,1.1 1/711

in M l 1 /1 0

I ' i l o l a l Ory W oiijl.1 1 /1 0

70 lle a -l ll r y Wo I , ,1,1 a / 10

71 S tra w O ry W o In h l 1 /1 0

77 llo a .I D ry Wo 1,,1,1 1 /7 7

71 M l 1 /7 7

71 l o l a l O ry Wo I,,h i 1 /7 7

75 l o l a l S tra w O ry W o ly l.l 1 /7 7

II l l l i | M y O i p i l ( l i i t H t i l l 0 .0 1 I r v e l o r lo w o i

S

S l q o l f l c » n l » l I f . Of. lo y o l

M .S . Mol t l i | » l l l t » o l 0 OS I r v o l

7 1 1 S

6 7 0 9 10 I I 17 11 11

IS 16 17 10 70 71 77 71 71 7S

V 7 7 * M S 9 l " M S M S M S M S .

. 7 1 '

. 7 ft' 117' M .S . 9 l " I I I " 9 7 " 9 7 "

.

0 , " 97 "

9 ? "

O l" 119 " 9 l " 8 9 " 7 9 '

M S M S .

9 , " M S

/ 6 S M S M S

M .S . M .S . . 7 ? '

M S

8 7 " M.S. M S

M S M S

II S

M S

M S

N S

M S

N S

. 7 1 '

M S .

M S

M S .

O l"

M S

M .S.

M.S.

7HS M .S. 9 / "

M S .

M S M S m a' M .S. M S . M.S. M S

97 "

M S O l '

9 l "

Of,"

N S. M S

7 6 ' IV ."

.

9s"

M S

M S .

n o '

O l '

M S.

in i'

. 9s"

M S .

. . . '

9 7 "

H S.

M S .

M S.

M S

.116"

97 "

M S .

7 / '

.9 0 "

II S.

M S .

N S

.9 6 "

N S

9 1 " o s "

M S .

N S M S

O l " . 8 9 "

II S.

N S.

7 6 ' M S

M S. M .S. M S. M S .

M S n V M S. M.S.

M S

M S

M S

M .S. M S

M S N S

. 7 1 ' M S .

M S

.

7 , ' M

s

M.S.

M S M S

7 s ' M .S.

M S N S

7 7 ' M S. M S

M S .

M.S.

N 5

. 7 1 '

- B o '

M .S . M S .

-

7 9 ' II s M .S .

M .S.

M S M S .

M.S.

M .S. M .S.

M S M S .

M S .

M S

N S. M S

M .S . M .S.

M .S.

M S

M .S.

M .S . O l ' »*.*».

7 l '

I l l ' M S

. / a ' . 7 9 ' / o '

I l l l ' 7 l '

7 7 ' M .S.

9 , "

M S

II . S

. 7 ? ' 7 h '

M l ' 0 / "

01." M S

. 96"

H i '

76S .8 7 "

H i '

7 , ' III , "

. / s '

O l ' 7 / '

7 l '

os"

I I I ' *• 0 "

os" on" on"

0 6 "

O il"

Oh"

M .S . 7 7 ' M.S.

. 7 1 ' M .S.

o s '

. 7 1 '

. 7 6 '

7 7 ' 79 ' H i " M S M.S.

M.S.

M .S.

M.S.

M .S.

M S M .S. M .S.

M S

M S

M.S.

N.S

M .S .

. 9 '," .9 7 " 9 9 " O l" . O il"

. 9 6 " 9 / " 9 9 "

Of."

9 7 "

Oil" on"

. O l"

on"

111" 9 . " O il"

. 9s"

91,"

9 7 " 9 l "

no"

O l ' 91,"

9 9 "

O f."

or."

119" Of,"

7 . '

79 ' 9 ll" .9 1 "

9 / "

97

"

is"

O il" 9 7 "

O il" 0 9 "

. 9 l "

.

O il"

99 " m " .91"

. 7 7 ' M S

.9 7 "

9 ll"

.9 7 " 9 ."

9 , " .

9 l " 9 7 "

nos

■8." •M,"

8 7 "

«1

86

-M."

closely correlated with yield than grain size or grain weight per

spike,

In the well-watered border, no relationship was found between

seed'Nsize and yield (Table 20). Rather, tiller and grain number per

unit area; and grain number per spike and also grain weight/spike were

all highly associated with yield.

Examination of heads from the high yielding Siete Cerros and

the low yielding Ramona entries provided ideas about how irrigation

can affect yield and yield components, Under ’dryland’ conditions,

the weights of grains produced by the first 3 florets of most

spikelets from the Siete Cerros head (Fig. 6) were somewhat more than

40 mg, but the weight of the 4th grain was considerably less, and a

5th grain was not produced. Centrally located spikelets did produce 5

grains in heads from borders which received water 3 weeks before

anthesis (Fig. 7) and also the well-watered border (Fig. 8). The head

from a plant which received water 1 week before anthesis did not

produce a 5th grain, but the grains produced by the first four florets

in a spikelet were on the average, much larger than those from any of

the other treatments (Fig, 9). These data are in line with the idea

that water deficits 2 to 3 weeks prior to anthesis can lead to reduced

meiosis of pollen mother cells.

In contrast to Siete Cerros, Ramona seems incapable of

generating a 5th grain and this may be one reason why its yield is

low. Ramona seems to be particularly sensitive to water deficits

since grain sizes under dryland conditions (Fig, 10) were about half

that of the Siete Cerros, Watering 2 weeks prior to anthesis (Fig.

TABLE 20. Correlation coefficients of various plant developmental characters with yield and with each other when grown on well watered

(525 kg/m2)

1 yield

2 W e tg h t/1 0 0 0 seed

3

I

G r . l n s / . 2

4

I

g r a ln s / s p U e

5 G r a in W e lg h t/s p lk e

6

I

U l l e r s / m Z

/ I A I 2 /1 7

B l o l a l D ry W e ig h t 2 /1 7

9 l o l a l D ry W e ig h t 2 /2 9

10 LA I 3 /1 4 .

11 lo t a I D ry W e ig h t 3 /1 4

12 Head D ry W e ig h t 3 /1 4

13 S tra w D ry W e ig h t 3 /1 4

14 l o t a l D ry W e ig h t 3 /2 8

15 LAI 3 /2 8

16 Head D ry W e ig h t 3 /2 8

17 S tra w D ry W e ig h t 3 /2 8

18 I A I 4 /1 0

19 l o t a l D ry W e ig h t 4 /1 0

20 Head D ry W e ig h t 4 /1 0

21 S tra w D ry W e ig h t 4 /1 0

22 Head D ry W e ig h t 4 /2 2

23 I A I 4 /2 2

24 l o t a l D ry W e ig h t 4 /2 2

25 S tra w D ry W e ig h t 4 /2 2

H H ig h ly s i g n i f i c a n t a t 0 .0 1 o r lo w e r

S S i g n i f i c a n t a t 0 .0 5 le v e l

M .S . N ot S i g n i f i c a n t a t 0 .0 5 le v e l

1 2 3 4

U.S. .9JH 84*

5

M .S. M .S. M.S.

?9S 92H

6

0SH

7

M.S.

8

M.S.

9

10 14 16 17 18

I I 12 13 IS 19 20 21 22 23 24 25

.7?

M .S.

0 3 S M .S.

. 8 8 *

TF

94** 8 3 S 9 4 " .9 4 " .8 8 * , 9 . " 8 2 S .92** M .S.

80 S M .S. M .S.

.8 6 " M .S. M .S . M .S. M .S. M.S. M .S. M S . M .S . M S .

M .S . M .S. M .S. M .S. M.S. M.S.

.7 7 S

.7 4 S M S .

.7 4 S M.S. M.S. M.S.

83S M.S.

.8 6 " 72S .9 1 " ,7 1 s 78S . 9 1 " .

89 " .8 9 " .9 3 *

76s

8 8 * M .S.

M.S.

9 6 " • 8 2 S

M .S. M .S .

M .S.

.7 6 S .7 o S 8 o S . 9 l " .8 7 " M.S.

.8 2 S M.S.

.9 3 " N S N S.

9 c " . 9 , " . 9 l " .8 8 * M .S.

.9 6 "

M.S.

M .S. M .S . M.S. M.S. M S . M .S. M.S.

.7 3 S M.S. M .S.

.7 3 S 72S . 7 I S

8 9 "

75S M.S. M.S. M S .

M .S.

8 9 " 8 4 " 9 3 " .8 2 S M.S.

8 0 S M .S.

9 0 " M S .

.7 3 " .9 0 " 9 , " .8 4 " . 8 I S M.S.

.9 3 " 9 5 *

.8 9 " M.S. M .S. M .S . M .S. M .S. M .S. M.S. M.S. M S . M .S. M.S. M .S.

,7 8 s .7 8 S M.S.

.7 4 S M.S.

M.S.

M .S.

M .S .

M.S. M .S. M .S. M.S. M.S.

.8 2 S M S M.S.

76S .7 2 S M .S. M.S.

.7 3 S

70S N S . N S

74S M .S.

.8 6 " . 8 I S M .S. M.S. M .S.

74S -7 5 S M S. N S M.S.

77S. 84 "

77S M .S.

.7 0 S 76S .7 6 S .7 3 S .7 3 S M .S.

.7 8 S M .S .

.7 2 S 8 3 S 8 I S M.S.

76S .7 3 S .7 3 S .8 6 " .8 5 " .8 3 S .7 3 S M .S.

.B o *

. 9 5 "

M .S.

, 8 I S H0S 9 5 " M S ?

72" .8 9 " 91S . 9 2 " 8 9 S .7 2 * 93S .7l"

M .S . M.S. M.S. M.S.

M .S. M .S. M .S . M S .

M .S . M .S. M .S.

76S

,8 0 S os" 95" 96"

.9 7 "

.9 5 " .9 4 " . 8 7 " 9 4 " . 9 , " .7 2 S

73S 73S 8 6 " .7 8 S 79S .7 4 S 8 3 S 8 3 s ,7 6 s M.S.

M.S.

76S .9 4 "

.9 5 " bb

"

.9 1 *

74S 9 6 " 77S

.9 4 " .85" 8 3 S .8 5 " .7 3 S .9 3 " 76s M .S.

.9 0 " .9 0 " 8 5 " 8 0 S .9 8 * 8 2 S M.S.

.9 9 "

.9 7 " .9 4 " .8 6 *

. 9 2 * . 9 l "

.8 8 *

. 9 5 *

9 8 " 8 0 S

9 8 " .8 2 S

78S .9 5 * .7 2 S

73S . 95** M.S.

.7 6 S M .S.

C7\

0 4

3*

O <>

SIETE CERROS

o

• •

*

* * •

*

* *

<> o

6 10

SPIKLET NUMBER

15 20

FIG. 6 Weight of individual grains from a head of a high yielding cultivar grown under 'dryland' conditions at the

Casa Grande Overpass Farm during the 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain numbers of the head were 2.15 g and

60 grains, respectively.

o\

-px

1 O

2 o n

RAMONA

<>

O <►

<>

o

o

5 10 15 20

SPIKLET NUMBER

FIG. 7 Weight of individual grains from a head of a low yielding cultivar grown under '3/11 irrigation t r e a t m e n t 1 conditions in Casa Grande Overpass Farm during the 1979-

1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain number of the head are 1.62 g and 46 grains, respectively.

o in

SIETE CERROS

SPIKLET NUMBER

FIG. 8 Weight of individual grains from a head of high yielding

Grande Overpass Farm during the 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain number of the head were 2.48 g and 59 grains, respectively.

SIETE CERROS

» 4

4

5 10

SPiKLET NUMBER

15 20

FIG. 9 Weight of individual grains from a head of a high yielding cultivar grown under 13/24 irrigation t r e a t m e n t 1 conditions at the Casa Grande Overpass Farm 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain number of the head were 2.40 g and 52 grains, respectively.

c

SIETE CERROS

5

10

15

20

SPIKLET NUMBER

FIG. 10 Weight of individual grains from a head of a yielding cultivar grown under

high

'3/11 irrigation t r e a t m e n t 1 at the Casa Grande Overpass Farm, Tucson, during the 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain number of the head

are 1.92 and 60 grains, respectively.

69

11) or close to anthesis (Fig, 12) or heavy watering (Fig, 13) clearly

increased the average size of the grains. The highest average grain

sizes were obtained from borders receiving adequate water or water

close to anthesis (Figs. 12 and 13) but these heads had only three

grains/spike.

The results must be considered preliminary since the number of

heads presented is limited, but they do suggest a way for studying how

stress might affect grain size and mumber.

Crop Growth Analysis

In order to determine how vegetative growth might be

influenced by various irrigation treatments and also to assess the

importance of vegetative growth to grain production, comparisons were

made of (a) the above ground total dry weights (Tables 21, 22, 23 and

24), (b) head and shoot dry weights (Tables 25, 26, 27 and 28), and

(c) leaf area indices (Table 29') of different entries. In all tables,

entries were listed in accordance with their yield performance.

Correlation coefficients obtained in comparisons of yield and other

morph©logial characters are given in Tables 17, 18, 19, and 20,

The above ground dry weights of all entries increased from the

first (Feb. 17) to the last (April 22) sampling date in all irrigation

treatments. On the final sampling date, dry weights of plants

receiving minimal Irrigation (Table 21) were substantially less than

comparable entries which received either of the two single irrigation

treatments (Tables 22 and 23) and entries in the latter treatments, in

turn, weighted less than those from the well-watered border (Table

RAMONA

20

SPIKLET NUMBER

FIG. 11 Weight of individual grains from a head of a low yielding cultivar grown under

’ limited m o i s t u r e 1*oi conditions in Casa Grande Overpass Farm during the 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1.

Total grain weight and grain number of the head are

.88 g

and

46 grains, respectively.

o

1 <>

2 o

3 4

RAMONA

tc

0

1

n

0

0 o o

& o iTi

5 ;0 15 20

SPIKLET NUMBER

FIG. 12 Weight of individual grains from a head of a low yielding cultivar grown under 13/24 irrigation t r e a t m e n t 1 conditions at the Casa Grande Overpass Farm during the 1979-1980 growing s e a s o n .

The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and number of the head were 1.20 g and 34 grains, respectively,

1 <►

2

*

3 o R A M O NA

*

#

*

*

<>

*

<>

<>

0 ~

8

4 ^

*

5 10 15

SPIKLET NUMBER

20

FIG 13 Weight of individual grains from a head of low yielding

Overpass Farm during the 1979-1980 growing season. The most basal spikelets and most basal florets in a given spikelet are designated as being number 1. Total grain weight and grain number of the head were 1.32 g and 44 grains, respectively.

K)

TABLE 21. Total above ground dry weights of commercial lines of wheat grown under minimal water conditions

Entry

Zaragoza

Siete C efros

A I M

C a j e m e 71

A R V A N O

Flor e n c e A u r o r e

Ramona 50

T DW 2/17

Dry weights; at d e s i g n a t e d samp l i n g dates

T D W 2/29 TDW 3/14

TD W 3/20

.50 C 1^

.05 A

.40 C

.70 B

.80 A

.90 A

.65 B

3

1.60 ABC I)

1.90 AB

2 . 1 0 A

1 .10 D

1.20 C D

1.00 ABC

1.40 B C D

2.2 0 B

3.15 A

2.00

0

2.20

0

2 .95 A i . 97 n

1.05 B

7.55 A

7.05 A

5.60 0

5.90 B

4 . 6 0 C

4 . 2 0 C

3.70 C

T DW 4/1 0

- 9.50 A '

9.32 A

6 . 9 0 0

7.20 B

5.30 C

5. 4 0 C

4.6 0 C

TDW 4/22

10.20 A

10.50 A

7 . 6 0 BC

0.5 0 0

6 . 1 0 CD

6 . 3 0 CD

5.20 0

1

Values f o llowed by the same lett e r w i t h i n a c o l u m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0.05 level a c c o rding to to. the S t u dent N ewman Kuel Test.

' " - '

2

'

2

2 .P lants r e c e i v e d 150 kg/ m (6 A c r e - i n c h ) o f p r e p l a n t ir r i g a t i o n and a b out 150 k g / m (5 A c r e - i n c h ) o f seasonal rainfall (see Table 3)

3 Dry w e i g h t s e x p r e s s e d in g r a m s /plant.

TABLE 22. Total above ground dry weights of commercial lines of wheat which received an additional irrigation on March 11

Entry

Zarag o z a

Siete Cerr o s

A I M .

Ca j e m e 71

A R V A N D

F l o r e n c e A u r o r e

Ramona 50

G rams

T D W 2/17

.87 A 1/2/3

.90 A

.70 A

.71 A

.75 A

72 A

.70 A

TDW 2/29

1.35 C

1.80 A

1.40 C

1 .30 C

1.5.5 B

. 1.25 C

1.10

0

T DW 3/14

2.85 BC

3.59 A

3.05 B

3 .00 B

2.60 C

2.75 C

2.63 C dates

TOW 3/28

7.10 A

7.34 A

6.26 A

6.52 A

5.05 8

4.51 B

4.2 0 B

T OW 4 / 1 0

11.50 A

11.60 A

9.7 0 B

10.20 AB

7.40 C

6. 2 0 C

6 . 6 0 C

TDW 4/22

14.95 A

13.08 B

11.67 B

12.26 B

9.62 C

9.06 G a. a n C

)

Values foll o w e d by the same l etter w i ^ f n A *\e c o l u m n a re not s i g n i f i c a n t l y d i f f e r e n t at the 0.05 level acco r d i n g to

' the S t u d e n t N e w m a n Kuel test. ^

2

Plants w e r e gi v e n a p r e p l a n t i rrigation and an a dditional i r r i gation (75 k g / m . =3 A c r e - i n c h ) on M a r c h 11 j

3 Dry w e i g h t s e x p r e s s e d in g r a ms/plant. .

TABLE 23. Total above ground dry weights of commercial lines of wheat which received irrigation on March 24

E ntry

Zaragoza

Siete C erros

AIM

Caje m e 71

A R V A N O

Fl o r e n c e A u r o r e

Ramona 50

G r a m d r y - w e i g h t s at d e s i g n a t e d s a m p ] i n p dates

TOW 2/17 TOW 2/29 T DW 3/14

TDW 2/28

- - , 7 , 0 7 / 2 / * "

1.30 A

.95 AB

1.36 A

.50 1)

.91 ABC

.85 ABC

1.17 A

1.15 A

1.25 A .

.70 BCD

.60 CD

1 .07 A

1.10 A

3.15 AB

3.55 A

3.06 B

.3.30 AB

2.1 5 C

2.57 C

2 . 4 0 C

7.09 A

7.18 A

5. 7 0 BC

6.35 AB

4 . 9 0 Cl)

4. 2 0 D

4 . 0 0 0

T D W 4 / 1 0

1 1 .20 A

. 11.70 A

10.00

B

10.20

B

7.10 0

6 . 4 0 C

6

.80 C

TDW 4/22

14.56 A

13.63 All

11.30 C

12.24 BC

8.47 D

8. 3 2 I)

8 . 1 6 D to the S t u dent Newmair Kuel test. — ' ' "

2 The p lants w e r e g i v e n a pr e p l a n t i r r i g a t i o n and an a d d itional ir r i g a t i o n (75 k g / m 2 ^ 3 A c r e - i n c h ) on M a r c h 24.

3 D ry w e i g h t s e x p r e s s e d In g r a m s/plant:

TABLE 24. Total above ground dry weights of commercial lines of wheat using a high level of irrigation

En t r y

Z a r a g o z a

S i ete Cer r o s

A I M

Ca j e m e 71

A R V A N D

F l o r e n c e A u r o r e

Ram o n a 50

T D W 2/17

G r a m d r y w e i g h t at i n d i c a t e d s a m p l i n g d a t e s

T D W 2/29 T D W 3/14 T D W 3/28

.93

.70 C

.80 B

.91 A

.61 D

.46 E

.60 D

1.60 AB

1 . 8 0 A

1.60 AB

1.3 0 AB

1.62 AB

1.50 AB

1.4 0 AB

3.45 B

3.90 A

3.05 B

3.85 A

2 . 2 0 B

2. 8 0 B

2.95 B

7.7 0 AB

8 . 3 0 A

7.50 AB

7.05 B

5.56 C

5.35 C

6 . 0 0 E

T D W 4 / 1 0 T D W 4/2 2

1 1 . 9 0 A

12.20

A

10 . 4 0 B

15.86 A

15.37 A

10 . 7 0 B

12.54 B

14.27 A

7 .80 C .

10 . 4 2 C

6. 9 0 C

7.20 C

9 . 5 0 C

9. 2 5 C

1

Valu e s fo l l o w e d by the same l e t t e r w i t h i n o n e c o l u m n a r e not s i g n i f i c a n t l y d i f f e r e n t at the 0.0 5 level a c c o r d i n g

to the S t u d e n t N e w m a n Kuel test.

2 D r y w e i g h t s e x p r e s s e d in gra m s / p l a n t .

TABLE 25, Dry weights of heads and straws of commercial lines of wheat grown under normal water conditions

E n try

Z a ragoza

S iete Cerr o s

A im

Caj e m e 71 a r

V a n d

F l o r e n c e Auro r e

R amona 50

.

Hea d DW 3/14

.97 A - / 2

1.04 A

.98 A

.82 B

.76 B

.84 B

.60 C

S t r a w DW 3/14

1.23 B

2.11 A

1.22 B

1. 3 8 B

2 . 2 0 A

1.12 B

1.25 a

G r a m d ry w e i g h t s at i n dicated sa m p l i n g dates

Head DW 3/28 S t r a w DW 3/28 Head DW 4 / 1 0 S t r a w DW 4 / 1 0 Head D W 4/22

1.64 A

1.66 A

1.43 A

1.31 AB

1.02 BC

1.32 A B

.84 {

5,91 A

5.3 9 A

4.17 AB

4 . 5 9 AB

3.58 B

2.8 8 B

2.8 6 B

2.96 A

2.89 A

2.27 B

2.23 B

1.58 C

1.94 BC

1.11

D

6

. 54 A

6.41 A

4 . 6 3 B

4.97 AB

3.72 B

3.46 B

3.69 B*

5.18 A

5.1 0 A

3.86 B

3 .80 B

2.71 C

2 .92 BC

1.97 C

S t r a w DW 4/22

5.16 AB

. 5.41 A

. 3,74 A B

4.71 AB

3.39 AB

3.38 AB

3.23 B

1 V a l u e s followed by the same l e t t e r w i t h i n o ne c o l u m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0.05 level a c c o r d i n g to the S t u dent New m a n Kuel test

2

D ry w e i g h t s e x p r e s s e d in g r a m s / p l a n t .

TABLE 26. Dry weights of heads and straws of commercial lines of wheat planted at Casa Grande

Overpass Farm which received an additional irrigation on March 11

E n t r y

Z a r a g o z a

Si ete Cerros

A i m

C a j e m e 71

A It V A M O

F l o r e n c e A u r o r e

Ramo n a 50

Head DW 3/14

1.22 C * 1

1.61 A

1.28 BC

1.31 B

1.10 D

1.06 D

1.13 0

.

G r a m d ry w e i ghts at d e s i g n a t e d sa m p ling dates

S t r a w DW 3/14 Hea d OW 3/28 S t r a w DW 3/2 8 Head DW 4 / 1 0 S t r a w DW 4 / 1 0 Head 0W 4/2 2

1 .63 B CD

1 .98 A

1 .78 B

1.69 BC

1 . 5 0 D

1.68 BC

1 .54 C D

2 . 0 0 A

2.08 A

1.66

C

1.8 0 B

1 .43 D

1 .37 D

1.35 D

5 . 1 0 A

5.26 A

4 . 6 0 B

4 . 8 2 B

3.62 C

3.14 D

2.87 E

3.96 A

3.54 B

2.92 C

2.88 C

2.29 0

2.20

0

2.16 D

8.11

A

8.0 6 A

6 . 7 8 B

7.32 AB

5.11 BC

4 . 0 0 C

4.44 C

6 . 5 2 A

6 . 7 3 A

5.2 5 AB

5.32 AB

3.88 B

3.74 B

3.66 B

St r a w DW 4/22

8.4 3 A

6.35 A

6.37 A

6.94 A

5.74 A

5.32 A

5.22 A

* V a l u e s follo w e d by the same l e t t e r w i t h i n a c o l u m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0.05 level a c c o r d i n g to the S t u d e n t Newman, Kuel test.

^ D r y w e i g h t s e x p r e s s e d in g r a m s / p l a n t .

TABLE 27. Dry weight of heads and straws of commercial lines of wheat grown in Tucson and irrigated on March 24

E n t r y

Zaragoza

Si e t e C e r r o s .

A I M

C ajeme 71

.

A R V A N D

F lor e n c e A u r o r e

Ramona 50

Head DW 3/14

.92 A B * 1

1.07 A

.

1 .19 A

.77 BC

.99 AB.

.59 CD

.47 D

S t r a w D W 3/14

2 .23 AB

2.48 A

1.87 B

2.53 A

2.15 C

1.98 B

1 .93 B

Head DW 3/28

1.7 0 B

1 .93 A

1.59 BC

1.61 BC

1.3 9 C

1.41 C

1.02 D

S t r a w DW 3/28

5.40 A

5.25 A

4 . 1 2 BC

4.74 AB

3.51 BC

4 . 2 0 D

2 . 98 D

Head DW 4 / 1 0

3.05 AB

3.24 A

2.65 BC

2 . 6 6 BC

2.25 C

2.21 C

1. 6 9 D

8 . 1 5 A

8 . 4 6 A

7 . 3 5 A

7.5 5 A

4 . 8 6 B

4 . 1 9 C

5.11 B

S t r a w DW 4 / 1 0 Head DW 4/22

5.45 A

5.82 A

4 . 5 0 B

4 .78 B

3.59 C

3 . 3 0 . C '

2 .64 D

S t r a w DW 4 / 2 2

9.11 A

7 . 8 0 AB

6 . 8 0 BC

7.46 B

4.87 D

5.02 CD

5.52 CD

* V alues fo l l o w e d b y the same l e t t e r , w 1 t h i n one c o l u m n a r e not s i g n i f i c a n t l y d i f f e r e n t

at the 0 .05 level a c c o r d i n g to the s t u d e n t N e w m a n Kuel test.

^ Dry w e i g h t s e x p r e s s e d in gram s / p l a n t .

TABLE 28. Total above ground dry weights of commercial lines of wheat planted under well-

En try

Z a r agoza

Siete G erros

AI M

Ca j e m e 71

A R V A N D

Flor e n c e A u r o r e

Ramona 50

Head DW 3/14

2.01 A * 1

1.84 AB

1.52 C

1.60 B

1.38 C

1.46 C

1.25 C

S t r a w DW 3/14

1.44 B

2.07 A

1.5 3 B

2.25 A

1.52 B

1.34 B

1.70 B

G r a m d r y w e i g h t s , a t d e s i g n a t e d samp l i n g d ates

Head DW 3/28

2 . 6 0 A

2.41 AB

1.98 B CD

2.08 BC

1.82 CDE .

1.51 DE

1.30 E

S t r a w DW 3/28 - Hea d D W 4 / 1 0

5 . 1 0 A B C

5. 8 9 A

5.52 AB

4.97 ABC

3.74 C .

3,84 C

4 . 7 0 ABC

5.26 A

5.85 A

4.26 B

4.33 B

2.91 C

2.41 C

2.18 C

S t r a w DW 4 / 1 0 Head DW 4/22

6.64 A

6.34 A

6.14 A

6.37 A

4 . 8 9 8

4 . 4 9 B

5.02 B

8.9 5 A

7.0 9 B

7.39 B

7.48 B

4 . 6 8 C

4 , 5 9 C

4 . 1 5 C

St r a w DW

6.1 9 ABC

7.27 A

5.15 C

6 . 8 0 AB

5.74 BC

5.02 C

5110 C

* Valu e s f o l lowed by the same l e t t e r w i t h i n a c o l u m n are not s i g n i f i c a n t l y d i f f e r e n t at the 0.05 level a c c o r d i n g to the Stu d e n t N ewman Kuel test.

I r rigation Dates as follows: P r e p l a n t (12/12), 3/16, 3/26, 4/20, 4/24, 150 kg/m^ for p r e p l a n t and 75 k g /nr as post p l a n t irrigation.

* Dry w e i g h t s e x p r e s s e d in g r a m s / p l a n t .

TABLE 29. Leaf area indicies of commercial entries of wheat planted at Casa Grande Overpass

Farm, 1979-1980

E n t r y

Z a r a g o z a

S l ete Cer r o s

A I M

C a j e m e 71

A R V A N D

F l o r e n c e A u r o r e

Ramona 50

Minimal w a t e r t r e a t m e n t (150 k g / m ^ H o 0)

. LA 2/17 LA 3/14 LA 3/ 2 8 LA 4 / 1 0 LA 4/2 2

.579 B*

.077 AB

.629 AB

1.055 A

.504 B

.582 B

.775 AB

1.421 B

1.884 A

1. 8 1 9 A

1.803 A

.775 C

,899 C

1. 0 7 6 C

2 . 1 5 3 AB

1 .428 A

2 . 328 A 1.542 A

2 . 093 AB 1. 188 0

1.956 0

1.028 B

1.534 C

1. 399 C

1.432 C

.926 BC

.87.1 BC

.660 C

.892 A

.825 A

.751 A

.720 A

.50 BC

.66

B

.37 C

3/24 I r r igation t r e a t m e n t *(225 kq / m ^ H o 0)

LA 2/17 LA .3/14 LA 3/28 LA 4 / 1 0

.979 AB

1.033 A

.488 C

1.004 A

.821 AB

.555 C

.778 B

1.547 B

,2.029 A

1.945 A

2 .139 A

.963 C

.974 C

1.138 C

2.291 A

2 . 365 A

2 . 1 3 9 A

2. 1 5 4 A

1.485 B

1.555 0

1 . 456 B

1 . 605 B

1 . 6 3 0 A

1.613 A

1 . 356 B

1.131 BCD

1.027 D

>972 0

LA 4/22

1.081 A

1.023 A

.968 C

.875 C

.705 D

.566 D

.537 0

Entry

Za r a g o z a

Si etc C erros

AIM, ,

C a j e m e 71

A R V A N D

F l o r e n c e A u r o r e

R a mona 50

3/11 I r r i g a t i o n t r e a t m e n t (225 k g / m lUO)

LA 2/17 LA 3/14 LA 3/28 L A 4/1 0

L A 4/22

.969 A*

.969 AB

.717 BC

.942 AB

.598 C

.601 C

1 . 9 5 9 B

1.367 A

1.921 A

2.021 A

.821 D

.934 D

. .791 ABC 1.098 C

2.422 A

2. 3 9 5 A

2 . 244 A

2, 206 A

1.767 B 1. 249 DE

1.927 AB 1 . 203 E

1 .582 B

1. 7 6 5 BC

1 . 1 6 3 B

1 . 696 A

1.125 A

1. 6 7 0 AB , 1 . 072 AB

1.407 CD .897 B

.659 C

.956 F

.565 CO

.444 0

LA 2/17

.977 A

.811 AB

.801 AO

.971 A

.754 B

.750 0

.766 B

Wei 1 i r rigated t r e a t m e n t (525 k g / m I12 0)

LA 3/14 LA 3/28 LA 4 / 1 0 LA 4/22

1.964 A

2. 040 A

1.910 A

2.123 A

2.562 A

2 . 5 1 3 A

1. 663 B

1.873 A

1.695 AB ' 1. 789 B 1. 356 0

1.803 AB 2 . 2 9 3 AB 1.422 D

1.448 B 1.878 B 1.411 0

1.31 BC

1.272 A

2.551 A 1.787 AB 1.194 AB

2.271 AB 1.614 C 1.011 CD

.900 D

.937 CD

.941 CD

* Val u e s f o l l o w e d by the same l e t t e r w i t h i n a c o l u m n are n o t s i g n i f i c a n t l y d i f f e r e n t at the 0 . 0 5 level a c c o r d i n g to the Stu d e n t N e w m a n Kuel test.

82

24). Cry weights of entries of the well-watered treatments, which

received the first irrigation on March 6 were greater than all the

treatments from March 28 onward (Table 24 vs. Tables 21, 22 and 23).

Large dry weight differences were found among entries grown on

a given irrigation regime. Prior to the March 28 sampling, which just

preceded anthesis in most entries, there was little or no correlation

of dry weight to yield. From the March 28 sampling, highly

significant correlations were found between plant dry weights and

yield within each irrigation treatment (Tables 17 though 20), except

in the April 22 harvest from treatment receiving irrigation 3 weeks

prior to anthesis.

Separation of total weights into head and straw components

showed that head weights continued to increase from the first to last

sampling in all irrigation treatments (Tables 25 to 28). Straw

weights on the other hand, increased until the April 4 harvest and

later dropped in the ’dryland’ study. In treatments which received one

or more irrigation, straw dry weight dropped in some but not all

entries and thus may be related to the fact that irrigation delays -

development. Regardless of the irrigation regime, highly significant

correlations were found between head weights and. yield of all sampling

periods (Tables 17 through 20). On and after the March 28 sampling,

significant to highly significant correlations were usually found with

straw weights and yield for 3 of the 4 treatments. Plants which

received water 3 weeks before flowering (Table 18) showed.no relation

of straw weight to yield,

83

Examination ..of leaf area indices (Table 29) showed that .

Zaragoza and Ramona usually had the highest and lowest LAI from

anthesis onward in all treatments. Furthermore, additional irrigation

helped delay leaf senescence and kept leaves green for a longer period

of time. For instance, in plants which received an additional

*

' irrigation (Table 29). Additionally, high correlations were found stonger in treatments which received less water than the control

(Tables .1? to 20).

84

Water Relations and. Leaf Growth Studies

Tucson Casa Grande Overpass Farm (1979-1980)

Crop performance and yield are the result of gene expression

as modified by continuous interaction with the environment (28). This

is well established by examining results obtained with dwarf and

semi-dwarf spring wheats. The advent of short-stalk varieties led to

striking increases in productivity in moist or irrigated regions (19);

however, yield increases of plants grown under dryland conditions

usually were not dramatic..

Since water often Is a limiting factor in crop production throughout the world, a better understanding of long term effects of stress on growth and yield should aid in selecting plants for efficient water use'. The present knowledge of such relationships is highly empirical and has been obtained from many irrigated trials performed over many decades (49). These are, however, general ideas about.plants responding physiologically to stress (29), and part of the experiment at the Casa Grande Overpass Farm was aimed at utilizing this knowledge to see how soil and plant water relations might be

/

related to productivity. .

Soil and plant'water status measurements were taken once or

twice a week just after sunrise for plants grown under 'dryland' and

values for soil water potential ('fs), tissue water potential (¥1),

tissue osmotic potential (?) and turgor (p) for all entries grown

under ’dryland’, and .'well-watered' conditions, respectively.

»

TAB Tissue water potential (^), osmotic potential (1T) and turgor pressure (p) of seven wheat varieties grown under 'dryland' conditions at the Casa Grande

Overpass I arm, 1980 f u l l y

/ a r a i | n / a

’ l o l o 1 o r r o 4

M M r . O j l ' k C 11

.•llVAI.lt

f. n r m p

IV m .vt f ill

1 / 6

• i> ♦

/ n

• P

S . 6 14 6

; o 14 1

U.S.

1 4 . 1

. 1 0 14 6

O S

16 1 i i i i

7 4

7 m

6 . 6

6 9

9 0 16 7 7 7 o n 1 7 . 1

9 7 I I . II

7 . 1

7 6

11 6

14 9 6 . 3

1 1 4 19 .1

S . 7

1 / 1 0

■ P

H O

1 0. 1 111 1

10 6 17 II

I I I 0 1 1 1 n o 17 7

14 S 1 9 . S

7 7

7 1

6 7

S 0

3 / I S

. l> n o i n 9

I I . 0 I B 0 n o i n s

I I 4 17 9

1 7 . 0 71 2

7 9

7 . 1

7 5

6 . 5

4 7

0 .7

17 7

14 4 S . 2

1

4 9 i n n I S 7 4 . 4

I S . 7

19 7

4 0

1 2 . 2 1 6 . 1 1 . 9

1 6 . 7 19 7

3 . 0

17.11

16 . 1 3 . 5

3 / I B

♦ i>

5 . 4

1 3 . 4

9 7 16 7 n n 16 n

H O

7 . 5 n o

7 4 14 2

9 0 16 0

6 0

7 0

1 1 6 16 9 5 3

17 0

19 11

2 H 1 1 . 4 I I I . 4 5 . 0

S o il l l a l o r r n l n . i l 1 ' 1

4 . 3 m 4

9 . 5

10 7 4 .4

3 / 7 1

♦ ’

5 . 0 11 0

7 . 6 1 5 . 7

6 6 14 6

6 0 1 1 0

H O

I S O i> n o

7 6 n o

7 0

7 0 n o

14 1

5 . 3

1 7 . 0 1 7 . 0 5 0

3 . 0

1 / 7 7 t

0 6 17 6

9 . 7 16 6

9 5 I 7 . J

I I I 0 1 6 . 5

1 1 4

16 1

11

II 0

7 4

7 0

6 5

5 0

4 / 5 4 / 7

+ "

P

1 1 . 7 19 1

17 0

1 9 . 1 n o

1

I.H

i n n

7 0 6

16 7 7 0 . 5

7 . 9

7 . 1

7 8

6 8

4 . 1

"

*

1 4 . 0 71 7

14 n 21 II

11 4 7 0 . 7

16 2 7 2 7

21 7 24 2

. . . .

4 / 1 2

V

P

7 7 15 6 7 3 . 0

7 . 0 16 6 7 1 . 5

7 4

5 . 9

7 1 16 7 2 1 7

6 . 5

1 0

7 . 5 i n 1

7 4 . 9

6 . 6

7 7 6 7 5 . 0 2 . 4

4 / 1 4

P

1 1 . 7 1 9 . 5

1 1 2 7 0 . 4

7 8

7 . 7

1 2 . 4 7 0 . .1

7 . 9

1 6 . 7

2 1 . 4 7 0

2 1 . 0 7 5 0 4 0

17 6

1 6 .B

16 6 1 9 . 6

4 7

14 6 1 7 . 7

1 9 2 5 0 2 6 1

I I 711 0 7B 6

3 . 1 1 9 . 7 71 1

10

i n o 7 0 6 2 . 6 2 3 . 4 2 4 6 1 . 2 7 0 7 7 9 . 7

1.0

1 7 . 0 1 4 . 0 7

4

5 4 0 0 1 7 * 4

1 1 . 4

' . n i l was w a t p w l on I ? / I 2 an.I i#n p lv m l r a i n f a l l o f I I on 1 / l f i , 4 k ti/w on 1 / ^ 0 , a in l I . ?S k«|/f« ' " 4 /1 1 .

00

c n

IABLL 31. Tissue water potential ( i

| ) , osmotic potential ( tt

) and turgor pressure (p) of f r r r o \

AI M

r * j r w ; i

i f v a i a i

1

seven wheat varieties grown under well-watered conditions at the Casa Grande

Overpass Farm, 1980

1/6

i / m

1/10

1 / I S i / i a 1/ 71

*

.

• P

4

P

9

" '

P

♦ ■

P

P

P

1/ 37

P ♦

4 / S i> ♦

4 / 7

. 1

' 4

4 / 1 7 p *

4/ 14

S 7 14 7 9 0

S t l i t H 0

6

4

14 6

0 7 t 0 1 1. 9

9 . 0

7 . 9 a i n o I S n . s I S U S

4 . 0 I S O

10 7

7 4 I t 4 a s t 4 I S . t 4 . 7

4 0 17 5 a s S 7 14 9 s . a M S

1.1

1 . 0 m o 1 0

7 0 14 0 n . 4

10

i s o t t

I S M S

1.0

1.0

14 0

10

n . 4 I S O t t

9 0 I S O

6

I t 11 4

6

6

1. 7 1 1 1 t s M S

111

a

I S

/ . s m s ; . o

s o i s 0

0

o

7 . 0 1 4 . 0 7 0 4 1 M l 10 7

7 . 1 1 4. 1

*

10

S . 7 I S O

9 0

1.0

S 3

M S

1 4 . 9

0 t o

111

1.1

S O

6

1

10 s

9 7

4. 1

S O

M S

I S 0

10 4

10

a o s o

11

0 . 7

0

t 0 I S 0

6

1

11

9 0 a o

7 . 5

6

0

a 4 I t 6

I S

7. 7 t 6 I S 1 m s t o

9 0 I t 1 t S I S

I S 1 a i

14 7

1 7

6 s

M . s n o t 7 M 7

6

i n M 4 t t

10 6

9 t i t 4 t n

.

1.0

1 3. 7 t 7 7. 6 l i t t o

0

1

S O

n

0

1 i « 1

s n

4

o m s s s

11

6

t a

1 . 0 I J . o

t n 9 0 I S O t o I I 0 I I 1 t i t 9 11

4 t S a I 14 7

6.0 10.1

I S 1

S O 17

4

I t 4

4

0

10

t o 9 . 0 I t 0 7 . 0 a t I S 6 7 0 1 1 . 7 I t 7 s o I S O 19 0 4

0

1 1 4 i n 6 S . 7

S. 1 I S 1 t 5 I S S t o I S 1

1.0

i s o n o

9.7

i t 7 1 0

10

17 0 t o

S o i l Wel er

' o l e n t l e l

7 0

1.0

1.1

10

.5

1

.1

7 6 1 . 5

•7

So 1 1 1 w » re t M l o r r f on 7 / 7 9 , 1 / I t , l / ? t 4 / 1 0 a n il 4 / 7 4 I I f M l a l i o r f i f l v n d r a l n l a l l

nl

I I no 1 / 1 6 , 4 k o / m ^ on 1 / 7 0 , 4 ik I I 7S ko/«* on 4 / 1 1 o o

Os

87

Variations in Y s were largely due to changes occurring

following rainfall. The Casa Grande Farm received about

38 kg/m2

rainfall in January and 70 kg/m2 in February. On the first sampling

on March 6, vs of the dryland border was less than -4 bars and in a 4

day interval, vs dropped quite rapidly to about -10 bars (Table 30).

Vs were raised when 11.0 kg/m2 and 4 kg/m? rainfall occurred on

March 15 and 19, respectively. The Vs decline after March 21 occurred

less rapidly than after March 6 but it is not clear if these

differences are due to sampling error or to change in distribution of

roots or other factors.

largely reflects changes in Vs (Figs.. 14 and 15). In all cases, vi

values were lower then VS but wide differences in Vl were obtained

among entries. Vl for the higher yielding Zaragoza, Siete Cerros,

Aim, and Cajeme were numerically greater than those of the lower

yielding Florence Aurore, Ramona and Arvand, throughout the sampling

period. Additionally, VI for Ramona and Florence Aurore dropped

precipitously after April 5.

Comparison of vl, v, and p for the highest and lowest yielding

entry provided further insight on how plants responded to water

deficits. In the case of the highest yielding Zaragoza (Fig. 16) v

.and

Vl

closely paralleled each other throughout the growing season so

that turgor values were maintained at a constant 8 bars. On the other

hand, Ramona had lower Vl,v and also p throughout most of the growing

season and turgor began to decline below about 3 bars from March 2?

(Fig. 17). The low p of Ramona may be related to low yield values ■

Rain

-8 f loro nee Aurora

GO

-16

_

20

._

-3Zj

3 /6

3/10

3/15

3/21 3 /2 7 4 /5

4/15

CALENDAR DATE

FIG. 14 Soil and plant water potentials of entries grown under

'dryland' conditions at the Casa Grande Overpass Farm during the

1979-1980 growing- season.

o o

00

-4

CL

12

A n a n d

Rain

3/0

3/10

3/15

4/6

CALENDAR DATE

FIG. 15 Soil and plant water potentials of entries grown under

'dryland' conditions at the Casa Grande Overpass Farm during the

1979-1980 growing season.

00

ZARGOZA

- 4

8

.

10

.

12

-14

.16

-18

.20

3 /6

3 /2 7

4 / 5

CALENDAR DATE

FIG. 16 Relationship of leaf water potential (ij/l), osmotic potential

( i t

)

, and turgor pressure (p) at specified dates for Zaragoza plants grown under 'dryland1 conditions at the

Casa Grande Overpass Farm during the 1979-1980 growing season

RAMONA

-T8

, 3 0

- 3 2

4 /2 7

CALENDAR DATE

FIG. 17 Relationship of leaf water p o t e n t i a l (^1), osmotic potential (ir) and turgor pressure (p) at specified dates for

Ramona plants grown under 'dryland1 conditions at the Casa

Grande Overpass Farm during the 1979-1980 growing season.

92

that are obtained in this entry., but the exact reason for this is

still unclear. Conceivably, low turgor may mean that the potential

for cell growth is reduced, but this must be explored further.

In the well-watered border (Table 31), as expected V s was

considerably higher than that in the dryland treatment (Table 30) but

¥ s often were less than -3 bars, probably because the soil had

relatively low water holding capacity.

Graphical comparisons of ¥1 with ¥ s showed that patterns of

fluctuations in ¥l for different entries were alike, and in most respects resembled changes in ¥ g (Fig. 18). ¥1 were in all cases

lower than ¥s, but entries varied widely in ^1. The lowest yielding

Ramona again had the lowest ^1, also ^1 for the next lowest yielders -

Florence Aurore and Arvand were less than the other four entries. As treatment (Figs. 15 and 16).

Comparison of ^1, 17 and p showed that values for Zaragoza

(Fig. 19) were in all cases higher than those of Ramona (Fig. 20), and

respective entries under dryland conditions (Figs. 16 and 17). These

results are compatible with current thinking that under drought

conditions', plants reduce T.(by increasing solute accumulation) so .

that water entry may continue. The nature of omotio agent involved

in 'oaaotic adjustment’ was not determined, but proline and a number

of other organic compounds have been suggested (30, 5.3) • The exact

reason Why yields of Zaragoza are greater than Ramona, are unknown, but

there may be relationships between yield and osmotic adjustment, and

•6 —

JO-

.

12

.

.

14

.

.

4 .

.

6

-

.8

Zartoza

Ramona

Siete Cerroi

-4

-

.

10

.

iim

Ca/eme

laia

3 /8

3/10

3 /1 5 3 /M

3/27

V 5

CALENDAR DATE

FIG. 18 Soil and plant water potentials of different entries grown using recommended irrigation at the Casa

Grande Farm d u ring 1979-1980 growing season.

93

ZARGOZA

(Z) oc

CO - 4

o

Q_

(£ r

<

<

16

oa

3 / 6

3 /1 0 3 /2 1

3 /2 7

4 /5 4/14

CALENDAR DATE

FIG. 19 Relationship of leaf water potential (i|zl), osmotic potential ( tt

) and turgor pressure (p) at specified dates for

Zaragoza grown under 'well irrigated' conditions at the Casa

Grande Overpass Farm during the 1979-1980 growing season.

RAMONA g '*

z - 1 0

£

0 - 12

01 g "

I '« u_

- 18 a

_ i

<

CD ir

o

o

oc

?

3 / 6 3 / 1 0

3 / 1 5 3 /2 1

4 /5 4/14

CALENDAR DATE

FIG. 20 Relationship of leaf water potential (ij^l), osmotic potential

( t t

)

and turgor pressure (p) at specified dates for

Ramona plants grown under 'well irrigated' conditions at the

Casa Grande Overpass Farm during the 1979-1980 growing season

UD

U1

96

also root growth. Under well watered conditions, solute

concentrations contributing to irare less in Zaragoza than in Ramona;

when stressed, both Zaragoza and Ramona increase their solute levels,

but the final levels in Zaragoza are less than in Ramona. If

maintenance of solute levels require energy, the requirements needed

by Zaragoza are clearly less than in Ramona.

Additionally, root distribution patterns of different entries

under dryland and well watered conditions may, play an important role

in plant water status. Preliminary studies of these entries has shown

irrigated conditions than Zaragoza. In addition, root length and

lateral expansions were lower in all entries under irrigated

conditions (3)• A more detailed study of root habits is certainly

promising.

Leaf Expansion Growth

From the view point of productivity, expansive growth is very

important, since it is the means of developing, leaf area for interception of light as well as carrying out photosynthesis. (11).

. -

Leaf enlargement is the most sensitive physiological process affected

by water stress (7, 8, 29, 30). The demonstration of strong

relationship between water stress and leaf growth in several

laboratory studies (7, 8, 11, 19), led to the belief that measurement

of leaf expansion in the field probably could help sense the degree of

stress long before wilting can be detected or physiological processes

such as photosynthesis, translocation, and partitioning of assimilates

97

would be damaged. To test this belief, the growth of young flag

leaves on tillers were measured about one to two weeks prior to

anthesis.

Data from preliminary studies (April 5) showed that the full

length of leaves under dryland conditions were less than under well

watered treatment. Under dryland conditions, leaves for most entries

generally reached 9-11 cm, but lengths for Florence Aurore, and Ramona

were less. The reduced growth in the latter 2 entries may be related

to.the fact that leaves from these plants decrease in ¥1 dramatically

after April 5 (Fig. 14). Final length of well watered plants ranged

fron 13 to 23 cm. Data from Table 32 can be used for calculating

.. growth rates and it is evident that calculated rates depend on the

length at the initial sampling period. In the case of the Zaragoza,

leaves appeared to complete growth by March 18, but leaves selected

for Siete Cerros were.only 2 cm long and grew to about the same final

length as Zaragoza. This shows that if attempts are made to measure

immediate effects of stress on length, it is important to begin

studying uniform long leaves which are far from fully expanded.

TABLE 32. The expansion of flag leaves on tillers of wheat plants

Leaf l.en<|lh on Individual dat e amd E x p a n s i o n duriiu) lime Inlerva 1 und e r D r y l a n d treatment

Ent r y

Zaragoza

Sietc Cerros

A I M

C a j e m e

A r v a n d

F l o r e n c e A u r o r e

Ramona

M a r c h Ifl

M a r c h 21 initial length (cm) e x p a n s i o n (cm) length (cm) e x p a n s i o n (cm)

10.5

2 .0

4.3

7.2

6.6

2.8

6 . 0

7.0

3.3

0 . 9

1.1

2. 0

0 . 6

10.5

9. 0

7.6

8.1

10.5

4.8

6.6

9

1.0

0 . 5

0 . 3

0 .6

0 . 9

9

M a r c h 27 Apr i1 !

length (cm) e x p a n s i o n (cm) length (

10.5

10.0

8.1

8.4

11.1

5.7

6.6

1.0

9

0.1

0 . 5

0.1

9

9

10.6

10.0

8.5

8. 9

11.2

5.7

6.6

E n t r y

Z aragoza

Slete Cerros

A I M

C aje m e

A r v a n d

F l o r e n c e A u r o r e

Ram o n a

Leaf length on Individual d a t e an d E x p a n s i o n d u r i n g time interval under I r rigation ( c o n t r o l ) Treatment

M a r c h 18

Initial length (cm)

7.5

1.2

13.4

12.8

15.1

9.6

11.5

e x p a n s i o n (cm)

10.5

3.5

0.1

4.4

6 .3

7.6

1.5

M a r c h 21 length (cm)

18.0

15.5

13.5

17.2

21.4

17.2

13.0

e x p a n s i o n (cm)

4.1

0. 2

0 .5

5 . 0

0.6

0 . 5

9

M a r c h 27 length (cm) e x p a n s i o n (cm)

22.1

15.7

14.0

22.2

22. 0

17.7

1.3.0

9

9

9

9

9

9

9

Apr 11 !

length I

22.1

15.7

14.0

22.2

2 2. 0

17.7

13.0

99

Summary and Conclusions

A number of commercial and experimental lines of spring wheat

were grown as a winter crop in Mesa and in Tucson, Arizona. Low

■density seedling rates (15 to 20 kg/ha) were used and in most

treatments, plants received a pre-plant irrigation of 150 mm plus

supplemental water only as rainfall (dry land treatments). In Tucson,

additional experiments were performed in which measured amounts of

water were added at specified periods. During the latter half of the

growing season, representative plants were harvested at approximately

weekly intervals to determine if correlations existed between

physiological and developmental traits and final grain yield.

Plants were grown in Mesa on a clay loam soil in 1978-1979,

and also in 1979-1980 and the rainfall in the two years was 150 and

153 mm, respectively. Yields in Mesa ranged from 2400 to 3400 kg/ha

in 1979, and 2400 to 3700 kg/ha in 1980. In Tucson, plants were grown

on a sandy loam soil in 1979-1980. When grown under dryland

conditions, total rainfall during the growng season was 134 mm, and

yields ranged fron 1100 to 3000 kg/ha. Yields were increased to 2300

to 3600 kg/ha when additional 75 mm water was applied on March 11, (2

to 3 weeks prior to flowering)., and 1600 to 3400 kg/ha when the 75 mm

water was applied on March 24 (1 week before flowering). Plants which

received the recommended levels of water (525 mm total) yielded 2700

to 4500 kg/ha. Some of the lines of wheat were common to all .

experiments, and their yield rankings were maintained regardless of

100

the locality of growth, the year in which crops were grown, or the

amount of water which was applied, date , tiller number or spikelets/spike in each of the dry land .

studies. Significant to highly significant correlations usually were

obtained between yield and many other yield components. Values of r -

(listed in order of Mesa, 1978-1979; Mesa, 1979-1980; and Tucson,

1979-1980) between yield and (a) grain number/unit area were (0,34;

0.60; 0.75), (b) grain number/spike were (0.65; 0,60; 0.60), (c) grain

weight/spike were (0.93, 0,96; 0.97) and (d) grain weight/1000 seeds

were (0,93; 0.96; and 0,99). These data show that under dryland

conditions different lines of wheat tended to produce the same number

Significant correlations were found between grain numbers/unit area or per spike, but factors which contributed to grain weight were of primary importance in determining yield.

In an effort to clarify the relation of grain.to head

development, the weights of individual grains on each spikelet were

plotted as a function of spikelet number. These comparisons showed

low yielders produce 3 grains/spikelet (b) the grains in the central

regions of spike from high yielding wheats tended to be larger than

those from low yielding cultivars.

Significant differences were found in total plant dry weight

among entries, and from anthesis onward, dry weight values and yields

closely paralleled each other, Despite these correlations, ability to

101

grow well vegetatively was not considered a.general indicator of yield

potential, This is suggested partly because dry weights of entries

sampled during the early vegetative growth were not highly correlated

with yield, In addition, straw weights at anthesis were not usually

related to yield.

In contrast to the straw weight data, head weights correlated

very strongly with yield differences i Although other explanations may

exist, this suggests that the potential for grain production already

is determined by flowering. Further investigations of the development

and anatomy of heads slightly before and after anthesis should provide

a basis for explaining why.grain weights should be related to yield, :

Examination of leaf area data showed that in all experiments,

LAX usually peaked just prior to antheSis. Correlation coefficients

values between yield and LAI changed from non-significant at early

vegetative stages to highly significant when samples were harvested at

and after anthesis. This suggests that photosynthesis occurring

during head development is of critical importance and physiological

and anatomical studies of both vegeative and fruiting structures .

should be conducted during head development rather than at earlier

stages, ;

In addition to increasing yields, irrigation treatments tended

to increase tiller number's, delay anthesis, and in some instances,

components. When a single irrigation was used, the time of water

application not only affected yield but the pattern of head

development. Irrigation during grain filling (March 24) mainly tended

102

to increase grain weight/spike and grain numbers/unit area, and

correlation values between yield and yield components were similar to

those of entries from the ’dryland’ treatments, Ho significant

correlations existed between yield and tiller numbers, but correlation

of yield with grain numbers/unit area (r = 0.72) were significant.

Very different relationships of yield to yield components were

found in plants that were irrigated 3 weeks prior to flowering (March

optimal water, tiller numbers were not correlated with yield;

nonetheless, grain number/unit area (r = 0.98) or grain number/spike -

(r = 0.94) were more closely correlated to yield than grain

When water was added throughout the season, grain yields were

of grains/unit area, and number of tillers/unit area. Highly

significant correlations were obtained between yield and tiller

correlation was found between yield and grain weight/1000 seeds.

.Examination■of heads of plants grown under irrigated

conditions showed similar relations of grain to head development as. in -

the dryland treatments. High yielding cultivars tended to produce

more grains/spikelet than the low yielding ones. In addition, central

regions of spike from- high yielding wheats tended to be larger than

those of low yielding cultivars.

103

As in plants grown under dryland conditions, yields of all

irrigated plants were not correlated to dry weight or to LAI during

early stages of development. From approximately anthesis and

thereafter, however, highly significant correlations were found

between plant dry weights and yield in all sampling periods.

Significant correlations were also found between yield and LAI of the

well watered plants; and LAI values of the single irrigation

treatments were correlated highly significantly with yield. All

irrigation treatments tended to delay senescence.

Leaf water potentials measured 1 to 2 weeks prior to anthesis

were higher in well-watered than in the dryland treament. In

addition, high yielding cultivars had higher water potentials than, low

yielding cultivars in both treatments. Osmotic adjustment occurred in

both well-watered and dryland entries, but to a lesser extent in low

yielding cultivars as well as all entries in the well-watered

'treatment.

The results from the two year study at Mesa and the one year

study at Tucson show that a number of criteria can be used to aid in

selecting plants which will yield well when grown under dryland

conditions in Arizona. Tiller numbers appeared to be constant

regardless of the type of wheat grown. Plants which yield well should

be those that have high head dry weights per plant, and high grain

weights/1000 seeds. Other measures such as LAI and plant dry weights

can be used in measurements made at anthesis and thereafter.

Yield comparisons made between dryland and irrigated fields

showed that if a single'irrigation is to be used, the most critical

period for water application appears to be 2 to 3 weeks prior to

anthesis. This is in agreement with findings of Fischer (20). In the

low yielding Ramona, yields were more than doubled by the application r

-

of 75 mm water at that time. Water application at the time resulted

in higher yields in all entries than when water was applied about 1

week prior to anthesis. At approximately 2 weeks prior to flowering,

water potential values of plants grown under dryland condition were

clearly less than that of the well watered plants. Further studies of

the relationship existing between leaf water status and head and grain

development from approximately this 'critical time' (2 to 3 weeks

prior to anthisis) will clarify why yield reductions can occur during

stress. These studies may aid in setting guidlines for irrigation

scheduling.

105

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