Upload
others
View
11
Download
0
Embed Size (px)
Citation preview
MORPHOLOGICAL CHARACTERISTICS AND YIELD OF
GRAIN SORGHUM (Sorghum bicolor L. Moench)
by
JOHN C. BICKEL, B.S.
A THESIS
IN
CROP SCIENCE
Submitted to the Graduate Faculty of Texas Tech University in
Partial Fulfillment of the Requirements for
the degree of
MASTER OF SCIENCE
Approved
Accepted
August, 1983
/ -I
r;i',h , " ACKNOWLEDGMENTS
The author wishes to thank the chairman of the committee. Dr. Kent
R. Keim, for his many helpful suggestions and patience during the
preparation of this manuscript. The aid of the members of the
committee. Dr. R. C. Jackson and Dr. D. R. Krieg, is appreciated as
well. For their help during the collection of the data, thanks go to
Pam Nafzger and Michelle Fritz. The patience and understanding of my
wife, Connie, is deeply appreciated. Many thanks are given to my
father and mother. Bill and Priscilla Bickel, who have supported me at
all times in many ways. Thanks are extended to the typist, Jan Readio.
Acknowledgement is also given to the Dryland Crop Improvement Grant,
without which this work and thesis would not have been possible.
11
TABLE OF CONTENTS
ACKNOWLEDGMENTS ii
LIST OF TABLES v
I. INTRODUCTION 1
II. REVIEW OF LITERATURE 3
Physiological Features 3
Leaf Area and Yield 4
Panicle and Yield 6
Stalk and Yield 7
Number of Leaves 8
Height of Plant 8
Morphological Trait Correlations with Grain Yield 9
III. MATERIALS AND METHODS 12
Germplasm 12
Field Layout 12
Characters Investigated 13
Statistical Analysis 14
IV. RESULTS AND DISCUSSION 16
Morphological Characteristics 16
Dry Weights 19
Grain Yield and Related Traits 23
Morphological Trait Means 25
Dry Weight Means 33
Mean of Grain Yield and Related Traits 34
111
Correlations Between Morphological Traits, Dry
Weights, and Grain Yield 35
V. SUMMARY AND CONCLUSIONS 48
APPENDIX 51
REFERENCES CITED 53
IV
LIST OF TABLES
1. Analysis of variance (mean squares) of data on morphological traits of inbred lines grown under preplant plus one (PP +1) and preplant plus three (PP +3) irrigation levels (1980) 17
2. Analysis of variance (mean squares) of data on morphological traits of inbred lines over water levels (1980). . . . 18
3. Analysis of variance (mean squares) of data on plant dry weights for inbred lines grown under preplant plus one (PP +1) and preplant plus three (PP +3) irrigation levels (1980) 20
4. Analysis of variance (mean squares) on data for plant dry weights over water levels (1980) 21
5. Analysis of variance (mean squares) of data on plot grain yield and related traits for inbred lines grown under preplant plus one (PP +1) and preplant plus three (PP +3) irrigation levels (1980) 22
6. Analysis of variance (mean squares) on data for field plots over water levels (1980) 24
7. Means of morphological traits for inbred lines grown under preplant plus one (PP +1) and preplant plus three (PP + 3) irrigation levels and over water levels (1980) 26
8. Means of plant dry weights and plot grain yield for inbred lines grown under preplant plus one (PP +1) and preplant plus three (PP +3) irrigation levels and over water levels (1980) 31
9- Correlations of morphological traits and dry weights on morphological traits and dry weights for inbred lines grown under preplant plus one (PP +1) and preplant plus three (PP + 3) irrigation levels (1980) 36
10. Correlations of morphological traits and dry weights on morphological traits and dry weights for inbred lines over water levels (1980) 37
11. Correlations of grain yield and related traits on morphological traits and dry weights of inbred lines grown under preplant plus one (PP +1) and preplant plus three (PP + 3) irrigation levels (1980) 39
V
12. Correlations of grain yield and related traits on morphological traits and dry weights of inbred lines over water levels (1980) ^0
13. Correlations between grain yield and related traits for inbred lines grown under preplant plus one (PP + l)i preplant plus three (PP +3) irrigation levels and over water levels (1980) 47
VI
CHAPTER I
INTRODUCTION
Grain sorghum (Sorghum bicolor L. Moench) is an important crop in
the United States, particularly in the semiarid region of the
Southwest. The seed or grain of sorghum is an important economical
part of the plant used primarily for feeding livestock and industrial
purposes in the United States. Grain sorghum is important for human
consumption in parts of China, India and Africa.
Texas grain sorghum acreage has decreased yearly from a high of 3
million hectares harvested in 1975 to a present estimated level of 1.5
million hectares. During the same period, on the semiarid Rolling
Plains region, the sorghum area decreased 66%. Average yield in the
period 1975 to 1980 ranged from 995 kg/ha to 2386 kg/ha (Clark and
Pietsch, 1980).
Grain yield of sorghum is related to previous environmental in
fluences during the growing season and effect of such influences on
various physiologic systems during development. Water and temperature
are the major factors influencing yield in the Rolling Plains region
and are largely responsible for the wide variations in grain yield.
Effects such as those caused by water stress are manifest through
influences on various morphologic characteristics of the developing
sorghum plant. An understanding of these effects could provide
information useful in developing desirable types in a sorghum genetics
and breeding program.
Previous studies with wheat indicate a potential for use of
various morphological traits at various growth stages (especially
anthesis) and their association with grain yield as a selection tool
in a breeding program. However, little information exists for sorghum
concerning the relationship of grain yield with morphologic traits
during development.
The main objective of this study was to determine if biologically
important relationships exist between grain yield and various
morphologic characters for eight sorghum genotypes grown under two
water levels. If genotype by water level interactions occur, then
hybridization and extraction of segregates suited to environmental
conditions will be possible.
CHAPTER II
REVIEW OF LITERATURE
Physiological Features
Blum (1974) evaluated sorghum cultivars and found low initial
water use prior to anthesis relative to the total used at maturity to
be a positive drought response. Of two sorghum genotypes grown under
water stress in the field, Stout, Kannangara and Simpson (1978)
observed one genotype to be capable of responding by shortening
developmental sequences, thus taking advantage of early season
moisture. When compared to the irrigated treatment, this genotype was
found to be in a later stage of inflorescence development.
According to Acevedo, Hsiao and Henderson (1971), water uptake
provides impetus for cell enlargement. Water use efficiency is the
ratio of dry matter produced to water used. Under conditions of
limited moisture, there is an optimal level of vegetative growth,
depending on the available water supply, for maximum grain yield
(Fisher and Kohn, 1966b).
Fisher and Kohn (1966b), working with wheat, found large
differences in vegetative growth caused relatively small differences
in evapotranspiration rates when soil moisture was adequate. An
increase in total dry matter of lOOg/m^ was associated with an
increase in cumulative evapotranspiration of 1.27 cm.
Sorghum has been shown to use water more efficiently for grain
production than some other grain crops (Major and Haman, 1981;
Sanchez-Diaz and Kramer, 1971; El-Sharkaway and Hesketh, 1964). Major
3
and Haman (1981) found that sorghum used water more efficiently than
barley (Hordeum vulgare L. 'Gait') or wheat (Triticum aestivum L.
'Neepawa'). Kernel growth ceased after whole-plant growth ceased for
barley and wheat, but for sorghum there was continued kernel growth.
Sanchez-Diaz and Kramer (1971) compared corn (Zea mays L.) and sorghum
water deficits on leaf segment samples. The greatest deficit of
sorghum was only 29% at a leaf potential of -15.7 bars while corn was
56.6% at -12.8 bars. This indicated that sorghum retained a larger
fraction of its water at given water potentials. El-Sharkaway and
Hesketh (1964) used temperature and water stress as treatments to
compare young fully expanded leaves of sorghum (Sorghum vulgare L.
'Hegari'), cotton (Gossypium hirsutumL.), sunflower (Helianthus annus
L.), and soland (Thespesia populnea L.). Sorghum did not cease
maximum photosynthesis until the leaves were curled. Other species
used were visibly wilted before photosynthesis was depressed by water
deficit.
Leaf Area and Yield
Agricultural crop yield is usually measured in terms of weight of
crop per unit of land area, and is an integration of effects of
various factors on many physiological processes and morphological
components (Moss and Musgrave, 1971; Watson, 1942).
McKree and Davis (1974) applied five cycles of soil water deficit
to sorghum under hot dry field conditions. Declines in leaf area were
found to be due to decreased leaf cell numbers and decreased cell
size. Decreases in leaf area due to stress were primarily the result
of decreased cell division.
Several studies indicate leaf area to be a major determinant of
crop yield. From four field experiments in 1961 and 1962, Elk, Kalyu
and Hanway (1966) found that grain yield of corn was linearly related
to leaf area index (LAI) days. Grain yields were most closely related
to LAI measurements closest to day of first silking. In a study of
twelve sorghum genotypes, Leeton (1978) observed total leaf area to be
highly correlated with yield.
Leeton (1978), working with sorghum, took leaf area measurements
at several stages of plant development from panicle initiation through
bloom plus 30 days. She found total leaf area at bloom to be highly
correlated with yield, but negatively correlated with photosynthetic
rate. This negative correlation was explained as the result of sink
size being a function of total leaf area. Excess leaf area existed in
relation to sink strength, and photosynthetic rates per unit area
could be reduced while maintaining high yields. Earlier observation
of Wareing, Khalifa and Treharne (1968) that reducing leaf number
results in increased photosynthetic rates per unit area tends to
support Leeton's work. Stickler and Pauli (1961) used leaf removal to
determine the contribution of individual leaves to seed weight.
Although there were decreases in total grain yield, the relative yield
per unit leaf area increased. This indicated that as leaves were
removed from a sorghum plant the remaining leaves were able to
compensate for loss of photosynthetic area.
Reduced yield due to reduced leaf area has been reported by
several workers. In a study using hybrid corn, Acevedo, Hsiao and
Henderson (1971) found that under increasing water stress the rate of
leaf elongation decreased. Using a glass enclosure in the field to
obtain water stress. Stout, Kannangara and Simpson (1978) observed a
reduction in the number of living leaves on tillers and main stems in
two varieties of sorghum. In a study involving defoliation of Midland
grain sorghum. Stickler and Pauli (1961) reported decreased yields,
but increased photosynthetic efficiency per unit area.
Panicle and Yield
Photosynthetic contribution of the inflorescence to grain yield
has been demonstrated by many workers for the small grain crops. In a
study using barley, Porter, Pal and Martin (1950) observed the ear to
contribute 30% of the plant dry weight. This dry weight contribution
was only to the grain. Birecka, Skupinska and Berstein (1967), in a
study of spring barley, reported that the contribution of the ear to
photosynthetic activity of the shoot was 25% to 30%. At later stages
of growth this value increased to 80%. In a study with greenhouse and
field experiments and four wheat varieties, Watson, Thorne and French
(1958) concluded that the higher yields of two varieties were due to
increased photosynthesis in the ears. This increased photosynthesis
was associated with greater weight of ears. Using old and new
varieties of spring and winter wheat, Watson, Thorne and French (1963)
found that after ear emergence, ear dry weight of the new varieties
was significantly greater. Grain yield of new varieties was
significantly greater, but Leaf Area Index was not.
Eastin and Sullivan (1969) found that sorghum panicles having
more open growth pattern had higher head dry weights at all stages of
growth compared to compact type panicles. They attributed this
difference to the higher rate of photosynthesis occurring in open type
panicles. Fisher et al. (1976) has found the average contribution of
the inflorescence to the grain yield to be 13%. Eastin (1968)
observed that sorghum panicles intercept 40-48% of the total energy
due to sunlight from 9 A.M. to 3 P.M.
Stalk and Yield
The contribution of the stalk to the total dry matter of the
plant and its contribution of assimilates through translocation to the
grain yield has been studied extensively- Using pollinated and
unpollinated corn hybrids, Campbell (1964) found more total dry matter
to accumulate in the stalks of the unpollinated hybrids. In a growth
chamber study using wheat, Wardlaw (1967) found that when plants were
subjected to stress, assimilates moved out of the stalk to fill the
ear. The leaves were found to supply very little assimilates during
the grain fill period. Using sorghum, Herbert et al. (1982) concluded
dry matter stored in the plant prior to anthesis was later
translocated to the grain in some hybrids they tested. Fisher and
Wilson (1971) used dry weights of field grown plants to determine the
preanthesis contribution of assimilates was only about 12%. In a
study using maize having low leaf water potentials, Boyer (1976)
applied water stress during early grain fill. Photosynthesis ceased
at -1.8 to -2.0 Mpa (megapascals, 0.1 Mpa = 1.0 bar) and plants
remained inactive photosynthetically throughout the rest of the
season, but yielded 47% of controls. Shoot dry matter was reduced 21%
in stressed plants, being interpreted as evidence of translocation of
assimilates out of the stalk.
8
Number of Leaves
Sorghum varieties were shown to have four leaves in the embryo
(Clark, 1970). Additional leaves are initiated from the period of
planting to floral initiation, which is controlled by four maturity
genes (Quinby, 1972; Quinby, Hesketh and Voight, 1973). This period
has been shown to last about 30 days regardless of a variety's
maturity characteristics (Pauli, Stickler and Lawless, 1964).
Number of leaves of sorghum have been shown to decrease under
conditions of water stress. Using four different locations with
rainfall ranging from 31 mm to 413 mm, Vinall and Reed (1918) observed
reductions of from three to six leaves. They concluded lack of
moisture was responsible in part. In a dryland study of 21 varieties,
Sieglinger (1936) reported 19 to 27 leaves per stalk for Sorghum
vulgare Per. There were less leaves within a variety as planting date
became later. Bennett (1975) reported reduced leaf numbers for
sorghum under water stress.
Height of Plant
In sorghum, there are four known loci for height having a
cumulative but unequal effect. Significant fixable genetic and
environmental variation has been demonstrated for height of sorghum
(Hadley, 1957). According to Clegg (1969), plant height is an
important part of the crop canopy. On short stems, closely spaced
leaves may lead to serious shading of all but the top leaves. Tall
plants also tend to form a more complete canopy compared to shorter
plants under the same conditions. Working with tall mutants and the
dwarf plants they arose from, Hadley, Freeman and Javier (1965) found
that the heterozygous tall plants yielded more than the homozygous
dwarf plants. In a study using reciprocal crosses between 3-dwarf and
2-dwarf lines, Graham and Lessman (1966) reported that the tall (2-
dwarf) plants produced more grain than the short (3-dwarf) plants.
They speculated that more efficient light utilization by the tall
plants could be a factor in increasing grain yield.
Several workers have reported that water stress leads to a
decrease in plant height (Bennett, 1975; Stout, Kannangara and
Simpson, 1978). In a comparison of 3-dwarf and 4-dwarf isogenic
lines, Shertz (1970) observed reduced peduncle lengths for the 3-dwarf
lines. In a field study using sorghum under water stress, Bennett
(1975) reported decreased peduncle lengths for all genotypes tested.
Morphological Trait Correlations with Grain Yield
Most of the recent work involving associations of morphological
characteristics and grain yield have used common spring wheats
(Triticum aestivum L. aestivum group). Fisher and Kohn (1966b), using
a single variety of wheat, obtained a significant positive correlation
of 0.875 between grain yield and total dry weight at flowering.
Voldeng and Simpson (1967), working with seven lines of wheat,
obtained significant positive simple correlations ranging from 0.54 to
0.90. Correlations were calculated between grain yield and photosyn
thetic areas for both high-yielding and low-yielding varieties. In
their leaf shading experiments, dry weight of grain increased
significantly when the flag leaf and ear were left unshaded compared
to any other plant part left unshaded. Walton (1969), in a study of
high quality hard red spring wheat and Mexican strains, reported
10
correlation coefficients for extrusion length showed a close positive
association with yield. In a study of 120 lines of wheat, Simpson
(1968) reported correlations of 0.84, 0.91 and 0.93 between grain
yield and flag leaf lamina area, flag leaf sheath area, and total
photosynthetic area, respectively. Briggs and Aytenfisu (1980), using
seven wheat genotypes and six seeding rates, reported the most
frequent and largest correlations with plot yield were obtained with
extrusion length. Correlations between flag, leaf lamina area and
yield, and flag leaf sheath area and yield were positive when
significant. Ramos et al. (1983), working with barley, took plant
samples every 15 days from the single stem stage to harvest. They
found highly significant positive correlations between both leaf dry
matter and total dry matter and the corresponding leaf area.
Previous research leads to the conclusion that physiological
systems as well as morphological characteristics are affected by water
stress. Studies have been conducted on the effects of stress on
photosynthetic rates and yield (grain or dry matter). However, few
studies have related the effects of stress on leaf area and related
morphological traits to grain yield of sorghum. This study was
designed: (1) to determine if genotypic variation exists with regard
to leaf area and associated morphological characteristics, (2) to
determine the effect of two environments on leaf area and associated
morphological characteristics, and (3) to determine the relationship,
if any, of leaf area and related morphological traits to grain yield.
This thesis represents part of a comprehensive study designed to
determine genotypic variation and interaction with water levels and
11
development of breeding and screening procedures to be used in a
genetics and breeding program for sorghum improvement.
CHAPTER III
MATERIALS AND METHODS
Germplasm
Eight inbred lines of Sorghum bicolor L. Moench were planted at
the Texas Tech University farm in northeast Lubbock County, Texas.
Inbreds used were TX 7000, TX 7078, NSA 440, SC 56-14, SC 35-14, R
9188, TX 2737 and SC 170-6-17.
Field Layout
Field design was a randomized complete block with four blocks
repeated over two irrigation treatments, preplant plus one irrigation
(PP + 1) and preplant plus three irrigations (PP + 3). Each plot
consisted of four rows 6.7 m long with 102 cm between rows. Plots
were planted June 4, 1980. Plants were spaced 9.84 cm apart giving a
plant population of 96,500 plants/ha. A propazine herbicide (Milo-
gard) was applied post-plant at a rate of 1.2 kg/ha. Plants were
sprayed with pesticide (Sevin) as needed for insect control.
Soil type was a Pullman clay loam approximately one meter deep.
Plots were fertilized at recommended levels. Soil of both treatments
was brought to field capacity with a preplant irrigation April 28.
Two neutron probe tubes were placed at random within the same inbred
line in each treatment in the first and fourth replication to monitor
soil moisture. Both treatments received an additional irrigation June
30 which brought the soil to field capacity. The PP + 1 received no
more irrigations after June 30. The PP + 3 treatment received two
additional irrigations to field capacity, July 25 and August 30.
12
13
Additional rainfall received from June 8 until September 10 was 107.8
mm. All cultivation practices were carried out as needed in both
treatments.
The 1980 growing season was extremely dry for an extended period
with no precipitation recorded from June 12 through July 26 (Appendix
Table 1). Corn earworms (Heliothis zea [Boddie]) were observed in
plots, and control was obtained by use of insecticide (Sevin).
Characters Investigated
Five plants per plot visually judged to be at 50% bloom were
harvested by severing the stalk transversely at the soil surface.
Measurements were then taken on the following morphological character
istics. Plant height was the distance (cm) from the cut surface of
the stalk to the tip of the panicle. Peduncle length was the distance
(cm) from the flag leaf sheath to the basal node of the panicle. Leaf
area was calculated from the length of the lamina (excluding the
sheath) multiplied by the width of the lamina at its widest point
multiplied by 0.75 (Stickler, Wearden and Pauli, 1961).
Plants were separated into stalk, leaves and panicle and allowed
to dry at 50"C. Data were taken for each plant part dry weight. Head
weight was the mass of the panicle in grams excluding the peduncle.
Stalk weight was the mass in grams of the stem, leaf sheaths and
peduncle. Leaf weight was the mass in grams of the combined laminas.
Plant parts were weighed with a digital balance (Mettler).
After plants had reached maturity, 5.0 m of a center row were
harvested per plot for grain yield. Heads were weighed (kg) then
threshed using a plot harvester. The grain was then weighed again for
14
grain weight (kg). A digital moisture computer was used to determine
moisture percentage (%H20).
Measurements of morphological characteristics and grain yield
were used to make the following calculations:
1. Total leaf area - total of all the areas of all leaves on a per
plant basis (cm ).
2. Peduncle area - peduncle length times peduncle width times 3.14
(cm2).
3. Total photosynthetic area measured - the sum of total leaf area
and peduncle area on a per plant basis (cm ).
4. Threshing percentage equals:
(Grain weight after threshing / Head weight before threshing) 100
5. Adjusted yield, 15% moisture basis, equals:
(100 - %H20 / 85) (GNWT) C
Where:
%H20 is moisture content of grain as measured by moisture
computer. GNWT is the grain weight after threshing. C is a
constant (1960.78) for converting plot area into hectares.
Statistical Analysis
All data were analyzed for statistical significance using
analysis of variance for a randomized complete block design. Duncan's
New Multiple Range Test and simple correlation of all variables were
conducted. Computational analyses were carried out by use of the
Statistical Analysis Systems (SAS) at the Texas Tech University
Computer Center.
15
Least Significant Difference (LSD) values (Steel and Torrie,
1960) were computed to compare means of a genotype for a trait between
PP + 1 and PP + 3 water levels.
CHAPTER IV
RESULTS AND DISCUSSION
Morphological Characteristics
Analyses of variance of individual plant data for preplant plus
one irrigation (PP + 1) indicated highly significant differences
existed among genotypes. The PP + 3 showed more genotypic variation
for all traits except number of leaves. The larger variances due to
replication by genotype interaction in PP + 1 indicate more plot to
plot variability existed in the PP + 1 (Table 1). All morphological
traits measured were highly significant (P = .01) except plant height,
being significant at P = .05 (Table 1). The preplant plus three
irrigation level (PP + 3 ) indicated significant differences existed
among genotypes for all characters at the 0.01 probability level
(Table 1). As indicated by Table 2, combined analyses over water
levels resulted in highly significant interactions between water level
and genotype, evidence that inbreds responded differently to the two
water levels. Highly significant differences (P = 0.01) for all
traits except number of leaves indicate PP + 1 gave a different
response than PP + 3 due to water levels applied. Highly significant
interactions of genotype with water level were observed for all traits
except number of leaves. The data contradict results obtained by
Vinall and Reed (1918) of reductions under water stress of from three
to six leaves, and more recent results reported by Bennett (1975) of
reduced leaf number with water stress.
16
17
i o >-l
oc (0 di p
• H r-i
TJ di U
,jQ P
• H
>4-l O
CO j - t • H CO V4 4-1
i H CO O
•H 0 0
o rH O X a ^ o a p o
CO 4-1 CO
T3
^ O
ires]
. /••>.
o (30 <y» 1—I
CO iH (U > di
rH
P o • H 4-1 (0 00
• H
u u
• H
^^ <^
+ Ot OH
" ^
0) di
thr
CO 3
i H CU
4-1
c CO r H
pre
p
CO CO
CO di
s •>^>
di
a c: CO
• H Wi CO >
>4-l
o CO
•H CO >.
rH CO
c <:
. .—1
di r H ^ CO
H
1—(
+ 04 04 N_^
0)
c o CO 3
i H Od
4-1 P CO
r H
a a) u cu u di
"p p 3
o H
U •H 4J
H 0) CO x : CO
4-1 0) C M > . < : CO o 4J
o
CO
r H S-l CO < J 4-1 O >4-l
H CO di
<4H O
CO U di di >
X CO a <u 3 HJ
rH O CO p di 3 VJ
A4
rH X a 4J C3 00 3 C
di X
4J 4-1 P X CO 00
rH ' H
o
3 o
C O
o
cx> ON -3-
cn
m
CO
CM 00 o r—i
•K •K O 00 r>* cn r^ m
•K •K , — ( CTi
vO 0 0 m CN
•ic
ON
00
00
* CM m o cy> m -* 00
CN
CD
CJN 00 00
CN
ON
CJN ON
m
00
•K
CJN
cn
•K CO
CN
•K •K vO
O cn cn
* CO
cn cn
•K
cn
cn r-i CN ON
•K •K
m
\£> C3N
m
o
o
<r CJN o CN
•K
m CN
m
o
CO O
a
PC
o
(U
a 4J o c <u o
•K
m f—t
m
•K •K
cn m m CO
•K vO
cn
•K •K CM
CN CO
•K HC
O
•K •K 0 0
cn
cn
CJN
o
i n
cn
cn ON o cn
00 o cn cn en
in m 00
CN 0 0 o
• < r cn
I — I
oo m
00
m
cn
en CN
cn cn
cn i n o 0 0
ON CJN
cn CN
m
cn cn CN
CO
00 00
i n r^
CJN CN
CN
cn CM
cn CM
rH m
CN
CN
cn oo m
•K •K 0 0 ON
cn cn cn
o m
CN
00
CN 00 CN
CJN
m
O
X
PC
X
PC
p CO
rH PL,
CO 4-1
o
di >
a di a CO di u
X CO
X o u a
14H
o
di > di
o
o
c CO
m o
CO
4J P CO O
P 00
• H CO
I
>
o 0) a CO di
cn
+ (Xi Oi
c CO
(X, &4
)H o
di 3
rH CO >
18
u di > o CO di p
di u
X p
o CO
CO
CO O
• H O O o
rH o
X a u o 8 P o
CO 4-) CO
T3
CO di U CO 3 O" CO
p CO di
a
di o c CO
• H
CO >
rH CO 4-1 o H
4-1 di
X (0 4J (U c u >^< CO o 4J o
X Oi
CO di
rH U CO < 4-1 O t4-(
H CO di X
U di
X
a 3 Z
CO <u > CO 0)
hJ
rH O CO
3 t i T3 <
04
di rH X O 4J C 00 3 C
<U J O)
P X CO 00
rH -H 04 (U
o 00 CJN
CO • H CO >%
rH CO
5
CM
0) rH .Q
CO H
CO rH
> (U
V4
4J CO 3
•K •K 00
o r >d-«o cn ON CM
•K
* ON r «* m ON 00 r CN
CJN CM CN vO l *s . m
r - ( r H
vO ON r m
* * vO 00 r-4
O r^ m CJN
•K •K en o sr r>» r m CJN
•K * r 00 >3-oo >^ <J-1—4
•K •K CJ\ cn CN 00 >cl-- * r-4
•K •K CJN o m r^ 00 - *
•k •K CJN o 00 as 00 >^
<—4 -^ m cn cn CM
r«* •<r 00 •-d-
cn CM
«^ 00 CN \0 ON i n
vO -<J-CN cn as i n
cn o
cn
•K
m CJN
o
•K •K cn cn m
vO CJN
o
CM
HC •K
CM m 00 00
00
• m
CN
CJN
CJN
•K •JC cn
• ON \0 rH CN
CN
•K •K CJN
• C N cn cn
CM
CO ^
00 o
O N m -3-
•K •a CN
. r-4
vO ON
CN .
>* m
* * vO
• O cn o
•K •K cn
. o \D CM
* •JC O
• P^ cn
cn •
cn ,—t
r—1
. r-4
m
* •K r H
. ^ CN i-H
«* cn
vO •
o CN
* •K 00
• CJN CN O r H
•K •K r
. sr o cn
00 •
'«£) VO
r .
m cn
r H
. >^ P^ r H
\ 0 CM
>a-•<f i n CN
CJN 1—1
cn
di o u 3 O cn
/ - N
s >» rH di > di
rH
U di 4J CO 3
s Pi >^ p o
•H 4J CO o
•H rH a di
PC
o
di a
o p di o
o o X
065
o X
PC
p CO
CO 4-1
o H
X CO
X O U a
*4H
o
>
o o
CO
c CO O
c 00
•H CO I
•K
19
Absence of variation for number of leaves within an inbred line
could be due to irrigation June 30. This irrigation was applied
during growth stage one (GSI), the period of growth between planting
and panicle initiation. Both treatments were under comparable
environmental conditions during GSI which is the period of leaf number
establishment. All inbreds were subject to the same macro-environment
until the second irrigation in the PP + 3 water level. After panicle
initiation leaves are no longer initiated and leaf cell expansion
would then be the major determinant of photosynthetic area. Leaf cell
expansion in response to additional irrigation water may have been a
major contributing factor to the highly significant differences in
total leaf area indicated between water levels (Table 2).
Dry Weights
Analyses of variance for dry weights in PP + 1 and PP + 3 provided
results similar to those obtained for morphological characters, with
highly significant genotypic differences for all traits (Table 3).
When analyzed over both irrigation levels, genotypic differences were
highly significant (P = .01) (Table 5). Water level by genotype
interaction was highly significant (P = .01) for leaf dry weight and
plant dry weight, and significant (P = .05) for head dry weight and
stalk dry weight (Table 4). This indicates water level had an effect
on dry weight causing the relative position of a inbred line to
change. Such genotype by water level interaction for traits measured
indicates certain inbreds perform better relative to the other inbreds
under higher or lower water levels. Therefore, inbred lines will
20
u di
T3
P 3
t O u 0 0
CO CU * P / - N
• H O rH 0 0
ON T J r-H 0) > - • IH
X CO C r H
• H di >
U di O H
>4H
p CO O 4-» - H J= i J 00 CO
• H 00 (U - H :2 V4
V4 >^ - H U
TJ / - ^
cn 4J
c + CO rH (X,
a. oi c O (U
(U CO }H
CO 4-1 T3
CO *4H 3 O r H
a
res)
ant
squa
repl
a 3 CO 'P di P a CO
/'^ <U ,-4
o p + CO
• H OH M OH CO ^-^ >
CU 14H C
o o CO CO
• H 3 CO r H >% CX
r H CO 4-1
<i CO r H
cn u a
ble
CO H
4J
x: 00
4J ^H C (U CO : 2
r H
0 >^ V4 Q
4-t J= 00
• H 14H CU CO S (U X >,
u a
4J X 0 0
i H di CO S 4-) CO >^
o
4J
00
CO <U <u :s
^4 Q
»4H
(U O
3 O
CO
O 0 0
r m 0 0 0 0 m ,-i
cn cn
cn cn O CM I—(
CN CJN
CN m
<—4
-»-- t - • • -
CN m
^ o r-4
en
/"-S
0(S
p o
• H 4J CO O
• H r H
(U Pi
* * 0 0
0 0
o cn <—4
•K •K
•
m r-H
•K
cn 0 0 i n
O
cn ON
r
o
CU
a > 4-1
o c (U
o
•K •K '^t
sO >;t
CM
•K •K cn
• CJN 0 0 CN
•R •K -3-
r>. i n 0 0
•K •K
m m
T—4
•K r-4
o ON CN
•K
• •<d-
•K
m •<f CJN
•K
cn
o r—4
r-4 CM
o X
PC
v£>
S t O cn
CJN
cn cn
0 0
i - H
ON
0 0
CN r H
0 0 CJN
r H 1-H m cn •-i CM
r cn
m cn CM CM
O r^
r^ 0 0 s r v£)
CJN o
c n 0 0
0 0 CN i-H
^fS^
o X
s-x
4-1
c: CO
r H OH
CN r H
O N O O
CM cn CN c n
s f ST
• • m \o cn cn
r^ vO
0 0 v ^
r-4
0 0 s r
0 0 m r H
ON
m ^H
r H CO 4J o
. >^
r H <U
> • H 4-1 O CU a CO di u
M
>% 4-1 • H r H T H
CO j Q . O >% U TH
evel of p
espective
I-H U
t—4 *
o cn o + •XJ OH
P OH CO
T3
0.05
1 an
^ + CO
OH •M OH
C CO U
o o <4H •rH 0) C 3 00 rH
•rH CO CO >
• 1
1 1
•K - ( -•K - t -
•K H -
21
o 0 0 ON
CO rH di > di
u di 4-1 CO
U di >
o CO 4J X 00
•H di
u 'p
p CO
u o
CO 4-1 CO
c o
CO CU u CO 3 o* CO
c CO (U
a 0) o c CO
• H V4 CO >
*4H O
CO • H CO >%
rH CO P
<
(U rH X
CO H
X 00
•H 0 13 4J
3 CO
* * 00
• CN O cn r H r H
St •
vO 00 cn
•K -K CN
• m o r>» CM
* * o
• o m o r H
•a cn
• r CJN CM
00 .
r-4 ON rH
CM •
00 ,—1 cn
X 00
•H 0)
3
CO <U
X 00
• H (U
rH CO 4-1 C O
•K •K 00
. t n
cn
cn
* •K CJN
• CN o cn
•K •K O
• cn S t
•K cn CJN
cn
m
S t CN
(JN
cn
•K •K r>>.
. rH i n CJN
o • <JN
o <-4
•K •K 0 0
. rH vO r-4
•K CJN
. 0 0 r>» c
•K I-H
. cn CJN
CTN
. r i n
m .
00 CJN
X 00
•H (U :s TJ CO di X
* •K 1—4
• o o 0 0
00
•K •K vO
• vO CN CM
•K CJN
. 1-4
cn
•K •K m
. 1—4 1-4
CJN •
i n
m .
»d-1—4
v£> CN S t m
CN
ON 1—4
cn
di o u 3 O
CO
di > di
u d) 4J CO 3
Pi
p o
CO
CU
oi
o
(U a >% 4-1 o p di o
o X
: 2
X
O
X
OJ
4-1
CO
CO u O H
di >
O lU a CO 0) VH
CO X o u CU
di > di
o «
o c CO
m o
4J CO
C CO
a
p 00
•H CO
I
•K
22
" O CO (U rH U di
X > c <u
u p o o
»4H " H 4 - 1
CO CO 4 - 1 0 0 • H - H
CO U
u u TJ / ^ ojcn
>H OH
OH
-O ^
§ <U (U
r H X 0) -1-1
• H >N CO
3 C r H
• H O . CO
0 0 c CO
r H (U a . ^j
p ^
o + ^-N
CO CU u CO 3 o* CO
OH OH N ^
(U c o CO 3
ian
ce
CO >
MH O
CO •H CO >>
rH CO P
<
•
epla
r
M
M (U
TJ C 3
C ^ o >H 00 .
/»-> CO o (U 0 0 c: CJN
i n "H r H rH v - /
(U
r H
CO
H
00 0) C 00
• H CO J = 4-) CO c di di u o X u
OH
TJ di T j 4J rH CO (U 3 • H
• f - ) >4
<!
0) (U 0 0 M CO 3 4J 4-1 P CO 0)
• H O O »H S <u
OH
00 • H
U di o :2
r H OH P
CO
X 0 0
4-t - H O di
rH :s O H
T J CO 0)
(U O u 3 O
CO
0 0 CM
CN CM
•K •K 0 0
• 0 0 CN
•K
O CM
O St cn ON
o CM 1—4
•K
m en o CM
•K •K <N S t 1—4
CN m cn
cn cn
m CN St
m en
m cn m o
• K •JC ON CJN
so m m
. cn
ON 0 0 >3-CN vO 1-4
vO CJN S t O m
CN CJN 0 0 o CJN
cn
O CM m ON S t cn
NO
St
CM
cn
VO CM
o
sO r-4 O
o
•K •K vO ON CN
>ct CSI cn
i n CJN 0 0
rH O
CN « * S t f - ( O O
ON
o CN r-4
.
o
cn
•K S t CN 0 0
•K •k N O St m
CJN O
S t 0 0 O
PC
c o
CO
cx di
PC
o CN
CJN St O
o CM
S t O N
cn
CN
O
CU P.
4J o c CU
o
O X Pi
cn
CO 4 -1 o H
• >» u •H r-i •H X CO
-Q O u p.
MH
O
rH <u > <u r-i
r-4
o •
o 4J CO •
4J P CO a
•H l+H •H C 00
> •H 4-1
a (U a CO <u u «\
cn + OH OH
TJ P CO
r-4
+ OH OH
U O
14H
di 3
rH CO >
CO
•K •K
23
need to be evaluated to determine such responses to water. Depending
upon correlations between related traits and grain yield, particular
inbreds may be better suited to certain water levels. Of special
interest are those types capable of maintaining performance at lower
water levels as well as having the capability to respond to greater
water availability.
Grain Yield and Related Traits
Analyses of grain yield and related traits for PP + 1 and PP + 3
indicated highly significant differences (P = .01) existed among
inbreds (Table 5) indicating genetic variation existed among inbred
lines for grain yield. When analyzed over water levels, highly
significant genotypic differences were observed with all traits as
indicated by Table 6, providing evidence of genotypic variation for
all traits. Genotype by water level interaction indicated a
significant (P = .05) difference. However, plot head weight, plot
grain weight and adjusted yield indicated no such interaction.
Interpretation of this lack of interaction is that the relative
position of an inbred line did not change over the two water levels,
and a change in unthreshed head weight at harvest did not affect grain
yield relative to other inbreds.
Significant genotype and genotype by water level differences for
most morphological traits and all dry weights is evidence of
differential response to water availability among inbreds. However,
significant genotypic differences for adjusted yield, but no genotype
by water level interaction, indicates that additional water was used
for vegetative growth, not reproductive growth. Such a response was
24
o 0 0 CJN
CO rH di > di
u di
4-1 CO
u di > o CO 4J
o rH
a 13 rH di
o 14H
CO 4-> CO
p O
CO
di
CO 3 cr CO
P CO CU
a (U o c CO
• H >H CO >
o CO
• H CO
>, r H
CO P
<
X
di r-i X
CO H
00 <u C 00
•H CO X . u
CO c (U di U (J X u H <U
OH
T3 <U T3 AJ r H CO (U 3 "H
•O >H TJ <
di u 3 4J CO
• H O
s
00 CO 4-1
p di a >H di
O)
x: 00
• H 4 H CD O S
r H OH C
• H CO U O
x: 00
4-1 • H O (U
- H S OH
CO <U
di o U 3 O
CO
1—4
• rH - * CJN
CN •
m CM
•K -K m
• o o Csl
- * •
0 0 S t
CJN •
CM CM
CM •
vO r
•K •K
m CN r-4
cn o 0 0 0 0
o m cn r r
•K * 0 0 CN O vO
cn cn CN
CJN 0 0 vO CJN r H CN
CM CJN S t <JN
o I - H
CM vO O >* o m
•K •K O O CJN
• vO S t
S t 1—4
vO •
O
•IC •K ON
o 0 0 .
vO
•)C •K
r <* m . r-4
0 0 CJN CN
. o
o cn ON
. r-H
•K •K
-^ cn o
i - H
CM O
•K •K
m vO
m m m o
0 0 CN o
CM CN r-4
CN
•K •K O 0 0 CM
• S t CM
0 0
o I - H
. o
•K •K
>* r>» r-4
. CN
•K m (JN r-4
. o
CJN
r O
• o
CM r-4
r>. .
o
1-4 v O
: 2 PC
CN cn
di > di
u di 4J CO
p o
• H 4-1 CO O
di Pi
o
CU
a 4J o p di o
o X
o X
0:2
CO 4-1 o H
(U >
o (U a, CO (U
•IH
CO X o u a
di > di
o o -p
p CO
m o
CO
p CO O
P 00
• H CO
•K
25
observed when averaged over all inbreds, but may not accurately
describe individual response.
In a breeding program, inbred lines would be evaluated on ability
to produce high grain yields over a range of environments or developed
to be grown in a particular environment. Those inbred lines with the
ability to produce a high grain yield in relation to vegetative matter
when water is limiting would be selected. Lines able to partition
development in this way may indicate other factors such as
photosynthetic rate, root depth and density, or early maturity are
influencing grain yield in addition to leaf area and related traits.
Other influences could be the time at which the plant begins producing
photosynthate for grain fill and also the amount of photosynthate
stored before grain fill begins. These elements need to be evaluated
to determine their effect on the grain fill period and final grain
yield.
Morphological Trait Means
Means of plant heights for PP + 1 were generally lower than means
for PP + 3 (Table 7). Most inbred lines were reduced in height by 20
cm or more, but TX 7078 and NSA 440 indicated reductions of 12 cm and
13 cm, respectively. TX 7078 was the shortest in both water levels
and was significantly different (P = .05) from all other lines over
water levels (Table 7). NSA 440 was not significantly different from
the tallest line in PP + 1 and was third shortest in PP + 3 (Table 7).
Although TX 7078 and NSA 440 showed the least change in height between
water levels, both inbreds were significantly different at P = .05 by
LSD test (Table 7). Using the LSD value of Table 7 to compare each
26
c: CO
O4 OH
(U P O
CO 3
p CO
rH a CU u ex
;H
(U T1 3 3 ^ F 0 u 00
CO (U
c •H i H
-o (U u X p
•H
0 00 CJN I - H > « •
CO r-i di > (U
rH
u di 4 J
CO 5 u di > 0
TJ P CO
CO rH CU > di
^
CO 4-1
•H CO M •u
rH CO 0
•H 00 0
H 0
X ex >H
0
a 14H 0
CO p CO (U S
. r*
di rH X CO H
CO 00
•H SH M
•H
/ ^ S
cn
+ OH OH
• ^ ^
(U (U u X 4-t
CO 3
rH CX
4H
rJ CO
r-i CX (U >H
CX
0 4 J
0 X OH
rH CO 4-1
0 H
UCN •H / -> 4J a di 0
X ^ u P CO >^ di CO u
<
<4H CO
a) /~\ i J COCN (u a rH M O CO < - ^ 4-t
o H
u di
X
a 3 z
14H 0
CO (U > CO di X
di r-i / - ^ CJ COcN P di B 3 M U
TJ < >-' (U
OH
(U H X O 4-1 •-N 3 00 a 3 c a
TJ CU >-» <u J
OH
CO 00 a rH •H O OH <U >-'
0) CX >% 4-t o p di o
T3 0
^ X
vO 0
1954.
2819.
•p 0
X 0
CN <JN
1939.
2782
(U T J CU
m CJN
00 00
0 . 0 X
S t r H
i n X rM cn
0 X 0
ON r H
i n r-l I-H
di 'p
00
vO 00 cn CM
TJ 0
0
r H vO cn CN
(U
r>
00
X
00
m CM
0 X
i n
00
- 1 -•K 4 -0 - t -
XJ U3rH CO CO ^
cn CM
CJN i n 1 - . 0
r^
TX 7000
CM
CN CJN
•p 0
CJN cn
ON r^ m I-H m CJN r-i r-4
T3 TJ
0 0 r H
S t r H « * i n m ON r-4 r-4
di di
CM m
00 00
X TJ
C N CM
m 0 r H CN
U X 'P
ON so
m vo
u -0 r H r-4
m r r^ 00
00
0 r
X H
14H
X
m NO
r-4
<4H
CJN
r-4
di
en
00
U X
r
r H
0
CM
NO
(U
r-4
r-4
00
CO
NO
CM
vO CN
CO
vO
NO NO sO CN
, 0 CO
CJN
0 r-4
X
CJN
m
' p 0
CJN
r-4
X CO
f^
r-4 00
CO
CM
cn 0 m cn
CO
CN
r-4
i n cn
0 X
NO
0 r-4
di
0
CN
<U
NO
0
CJ
i n
ON
0 • ^ • ^
< : CO
z
CO
CJN
00 0 cn
CO
<JN
cn 00 0 cn
0 X
00
0 r H
TJ
0
«*
T3
Csl
r-4
13 0
r-4
00 00
abc
-d-
00 m CM CN
0 X CO
r
m CM CM
1 3 CJ
i n
CJN
X
r
en
1 3 0
CJN
r H
0
CO
as
00
CO
- *
00 cn I-H
cn
0 X
CO
0
00 CJN
cn
13
0
0 1—4
X
- *
0
X
>*
sO r-4
X
sO
cn 0 r-4
r-4 1
sO
i n
u CO
a X
-^
00 CJN vO CN
a X
^
sO
vO CM
13
00
CJN
X
0
CN CM
X
r-i
CJN
0 ^
CN
r-4 CJN
CO
0
m <JN
cn CN
CO
cn
m cn Csl
CO
0
CM r-i
CO
r>»
cn
CO
00
CN
CO
Csl
m 00
X CO
00
O N
cn
0 X
CN
ON
0 cn
CO
CM
CM r-4
CO
SO
0 r
CO
r
0 CM
CO
cn
0 1—4
1-4
1—4
1 i n cn 0 CO
X CO
- *
CM
CN
X
CN
00
r-4
CN
CO
1-4
CN r H
CO
CM
-3-m
CO
00
sO 1—4
CO
r>
CJN
'P 0
cn
0
r-4
13 0
r>.
i n
I-H
X CO
-^
r-4 r-4
X
vO
m r-4
X
00
r*.
X CO
ON
CN 00
>4H
u <u
CM Csl
00 CM 00 00 r-4 r-4
(4H 13 di
sO r H
i n m i n 0 00 00 r-4 ,-4
X X
cn cn
r H r-4 r-4 r-4
•P a X
sO r-i
00 CN CN CN
X X
m CM
« * r-4 r-4 r-4
X X CO CO
0 0 c n
m St 0 CJN — 4
00 00 r-4 CJN
PC
27
• • •
13 01 3 3
• H 4-1 P O o
. r-.
di rH
X CO
H
1 O CJCN 4J - H / - N
o u a X CU u O H j C s - ^
4-t r H C CO CO > , CU 4J CO VH
o <: H
(4H CO di ^•^
X COCN
(u a r H V U CO < ; v w 4J
o H
CO U di <u >
. O 14H CO a o <u 3 HJ
Z
CU r H ' ^ CJ COCM 3 CU a 3 (H U
"^ <3 ^-^ <U
OH
(U r H X O 4J ^-N 3 00 a 3 C O
1 3 CU ^ 1 ^
di X OH
• U 4.) 3 ^ ^ N CO 00 a
r-i -H O OH at >-^
ffi
0) CX >s U
o p di
o
TJ U
^ CO U
•^ so m . . .
-d- CM cn r-4 r-4 r-4 r-4 r-4 r-4 CN CN CN
O X di CO 1 3 13
CN ON o . . .
cn CN cn rH CJN O r H O r H CM CM CM
O T3 13 ^ O CJ
- ^ CJN r H
. . . O CJN O r H r-i
-P - Q U O
CN r^ m . . .
r H CJN O r H r-4
1 3 1 3 13
c n s O r H
. . . o m cn
CJ XJ O 13
ON r H m . . .
sO sO sO r^ ON 0 0
r- cn r>. CM
X H
U X X
CO CO cO
m o CN . . .
m ON CN r-i O r-4 cn cn 00 CM c n CN
a XXX
CO CO CO
cn p^ o . . .
P^ 0 0 - * o o o cn cn 00 CN c n CN
X ^ X CO CO CO
cn m -^ . . .
r-4 r-4 r-4 r-4 1—4 r-4
X d) Ti
CN c n CM . . .
0 0 CO 0 0
1 3 U di
X "P "P
O cn CN . . .
cn cn cn
o X o CO U3 4 2
>^ o r>. . . .
ON CN O r^ O CJN
I - H
-17
vO < 1
o r^ r ^
<J> CO
cn •
o <JN SO
Csl •
CM as sO
1.4
0 0 •
- * r-4
CN •
m
m •
0 0
•M i n
o •
o Q CO X
1 u di
>4H <4H • H 13
> N
rH u
iflcan
c 00
• H CO
4-t O 3
ter are
4J CU
r-i
same
by the i
t.
y^ di 5 ^ O di
J C>0
o S
column f
Itiple R,
3 <U jg a " CO 3 CO Q)
Z di
ent in th
Duncan's
a >N 4-> X CO d) M
u i n 4-t O
• CO
II u O OH
14H U
CO CO
c CO 4-1 <U P a <u 1
•K
, 4 J
f H • CO
>>> U rH -U CU
spectiv(
s for a
CU rH
vels, r
er leve
water le
ween wat
4-1 >H 0) di X > O d) CX
1 3 >^ 3 4J
P + 3, a
f a geno
OH O
M CO rH 3
CO
+ <u a
ue for PP
omparing i
rH O CO > Ul
o CO M H
0) 4-1 (U O 3 C rH (U CO
1 3 >
1 1
•-H CN
A
-«— +-
M
+-
28
inbred's value for height in PP + 1 with its value in PP + 3 indicates
no inbred maintained the same height under varying water regimes.
This gives evidence of significant increased vegetative growth with
increased water availability for all genotypes tested.
A positive association of plant height with adjusted yield (Table
12) indicates selecting for plant height would have a positive effect
2 on grain yield. However, this correlation resulted in a r value of
0.09, indicating the relationship was of no great biological value.
Tendency of tall plants to lodge as well as the difficulty encountered
in combine harvesting of tall plants would likely inhibit selection
based on this character. Selection of an inbred with stability for
height over a range of environments could lead to efficient light
utilization referred to by Graham and Lessman (1966).
Peduncle length means were related to plant height means (Table
9), taller plants having the longer peduncles as a result of internode
expansion. Change in peduncle extrusion length was most dramatic for
SC 56-14, being 1.9 cm in PP + 1 and 16.4 cm in PP + 3 (Table 7).
These values are shown to be significantly different by LSD test.
Lines TX 7078, NSA 440, and SC 170-6-17 had relatively small changes
from PP + 1 to PP + 3 with SC 170-6-17 being essentially constant, and
values for these lines are not significantly different when tested
with the LSD value. Decrease in peduncle extrusion length under water
stress is in agreement with results obtained by Bennett (1975).
Stability of peduncle extrusion length over various environments would
be a selection criteria from the standpoint of ease of combine
harvest.
29
Degree of peduncle extrusion beyond the flag leaf sheath is the
result of expansion of the uppermost internode. Highly significant (P
= .01) positive correlations between plant height and peduncle length
at both water levels (Table 9) indicates for these inbred lines
overall internode expansion is related to peduncle extrusion length.
Plants having more internode expansion would have a more open growth
pattern which could allow for greater light utilization.
Means for number of leaves in PP + 1 and PP + 3 indicated that the
taller plants (SC 35-14, R 9188, and SC 170-6-17) had the greater
number of leaves (Table 7). This can be explained by number of leaves
being directly related to internode number, and height of plant being
due to internode expansion. Lines maturing at about the same time,
but having differences in leaf numbers, would be expected to have
different rates of leaf appearance, the inbred line with more leaves
having the faster rate of leaf appearance. Since peduncle length is
related to plant height, genotypes with more leaves would be expected
to have longer peduncles due to the relationship of height and
internode expansion. This was generally the case except for peduncle
length of SC 170-6-17 which was essentially the same for both water
levels. This could be due to leaf sheath length; however, no data is
available for this trait.
Height decreased from PP + 3 to PP + 1 for all inbred lines (LSD
significant) up to 25 cm for SC 35-14, but no corresponding decrease
in leaf numbers was observed for these inbreds (Table 7). This
contradicts results obtained by Vinall and Reed (1918) of reductions
of from three to six leaves in sorghum under water stress, and by
30
Bennett (1975) who reported a decrease in height and leaf number. The
lack of variation in leaf number could be due to June 30 irrigation
near panicle initiation. Variation in height leads to the conclusion
that internodes were expanding at different rates, but no variation in
leaf number indicates the same stress for both water levels while
leaves were initiated.
Means for leaf area and total photosynthetic area gave results
similar to those obtained for all other morphological traits in the PP
+ 1 and PP + 3, being greater in PP + 3 than PP + 1 except for TX 2737
(LSD not significant) which produced essentially the same leaf area
under both water levels. Leaf area reductions ranged from 6% for R
9188 to 30% for TX 7000 and SC 170-6-17. TX 2737 was observed to be
early maturing and senescent which is evidence of drought escape
mechanisms referred to by Keim and Kronstad (1981). Early maturity
could lead to increased cell expansion rates in the PP + 1, and thus
increased photosynthetic area.
The significant genotype by water level interaction for total
leaf area, but no significant difference for leaf number (Table 2),
indicates leaf expansion was the primary factor causing increased
photosynthetic area in PP + 3. The significant negative correlation
for total leaf area and adjusted yield (Table 11) gives a r^ value of
0.151 indicating increased photosynthetic area increased sink size and
was possibly competing with the grain filling process for photosyn
thate. This can be seen from means for total leaf area of SC 56-14
and NSA 440 (Table 7) and adjusted yield (Table 8) of these two
inbreds. Although leaf areas for these lines were largest in PP +3
31
CO 3
rH CX
4J . 3 ^ CO O
rH 0 0 O.CJN di r-4 U ^w'
a CO
U r-H CU di
-o > 3 <U 3 ^
r ' ^ ^ d^
}H 2 00 ^
rn '-I
3 > •rH
_ 3 1 3 CO (U >H M
•2 •-' 3 a; • H >
0) U r-i O
<4H 3
o - r t T H
r H -W flj CO
• H M > ^ • H
U
^ H • H ^ CO U ^ bO^
^ + 4-t
^5 13 di 3 CU CO M
J= CO 4-t 4-t X CO 0 0 3
•H r-i di CX 5
4-t
>N 2 tH «J
TJ rH CX
4_, 0)
3 ^ g CX
^'B CO
14H
o ^ r H
CO
c + CO
i i OH S OH
<>-•
. (U
0 0 3 O
di r-i X CO
H
0 0 3
• H J 3 CO di u X H
0) U 3 4-1 CO
• H O
s
1 3 0) 4-t CO 3
di 00 CO 4J 3 ^-> <U ^ 8 U > ^ U di
OH
0) 0 0 CO 4-> 3 /-^ Oi ^ S O > ^ M CU
OH
CO ^"^
X o CN
00 X M ^ >«• m
•«-) T3 r H 1 3 <
3 • H CO Ui O
4-t
o rH OH
TS CO di ffi
4J
o r-i OH
4-1 3 CO
rH OH
14H CO 0) X
^ i H CO 4-t CO
1 3 CO di X
rH di 4-t
• H CO >•
4-t X ^-s 00 0 0
• H ^ (U s ^
3
4-t X / - s oo 00 •H M 0) s ^ 3
4J X / - s 00 a
•H 00 CU v - /
S
4-t X '^ 00 a
•H 00 01 >^ :s
4-1 X ^-N 00 a
• H 00 (U ^ ^
:5
4-t X ^ 00 a
• H 00 di v ^ 3
0> CX >s XJ O 3 di O
a ^ CO
so o vO
cn
di 1 3
m cn
cn
CO
CJN ON CJN I - H
CO
O O
r-4
CO
CJN r^
r-4
O
cn S t
r^ cn
T3 U
sO m
en r-4
CJ ^
sO cn
0 0 r H
- ( -•K . O
r H
m •
i n
X
0 0 CN
so cn
T3 O
m rH
CN
X CO
o i n
cn CM
X CO
sO 1—4
1—4
CO
ON 1—4
cn
X CO
cn so
cn so
CO
r m cn CM
a X
o so 0 0 CN
1 3 U
r- r-4
sO
cn
a; 13
m t ^
CN
CO
>* r^ r-4 CM
CO
0 0 O
r-4
CO
CJN - *
CN
o X
CN
m o m
o X
sO i n
0 0 r-4
X
0 0 S t
cn CM
- t - r H
+-X
sO S t
•
TX 7000 11
u X
0 0 ' ^
• 0 0
CO
0 0
o CM vO
di
0 0 0 0
CM
X CO
sO CJN
m r-i
X CO
ON
r O
o X CO
0 0 CM
I - H
o o m m cn
T3
CN cn
CN r-4
o i n cn
m r H
CO
cn 0 0
r^
CO
m cn 0 0 S t
'p
cn r-4
CN
CO
1-4
0 0 vO CN
CO
CM cn
r-4
X CO
cn t*>.
CN
1 3
i n
o 0 0 - *
X
m o p^ r-4
1 3
ON O
o CM
X
1—4
CJN
o
TX 7078
1
CO
r-4 CM
m m
o o m CM
CO
0 0 cn r-4 CN
CO
sO O
r-i
X
r-4
o CM
1 3
0 0 P ^
r-4 •^
13
CJN sO
S t r H
u CM r^
t ^ r-4
X
r^ cn
<3N
'P a
CN r-4
0 0 S t
u X
0 0 r>.
be
14.
CO
sO 0 0 cn r-4
X CO
O r^
O
CJ X CO
r>. S t
.—I
CO
0 0 r-
CJN
m
CO
CM r^
CJN r-i
CO
r^ O
r-4 cn
CO
as CJN
0 0
X
0 0 CM
so cn
13 o
m 1—4
Csl
a CM 0 0 so r-4
o cn 0 0
o
CJ
CJN CN
CM
CO
m sO
m p^
CO
r-4 S t
S t CM
CO
r-4 1—4
r^ cn
CO
cn r-4
<T
NSA 440
1
1 3
O CN
CM S t
O X
X S t
cn
X
<f cn m 1-4
X
p^ p»*
o
o X
0 0 0 0
r-4
CO
r-l r^
r* vO
CO
so O
Csl CM
CO
CJN O
S t cn
CO
sO i n
r H 1—4
13
m -^
so «*
X CO
0 0 CM
i n
13
S t CN
cn
u r>. r-4
O
13
so cn o
X CO
ON
o eg
m
X CO
m p^
0 0 r-4
CO
-^ CM
ON Csl
X
o r-4
<t
X
CJN 0 0
CJN cn
X
m r^
CN
T3
r-4 CM
o r-4
13
1—4
m o
13
0 0 CM
1-4
X CO
(JN cn
cn vO
CO
CN
m rH CN
X CO
CJN S t
-^ cn
13
o 0 0 cn
p»«
SC 56-14
13 a
r r H
cn <*
X
r-4
o S t
O
CN r~«. vO
o -* cn o
13
c^ 0 0
o
X
m p ^
p^
m
X CO
-d-1—4
o CM
CO
1 ^ 0 0
r-4
en
1 3
S t f ^
m
1 3 CJ
CJN sO
p^ S t
CO
o o so
13 CJ
cn o ON
X
r^ >3-
O
a p>. ON
o
X CO
CN vO
r-4
m
X CO
cn i n
CJN r H
CO
sO r^
r^ CM
X
cn cn
'^
X
sO r-4
m en
CO
i n CJN
- *
a r-O sO 1—4
U
Csl 0 0
o
o cn cn
CN
o X
cn CJN
o vO
CO
CM CJN
O CN
X CO
sO > t
cn en
13
m m sO
SC 35-14
T3
CM •<t
r-4 <f
CO
0 0 •^
m
X
i n
m CM r H
X
•<r sO
o
u i n sO
r-4
X
CJN CN
sO
m
X CO
CM CN
o CM
CO
1—4
SO
O cn
13
vO -d"
m
13 CJ
X
oo 0 0
CJN 'd -
X CO
cn en
i n
o X
r-4 CM O r-i
X
CvJ
m o
CJ
X
S t
o r H
u X
CN r H
SO •^
O .o sO P^
S t i -H
CO
cn o r^ CN
X
en cn
S t
CO
r^ sO
vO
-a-
1 3 O
^
O cn
eg
X
CJN r-4 r-4 CN
^
m o r-4
o i n CN
CN
T3
cn o S t -3-
X
o p^
m I - H
13 O
-^ CJN
Csl CN
13
ON cn
i n
R 9188
CJ X CO
0 0 Csl
0 0 - *
X
r-4 0 0
cn
X
o p^ i n f—i
X
CJN r^
O
u >3-so
r-4
1 3 U
r< O
i n S t
'P
CN Csl
i n r-4
X
CJN CJN
- * CM
13
SO OO
• > *
32
• • •
13 di 3 3
• H 4-t
3 O
CJ
. 0 0
di r-i X CO
H
00 di p 00
• H CO X U CO 3 / ^ 0) 0) 3sS (H U N.^
J 3 U
H 0) OH
di di 00 ^ CO 3 -i-t 4-t 3 ^-s CO (U 8 «
• H CJ s - / O (H
S (U OH
CO / " ^ 1 3 JS O CU - ^ eg 4J 00 JC CO ^ S^ 3 's^^ i n
•"-J 1 3 r H 'P rH - < 0) 4J
• H CO
3 • H CO 4H M J= / - N
O 00 00 •H J«i
4-1 0 ) s.-^
o s r H OH
13 CO H
pd 00 00 • H ^
o s r H OH
4H 4-1 3 - C / - N CO 0 0 a
r H • H 0 0 OH 0) v .^
13
4-1 14H ^ x -s
CO 00 a 0) -H 00
hJ <U > - / : 2
. 1 ^ 4-1 r-i X ^-\ CO 00 a 4J - H 00 CO 0) > ^
: 2
4J 13 J= /-s CO 00 a (U •H 00
PC QJ >w' 3
0) CI. >. 4-1 o 3 0)
o
1 3 O 1 3
X X U
CM CjN r H m <* m
. . . o o m m S t S t
1 3 13 o -o CJ ^ o
o in cn o >a" CM
. . . •>* CM c n r H r-l r H
a X CO CO CO
P*. ON 0 0 r H cn P>. i n so o r H CM CM
X CO CO CO
SO r H S t (^ cn o
. . . O t—1 I-H
X CO CO CO
rH - ^ f ^ m CM cn
. . . r H r n CM
^ 1 3 O CO O XJ
r H P^ ON r H sO c n
. . . CN O r H i n m m
o X 1 3 CO ^ U
CM so - ^ St so m
. . . r>. in so r-4 r-4 r-4
13 O X
r^ 00 r>« cn r^ O
• • • i n >d- m CM eg CN
^ X X
CM c n 0 0 c n CN p^
. . . ON O CJN
r-4
ps*
cn r^ eg
X ! H
X X CO CO CO
CM 0 0 O r H sO ON
. . . 0 0 P^ CM St -^ m
0) O 13 'P X o
O cn r-4 p^ r^ CN
. . . cn CN cn r-4 r-4 r-4
X CO CO CO
ON r H O cn CN cn 0 0 S t r H rH CN CN
X CO CO CO
CM O sO ON CM O
. . • ^ r-4 1—4
o Cd X X
00 cn so m m o
. . . r H eg CN
O X X Cd X
0 0 c n r H s o I-H -a-
. . . vO O 0 0 S t p^ m
o X X CO CO CO
ON CN sO O so 0 0
. . . 1 ^ -d- O .-H CM eg
X CO CO CO
so ON r>. r H c n CN
. . . S t ^ O eg cn cn
a X X o
c n CN 0 0 >3" r H CN
. . . m ON p^
r-4
1 sO 1
o
r-4 CJ CO
S t 0 0
. sO
0 0 r>.
. o
0 0 CN < •
>^ CM
• O
o S3-
•
O
0 0 r^
. CJN r-i
P^ o
. p^
so 0 0
• o 1—4
P^ ^
• m
rM i n o
• o
CO X
1 <4H • H 13
>> rH 4J 3 CO
o • H ^ • H 3 00
• H CO
4J o 3
ter
are
4J di
rH
di
a CO CO
CU
X 4J
>^
— ui y, CO ^ di
r-i (D
1 3 ^ Cd
PC 4-1 ^ 3 (u ^ - H a CU
reat
Lilti
^ s <U 5 a CU CO <z CO
CO
the
can'
3 3 • H 3
a 3 a > 3 X
rH o m o o
• CO
It 3
• H OH X 4J 4J • H CO
4J CO 3 3 <U CO V4 di di
a ^ 1
•K
• 4J
ively.
a tral
4-1 U o o di 14H a CO CO 0) i H )H (U
>
CO i H r H
leve!
ater
3
(U 3 4-t (U cn OJ
over Wi
B betW(
CX 13 >% 3 4-t CO O
c M dl
cn 00
+ CO
OH ^ OiH O
« CO r-l 3
CO + <u a OH OH 00
3 ^ H O M
>4H CO CX
<u a 3 O
rH O CO > M
o CO StH 01 4-t 01 O 3 3 rH O; CO
13 >
1 1
1-* eg
«% - f -- t -
A
-»-
33
adjusted yields gave low values with SC 56-14 being the poorest
performing line.
Results obtained for SC 56-14 and NSA 440 are in contrast to
those of TX 2737 which did not have a total photosynthetic area that
differed by LSD from PP + 1 to PP + 3 (Table 7). However, TX 2737 did
have a significant increase in adjusted yield (Table 8) from PP + 1 to
PP + 3. A further observation of the results of Tables 7 and 8
indicates TX 2737 had one of the smallest total leaf areas, but one of
the largest adjusted yields in the PP + 1. This is evidence TX 2737
used the available water in PP + 1 for reproductive growth.
A stable photosynthetic area, such as produced by TX 2737, could
be a selection criteria for a semiarid environment where rainfall is
unpredictable. When water was sufficient, excess leaf area would not
be added, and when water was limited, there would not be excess leaf
area in relation to sink strength.
Dry Weight Means
Means of dry weights generally decreased from PP + 3 to PP + 1 for
all traits (Table 8). Reductions in head dry weight ranged from 10%
(TX 2737) to 53% (TX 7000). Compared over water levels, head dry
weight means separated into two groups with SC 56-14 having the
smallest. Stalk dry matter was reduced from 15% (SC 56-14) to 36% (TX
7000). This is in agreement with results obtained for corn by Boyer
(1976) of 21% reduction. However, results obtained for lines R 9188
and TX 2737 are in disagreement, having increases in PP + 1 of 18% and
2%, respectively. R 9188 may be acting as a perennial by increasing
vegetative growth at the expense of reproductive growth. An inbred
34
line having this characteristic would not be desirable for grain
production if water was limited due to undesirable genotype-
environment interaction.
Inbred lines TX 7000 and SC 170-6-17 had wide variation for stalk
dry weight from PP + 3 to PP + 1; however, a large variation for
adjusted yield relative to other inbreds was not observed (Table 8).
This may be evidence of stalk stored assimilates being translocated to
fill the grain which would allow for adjustment of grain yield in
various environments. Stability over environments could be used in
selection, inbred lines such as TX 7000 and SC 170-6-17 should have a
higher relative grain yield performance in a water limited
environment. Although TX 7078 and TX 2737 were not significantly
different (P = .05) from TX 7000 and SC 170-6-17 (Table 8), there was
wide variation in grain yield between environments (Table 8).
Means of Grain Yield and Related Traits
The values for adjusted yield seem quite low for most inbred
lines in either water level (Table 8). Means for threshing percentage
are also lower than generally expected. Experimental error in
threshing the grain could be the cause of these low values; however,
the thresher was tested prior to threshing the plots.
In both PP + 1 and PP + 3 and over water levels, SC 56-14 had the
least plot head weight and adjusted yield (Table 8). Stalk dry weight
of SC 56-14 was not significantly different from the heaviest at
either water level (Table 8). This would point to assimilates being
in the stalk with potential use for grain fill as reported by Boyer
(1976) and Wardlaw (1967). NSA 440 and TX 2737 had large stalk dry
35
weights in PP + 1 and large grain yields (Table 8) indicating this
mechanism. Low grain yield of SC 56-14 could be explained in part
from it being a nonsenescent type maintaining a large photosynthetic
area at the expense of grain yield. Similar to R 9188, SC 56-14 could
be trying to function like a perennial.
Inbred lines with the largest grain yield over water levels
generally had the lowest moisture percentage and highest threshing
percentage (Table 8). Lines SC 56-14, SC 35-14, and NSA 440 had low
grain yields, high moisture percentages and low threshing percentages,
evidence these were late maturing lines. Under conditions where water
is limited, this late maturing characteristic would be a disadvantage.
The available water would probably be used for vegetative growth or
maintenance while the reproductive system was idle waiting for
adequate moisture for grain fill.
Correlations Between Morphological Traits,
Dry Weights, and Grain Yield
Correlation coefficients were calculated to determine if
meaningful relationships existed among the various morphological
traits, dry weights, and grain yield and related traits. Due to the
possibility that trends may be different with varying water level, the
correlations were calculated for PP + 1, PP + 3 and over water levels.
All data was reported as r-values for simple correlation coefficients.
Plant height had significant positive correlations in PP + 1, pp
+ 3, and over water levels with all morphological traits and dry
weights except head weight and plant weight (Tables 9 & 10). Head
weight was negative and significant in PP + 3 and not significant in
36
1 CO CJ 4-t 0 0
X "H 00 ^
• H J-t d) i H
> N c n V4 13 +
3 ^ C O H CO o
«1 /»!
•H s CO ^
4-t ^
' - I 55 CO 5 o r: •H CX 00 0 *J
^ S O CO
-fi 'TJ a . Ci-^ 0) o >-• S CX
3 13 O 3
CO CO 4J /-N X r H 00 •H + 0) 5 d , . ( ^ > ^ s ^ M
" ^ (U
c -p o 3 CO 5 0
^ ^ ^ ^
gic
al
tra
pre
pla
nt
o ^ -H ^. o ^
^ 3 J H -^ O ^
s § 14H O
o ii 00 CO
c 'H o di •H C 4 J - H
CO ' - • r H di 1 3 M <U M U O X o c •H
. M ON O
(4H (U
r H .O CO H
. / -N O 00 ON r-l
< ^ CO
r H <U > 01
r-i
3 O
•H 4-1
4J • u i . £ P 00 CO'H
r H OJ O H : ?
4-t
<4H 00 CO'H (U o;
h J I S
4-1 ^ J = t H 0 0 C O - H 4 J di
co:3
4-1 1 3 J = CO 0 0 di-H
X di 13
1 o 4-t O O - H
X u i O H O; CO
X di r H 4-t J H
CO 3 < ; 4J >% O CO H
r H < 4 H CO CO CO 0 ) 4-1 OJ VH
Oi_J<5 H
u CO 0 ) CU
^ * 4 H > a o CO 3 OJ
Z H J
rH O CO 3 0) 3 JH
1 3 < : 0 )
O H
OJ rHX O 4J 3 00 3 3
n g OJ
OJ J O H
•K 1 •K -K C N C N r - H i n • > * r H 1
O O
« 1 •K -K <JNO C J N f ^ C g r H
O O
•K -K •K •)( c n < -moo S t C N
O O
•K •K
m m >3-CjN r H CN
o o 1
* -K •K -K c M m c N m ^ e g
O O
•X -K •K -K O N O O s t «3-CsJ
O O
•K -K •K * or-* O N m C M - ^
. . O O
•K -tc •K -K Q o m S t S t
>^m o o
+-- 1 - 4 -•K -te -K -K m m cnoo - ^ m
o o
4-1 4 - t x : 3 00 CO^H
r-i di
O H S
•K 1 * 1
S t r H 1 O O ! r-icn 1
o o 1 1 1 1
•K •K
s t m 1 r ^ v o O C N
o o 1 1 1
•K m r H o m O r H
o o 1 1
•JC - K * * 0 0 - s t s O O
cnso o o 1 1
•K O N c n
cnoo r-lr-4
O O 1 1
•K •K * SOON s O O r H C M
o o 1 1
•K r ^ O N p > . o r H C M
. . o o
•K -K •K -IC
1 CNCM 1 r -cn
CJNCJN
C 5 C 5
1 OJ 1 rH 1 c j j : 1 3 4 J 1 3 00 1 13 3 1 OJ OJ 1 O H H J
s O P > . 1 m s t 1 O r H 1
O O 1 1 1 1
cnr -C n r H 1
o ^ o o 1 1 1
O r H c n CN
o o o o
1
* -K •K -K C n r H r H m
c n ^ o o 1 1
r>.oo «*cn O O
o o 1 1
m m P ^ s O
o o o o 1 1
•K r H O CTNCN r H r H
• . O O
1 OJ 1 r-i
1 a 1 3 1 3 CO 1 13 o; 1 0) u 1 O H < :
•K -K 1 •K -K 1 r H v d - 1 C N O O 1 S t C M 1
O O 1
•K -K 1 •JC - K 1
cncn 1 O O O 1 S t C N
o o 1
•K •K •K -JC m r ^ O O O ^a-st
o o
•K cnm r H P ^ r H r H
O O 1 1
•K -K •JC - K ONi—t
cnso m ^
o o
•K -K •K -K cnr^ cnm m s t o o
1 I4H 1 O
1 U CO 1 OJ OJ 1 ijQ >
1 a n) 1 3 OJ 1 Z H J
•JC •JC 1 •JC •»( O O r H
p^-a- 1 p^oo
o o
•K * •JC * C N P ^ C M - ^ 1 f ^ O O
o o
•JC • K •JC - K cncn cncn 1 r^oo
o o
•K -K •K •JC cnm cnst cnst
o o
•K •K •K •K <JNC3N CJNCJN CJNCJN
O O
t '4H t CO 1 OJ 1 X
1 r-i 1 CO CO 1 4-t OJ
1 o u 1 H < :
•K -K 1 •K •JC 1 0 0 0 0 1 p^cn 1 P^OO 1
O O 1
•JC • * 1 •Jt -JC 1
C N s t 1 C N S t 1 r^oo 1
O O 1
•K * •K * m s t cncn 1 P ^ O O
o o
•JC •K •K -JC m e n 1 cNcn 1 c n s t
O O
oto-
c A
rea
1 X-H 1 CU 4J 1 OJ 1 HX 1 CO i J 1 4-t 3 1 O > , 1 H CO
•JC -IC 1 •JC •je 1
(JN^d-0 0 0 0 1 S t s O
o o 1
•JC •K 1 •K -K 1 - ^ c n 1 ONON 1 C N m 1
o o 1
•JC •JC 1 •JC - K CMi-l 1 OCJN c n s t 1
O O 1
4-t X
1 T3 00 1 CO-H 1 OJ OJ
1 x:s
• K •JC 1 •JC •JC e g o 1 S t s O 1 CJNCJN
O O 1
•JC •K 1 •JC • * 1 P^^sO 1 m O N 1
r^oo 1 O O 1
4-t
1 ^x 1 H 0 0 1 C O ' H 1 4.t OJ
1 c o : 2
• K -JC •JC -JC ^ 0 0 O N m 0 0 CJN
o o
• u 1 X 1 "H 00 1 CO'H 1 0) OJ 1 x:s
>N 4J •H >
O OJ CX CO OJ
u
X CO
X o u a
OJ
> OJ
o o • p
3 CO
m o
4-1 CO
3 CO O
3 00 •H
CO
I •JC •JC
OJ
> •H 4-1 CJ OJ CU CO OJ u
cn
+ OH O)
OH
OH
U O
OJ 3
r-i CO >
CO OJ 4J
o 3 OJ
13
37
weights
>% u
T3
ts and
•H CO U
4-t
r H CO CJ
•H
00
o r H
O X
morp
3 O
CO
4-t X 00
• H 0)
>» u
13
TS 3 CO
CO . 4-1 / - s
• H O CO 0 0 JH CJN 4J r H
V ^
r H CO CO O r H
• H OJ
0 0 > O OJ
X rH
o X u CX OJ Ul 4-t
O CO
a > 14H JH O OJ
> CO o 3 O CO
• H OJ 4-1 3 CO ' H
r H rH OJ
Corr
inbred
• O J-" r H O
14H OJ
rH X CO
H
4J
3 00 CO'H
r H OJ
O H 3
4-t
J= 14H 00 CO'H OJ OJ
4J
Stal
Welg
4-1 1 3 JS
CO 00
OJ 'H X OJ
1
o •u u O ' H
J= 4-1
OH OJ CO X OJ
r H 4J JH CO 3 < •w >. O CO
H
r H l 4 H CO CO CO OJ
4-1 OJ J H
O K J < : H
M CO 0) OJ
X ^ >
a O CO 3 OJ
Z H J
OJ r H a CO 3 OJ
3 H
-a< OJ
OH
0) r H J = O 4-t
3 00 3 3
13 OJ
0 ) r J OH
•JC •JC ON
o •
o
•K •K <JN
0.36
•K •K
.406
o
•K •K
O
m
0.2
•K •K
r>. 0 0 -3-
• O
•K •K eg
r St
• o
•K 1 • K 1
cn 1 m 1 CM 1
. j
O 1
•JC 1 •K 1
P>' 1 P^ 1
m 1 • 1
O 1
•K 1 •K 1
O 1 0 0 1
m 1 • 1
O 1
4J 1 4-iX 1 3 00 1 CO'H 1
H OJ 1 OH X 1
1 S t 1 0 0 1 O 1 •
1 o 1 1 1 1
1 0 0
-0.05
.001
1 o
1 •K 1 -K 1 ON 1 ON
-0.2
1 CJN
1 o 1 o 1 • o
1
m cn o
• o 1 1
•K 1 0 0 1
cn 1 r H 1
. 1
O 1
* 1 •JC 1 CM 1
m 1 ON 1
• 1
O 1
OJ 1 r-i 1 ^ X 1 3 4-i 1
3 00 1 T3 3 1 OJ (U 1
P4X 1
1 ON 1 r-4 1 0 1 •
1 0
1 m
0.03
.098
1 0
1 < * 1 ON
-0.1
1 m 1 0 1 r-4 1 .
1 0
0 0 r>v
0 •
0
•K 1
P^ 1 S t 1 r H 1
a 1
0 1
di 1 rH 1
U 1 3 1 3 CO 1
13 OJ 1 OJ U 1
o.<«: 1
1 •J* 1 •K 1 .JC 1 -JC 1 •K 1 •JC
1 m 1 0 0 1 m 1 cn 1 cn 1 cn 1 c n 1 0 0 1 0 0 1 • 1 • 1 .
1 0 1 0 1 0
1 * 1 -K 1 •JC 1 -K 1 •JC 1 •IC 1 0 0 1 sO 1 i n
0.33
0.80
0.80.
1 -JC 1 • * 1 -JC 1 •K 1 -JC 1 «
.434
.803
.804'
j 0 1 0 1 0
1 1 •K 1 •K ! 1 JC 1 -JC 1 ON 1 0 1 > ^ 1 rH 1 <-~) 1 OS
-0.1
0.51
0.4<
1 •K 1 •K 1 1 •JC 1 •K 1 1 ^ 1 ON 1 1 m I <jN 1 1 - ^ 1 CJN 1 1 . 1 . 1
0 1 0 1
CN 1 1 m 1 1 S t 1 1
• 1 1
0 1 1
1 1 CO 1 1 1 OJ 1 1 1 1 VH 1 1 1 o < 1 1 <4H 1 4-t 1
<4H 1 CO 1 0 U 1 0 1 OJ 1 X H 1
\ X 1 OH -U 1 V-l CO 1 1 01 1 OJ OJ 1 r H 1 HJZ 1
-O > 1 CO CO 1 CO 4-) 1
a CO 1 4-t OJ 1 4-t 3 1 3 OJ 1 0 JH 1 0 >%l
Z P - J 1 i H < 1 H CO 1
1 •JC 1 •JC
1 0 1 so 1 s o 1 •
1 0
1 •K 1 •JC 1 U3
0.52(
1 •K 1 Je
.470'
1 0
4-t 1 X 1
13 00 1 CO'H 1
OJ OJ 1
x:s 1
1 •K 1 • K 1 cn 1 m 1 ON 1 •
1 0
1 ^ I -K 1 . ^
0.84]
.
4-t 1 ^ X 1 <H 00 1 CO'H 1 4-t OJ 1
C 0 3 1
1 •K 1 -JC 1 CN
1 cn 1 ON 1 •
1 0
4_|
JZ 14H 0 0 CO'H
OJ OJ
r J S
vely.
' H
respect
4J
• H
r-i
robabJ
Cl.
>4H 0
level
r H 0
• 0
and
m 0
• 0
4-t
CO
Lgnificant
CO
1 1
•t(
•JC
•JC
38
PP + 1, and plant weight was not significant in PP + 3 when correlated
with plant height. Over water levels, peduncle length resulted in the
highest positive significant correlation (0.577) (Table 10) with plant
height as would be expected since internode length is directly related
to plant height, being measurements of the same overall genetic
expression.
An observation of the means (Tables 7 and 8) indicates wide
variation of all inbred lines for plant height and head dry weight
except R 9188 and TX 2737 which remained essentially constant over
water levels (LSD not significant). All morphological traits gave
significant negative correlations with grain yield in PP + 1 and PP +
3 except head dry weight which gave highly significant positive
correlations for both plot head weight and adjusted yield (Table 9).
However, large variations in grain yield (1000 kg/ha) between
environments for R 9188 and TX 2737 may 'be evidence these are early
lines able to use available water for grain yield (Table 11).
Correlation of peduncle length with morphological traits in PP +
1 and PP + 3 were negative when significant, except number of leaves
in PP + 3 (Table 9), as were r-values for grain yield traits (Table
11). Over water levels, a positive highly significant (P = .01)
correlation was observed between head dry weight and peduncle length.
This relationship would be expected since peduncle length is related
to plant height, and plant height and head dry weight were positively
correlated (Table 10).
No significant positive correlation of peduncle length with grain
yield was observed (Tables 11 & 12), unlike results reported for wheat
w 39
Table 11. Correlations of grain yield and related traits on morphological traits and dry weights of inbred lines grown under preplant plus one (PP + 1) and preplant plus three (PP + 3 ) irrigation levels (1980).
PLOT
Head Weight
Adjusted Yield
Moisture Percentage
Plant Dry Weight
-0.044 -0.082
-0.152* -0.195*
0.330** 0.053
Threshing Percentage
Plant Height
Peduncle Length
Peduncle Area
Number of Leaves
Total Leaf Area
Total Photosynthetic Area
Head Dry Weight
Stalk Dry Weight
Leaf Dry Weight
0.002 t 0.218**tt
-0.055 -0.372**
-0.036 -0.209*
-0.060 -0.243**
0.041 -0.232**
0.040 -0.238**
0.324** 0.291**
-0.151* -0.214**
-0.048 -0.075
-0.079 -0.339**
-0.049 -0.444**
-0.038 -0.369**
-0.168* -0.270**
-0.062 -0.389**
-0.064 -0.400**
0.277** 0.210**
-0.258** -0.315**
-0.140 -0.192*
0.324** 0.423**
0.167* 0.515**
0.155* 0.622**
0.486** 0.497**
0.291** 0.203**
0.296** 0.221**
-0.232** ^0.320**
0.420** 0.186*
0.330** 0.051
-0.278** -0.023
-0.023 0.197*
-0.043 -0.326**
-0.310** -0.084
-0.278** -0.356**
-0.280** -0.366**
0.100 -0.106
-0.385** -0.234**
-0.267** -0.234**
-0.311** -0.231**
*, ** - significant at 0.05 and 0.01 probability level, respectively. t, ft - denotes value for PP + 1 and PP + 3, respectively.
40
Table 12. Correlations of grain yield and related traits on morphological traits and dry weights for inbred lines over water levels (1980).
PLOT PLANT
Head Weight
Adjusted Yield
Moisture Percentage
Threshing Percentage
Plant Height
Peduncle Length
Peduncle Area
Number of Leaves
Total Leaf Area
Total Photosynthetic Area
Head Dry Weight
Stalk Dry Weight
Leaf Dry Weight
Plant Dry Weight
0.521**
0.095
0.171**
-0.083
0.200**
0.204**
0.492**
0.060
0.181**
0.200**
0.296**
-0.029
0.010
-0.167
0.009
0.010
0.401**
-0.104
0.024
0.036
-0.310**
0.028
0.056
0.365**
-0.068
-0.067
-0.447**
0.075
-0.033
-0.065
-0.617**
-0.301**
-0.365**
-0.183**
-0.464**
-0.473**
-0.269**
-0.387**
-0.377**
-0.406**
** - significant at 0.01 probability level
41
by Briggs and Aytenfisu (1980). Correlations between peduncle area
and morphological traits and dry weights followed the same patterns as
peduncle length except for a significant negative correlation with
head dry weight of -0.194 in PP + 1 (Table 10). No positive
correlation between peduncle area and leaf area or photosynthetic area
indicates that size of peduncle area in relation to photosynthetic
area was either too small to have an effect or leaf area and peduncle
area develop independently.
Peduncle length and plant height are the result of internode
expansion. The positive significant association (Tables 9 & 10) of
peduncle length with plant height indicates taller inbreds had longer
peduncles. However, an observation of the means (Table 7) reveals
that even though SC 170-6-17 had large variations for height from PP +
1 and PP + 3 of about 20 cm, peduncle length remained essentially
constant as did peduncle length of TX 7078 and NSA 440. Selection of
types not varying for peduncle length in various environments would
result in a genotype with a good combine harvest characteristic.
Correlation coefficients for number of leaves were positive and
highly significant (P = .01) with all dry weights in PP + 1 and PP + 3
(Table 9) and over water levels (Table 10) except head dry weight
being negative when significant. Data indicates as leaf number
increased dry weight increases as expected since number of leaves is
directly related to leaf weight and so to plant weight. Negative
correlation between head dry weight and number of leaves could be due
to inbreds SC 56-14, SC 35-14 and R 9188 having small head dry weights
and large leaf numbers in PP + 1 and PP + 3. Correlations between
42
number of leaves and grain yield were negative when significant for PP
+ 1, PP + 3, and over water levels (Tables 11 & 12). This type of
association with head dry weight and grain yield could relate to
optimal vegetative production for maximum grain yield under water
stress referred to by Fisher and Kohn (1966b). SC 56-14, SC 35-14,
and R 9188 may have put on excess leaf area using water needed later
t-
for grain filling. The excess leaf area could be due to June 30
irrigation near the time of panicle initiation resulting in more
leaves being initiated or allowing leaves already initiated, but not
mature, to increase in size.
Correlations between leaf area and total photosynthetic area with
dry weights in PP + 1 and PP + 3 (Table 9) and over water levels (Table
10) were all positive and highly significant (P = -01). Leaf number,
leaf area, and total photosynthetic area are directly related being
similar measurements of the same genetic expression. Correlations of
these three traits with dry weights followed the same pattern, except
for a significant negative correlation in PP + 1 between leaf number
and head dry weight.
Leaf area and photosynthetic area correlations between grain
yield and associated traits were negative when significant in PP + 1
and PP + 3 (Table 11) and were not significant over water levels
(Table 12). This contradicts results reported by Voldeng and Simpson
(1967) and Simpson (1968) of positive correlations between grain yield
of wheat and photosynthetic area. Stickler and Pauli (1961) reported
increased relative yield per unit leaf area when leaves were removed,
implying that less leaf area may give a compensation effect allowing
43
assimilates that may otherwise be diverted to leaf area production to
be used for grain yield.
From the photosynthetic area data, conclusions can be made that R
9188 and TX 2737 were the most consistent (LSD not significant), each
varying only slightly between water levels. No significant positive
correlation between photosynthetic area and grain yield was observed
(Tables 11 & 12), contrary to results obtained by Leeton (1978). An
observation of the means (Table 7) indicates TX 2737 and R 9188 had
consistent photosynthetic areas, but wide variation (LSD significant)
in grain yield between water levels. In contrast, TX 7000 and SC 170-
6-17 had wide variation (LSD significant) in photosynthetic area, but
grain yields between treatments (LSD for TX 7000 not significant, but
SC 170-6-17 significant) were not as variable as other inbred lines.
Inbreds TX 7000 and SC 170-6-17, added extra leaf area with additional
water. However, these two lines not having a corresponding increase
in grain yield, may be an indication of inefficient partitioning.
This relates to the optimal amount of vegetative growth produced in
relation to grain yield referred to by Fisher and Kohn (1966b).
Over water levels correlations were positive and highly
significant (P = -01) between plant height and photosynthetic area
(Table 10), evidence that the taller lines produced more leaves and
stalk, and larger peduncles at maturity. This indicates that
selection for any one of these traits would have an effect on other
traits for these inbred lines.
Correlations between plant dry weights were all highly signifi
cant and positive for PP + 1, PP + 3, and over water levels as expected
44
since these similar measurements of the same genetic system. Over
water levels correlations of head dry weight, leaf dry weight and
plant dry weight with plot head weight were positive and highly
significant (P = .01) (Table 12). Correlations between dry weights
and plot head weight and adjusted yield were negative when significant
in PP + 1 and PP + 3 (Table 11). Over water levels head dry weight,
leaf dry weight and plant dry weight gave positive, highly significant
(P = .01) correlations with plot head weight (Table 12). Only head
dry weight gave positive significant correlations with adjusted yield
(Tables 11 & 12). The highly significant positive correlation between
head dry weight at bloom and plot head weight can be explained as
being due to florets produced in the panicle leading to final grain
yield.
Data for means of dry weights and adjusted yield (Table 8)
indicate that genotype by water level interactions resulted in wide
variation between treatments. TX 7000 had a decrease in head weight
of about 6 grams from PP + 3 to PP + 1, but only a 500 kg/ha decrease
in grain yield (Table 8). This contrasts with R 9188 and TX 2737
which had essentially the same head dry weight with either water
level, but grain yield decreases of over 1000 kg/ha.
Stalk dry weight was reduced for TX 7000 and SC 170-6-17 while
other genotypes did not decrease as greatly from PP + 3 to PP + 1. The
observation of Wardlaw (1967) and Boyer (1976) that assimilates are
translocated from the stalk to fill the grain could explain part of
the grain yield results obtained for TX 7000 and SC 170-6-17.
45
NSA 440 also had a large decrease in head dry weight from PP + 3
to PP + 1, and although grain yield was only decreased 300 kg/ha, rank
in relation to other lines for grain yield was low (Table 8).
Head dry weight at bloom was positively correlated with grain
yield (Tables 11 & 12). An observation of the data indicates that
although TX 7000 and SC 170-6-17 had large decreases in head dry
weight, the reductions in grain yield were not as substantial as the
reduction for R 9188 and TX 2737. NSA 440 ranked second in PP + 1 for
head dry weight, but sixth for adjusted yield, indicating an inability
to fill the grain.
Head dry weight over water levels (Table 8) for SC 170-6-17 was
lower than TX 2737, TX 7078, and TX 7000, but adjusted yields of these
lines were not significantly different. In the PP + 1, head dry
weights for TX 2737 and TX 7078 were significantly different from SC
170-6-17 and TX 7000, but adjusted yield was not significant. In PP +
3, head dry weight and adjusted yield for the four lines were not
significantly different.
The means for adjusted yield of TX 7000 and SC 170-6-17 were more
consistent over both water levels (Table 8). If stability of yield
over a range of environments was desired, these would be the types of
lines selected for use in a breeding program due to their ability to
produce grain yield when water is limiting.
Data for plant dry weight (Table 8) indicates TX 7000 and SC 170-
6-17 had large variation in dry matter production between water levels
at bloom while R 9188 and TX 2737 remained essentially the same in
both treatments. Adjusted yield of TX 7000 and SC 170-6-17, though
46
not significantly different, exceeded TX 7078 by 400 kg/ha and 240
kg/ha, respectively. Evidence is provided that TX 7000 and SC 170-6-
17 were able to use the available moisture in PP + 1 for grain fill
rather than vegetative growth.
Plant dry weight of inbred lines R 9188 and TX 2737 remained
essentially the same in either environment (Table 8). However, wide
variations in grain yield indicate an interaction of water level with
genotype for grain yield, but not vegetative growth. This could be
due to early maturity or extensive growth of the root system.
Correlations between plot head weight, grain weight, and adjusted
yield were highly significant and positive in PP + 1, PP + 3, and over
water levels (Table 13) as would be expected since these are directly
related. However, correlations between these grain yield traits and
moisture percentage were significant and negative in PP + 1 and PP +
3, and over water levels. Threshing percentage had a highly
significant (P = .01) negative correlation with plot head weight over
water levels (Table 13). This indicates excess nonseed portions were
produced in relation to grain.
An observation of the means indicates that inbreds with the
largest grain yield had the lowest moisture percentage and highest
threshing percentage (Table 8). Lines SC 56-14, SC 35-14, and NSA 440
had low grain yields, high moisture percentage, and low threshing
percentage, evidence that late maturity could account for some of the
low yielding potential for these inbred lines.
47
Table 13. Correlations between grain yield and related traits for inbred lines grown under preplant plus one (PP +1) and preplant plus three (PP + 3) irrigation levels and over water levels (1980).
Plot Head Weight
Adjusted Yield
0.958**t 0.844**tt 0.900**^
Moisture Percentage
-0.419** -0.195* -0.618**
Threshing Percentage
0.387** -0.024 -0.375**
Plot Adjusted Yield -0.546** -0.323** -0.627**
0.614** -0.268** 0.035
Moisture Percentage -0.634** 0.504** 0.098
* * _
t, tt. significant at 0.05 and 0.01 probability level, respectively. ^ - denotes value for PP + 1, PP + 3, and over water levels,
respectively.
CHAPTER V
SUMMARY AND CONCLUSIONS
The major objectives of this study were to (1) determine what
genotypic variation existed among eight sorghum inbred lines, (2)
determine genotype by environment interaction, (3) determine if a
relationship existed between leaf area and related morphological
traits and grain yield, and (4) identify inbred lines suitable for
further genetic study.
Significant genotypic differences were consistently detected at
the 0.01 level of probability for all morphological traits and grain
yield, leading to the conclusion that variation exists among the eight
genotypes for traits tested. Water level by genotype interaction
resulted in significant differences for all morphological traits
excluding number of leaves. This observation is contradictory to
results obtained by others of decreased leaf numbers with water
stress. The lack of variation in number of leaves observed in this
study could be explained in part as resulting from the inbred lines
growing in comparable macroenvironments during the leaf initiation
period. More data should be obtained to determine if this lack of
variation is due to genetic effects or if the environmental effects of
this study were not effective in attaining a response.
Water level had a modifying effect on photosynthetic area,
causing significant increases from PP + 1 to PP + 3. TX 7000 and SC
170-6-17 added additional leaf area with additional water, but there
48
49
was little increase In grain yield observed indicating inefficient
partitioning of assimilates for grain production.
Evidence of differential water use was obtained from the
significant genotype by water level interactions of morphological
traits measured as dry weights. These results suggest certain inbreds
perform better under higher water levels and others under lower water
levels. Inbred lines should be evaluated to determine such responses
to water levels since, depending upon correlations with grain yield,
particular lines may be better suited to a specific water level, and
provide superior segregates for such traits in a breeding program.
Significant reductions in the stalk dry weights of TX 7000 and SC
170-6-17 and a small decrease in grain yield relative to other inbred
lines were observed. These results may imply utilization of stalk
stored assimilates in these two lines. However, no positive
significant correlation of stalk dry weight at bloom with grain yield
was observed. If stalk stored assimilates are important for grain
filling in sorghum, evaluations of this trait are needed. The ability
of an inbred to use stalk stored assimilates for grain yield during
periods of water stress would be an important factor from a breeding
standpoint.
Genetic differences were detected among inbred lines for grain
yield. Genotype by water level interaction was not significant for
grain yield. However, the interaction gave significant differences
for unthreshed head weight. These results indicate the relative
position of an inbred line did not change over water levels, and
additional water was used for vegetative, not reproductive growth.
50
This could be an indication of inefficient partitioning. Some of the
variation in performance among inbreds for grain yield could be
explained by early maturity and leaf senescence. While these
characteristics are desirable in some environments, they are not
always advantageous in all environments. The use of these character
istics by the breeder is dependent on the type of environment he is
concerned with in his breeding program.
Most positive significant correlations obtained were attributable
to measurement of the same overall genetic system. Significant
negative correlations between photosynthetic area or leaf area and
grain yield suggest less relative leaf area may be beneficial when
water is limiting. Head dry weight at bloom was the only
morphological characteristic exhibiting a positive significant rela
tionship with grain yield which could merit further evaluation to
determine usefulness in screening of inbred lines.
APPENDIX
1. Precipitation after June 4 for 1980 growing season and 1980 totals to date recorded at Texas Tech University Farm.
51
52
Appendix Table 1. Precipitation after June 4 for 1980 growing season and 1980 totals to date recorded at Texas Tech University Farm.
Precipitation Total to Date Total for Year
Date (mm) (mm) (mm)
June 8 5.1 5.1 90.6
June 11 23.3 28.4 113.9
July 27 14.4 42.8 128.3
August 4 26.9 69.7 155.2
August 14 16.2 85.9 171.4
August 15 7.6 93.5 179.0
September 1 2.0 95.5 181.0
September 9 7.1 102.6 188.1
September 10 15.2 107.8 203.3
REFERENCES CITED
1. Acevedo, E., T. C. Hsiao, and D. W. Henderson. 1971. Immediate and subsequent growth responses of maize leaves to changes in water status. Plant Physiol. 48:631-636.
2. Bennett, J. M. 1975. The effect of light and water stress on yield and yield components of grain sorghum. M.S. Thesis, Texas Tech University.
3. Birecka, H., J. Skupinska, and I. Bernstein. 1967. Photosynthetic activity before and after heading in spring barley. Acta. Soc. Bot. Pol. 36(2):386-409- (English summary in Biol. Abstr..Vol. 49, No. 36758).
4. Blum, A. 1974. Genotypic responses to sorghum to drought stress. I. Response to soil moisture stress. Crop Science 14:361-364.
5. Boyer, J. S. 1976. Photosynthesis at low water potentials. Phil. Trans. R. Soc. Lond. B. 273:501-512.
6. Briggs, K. G. and A. Aytenfisu. 1980. Relationship between morphological characters above the flag leaf node and grain yield in spring wheats. Crop Science 20:350-354.
7. Campbell, C. M. 1964. Influence of seed formation of corn on accumulation of vegetative dry matter and stalk strength. Crop Science 4:31-34.
8. Clark, L. E. 1970. Embryonic leaf number in sorghum. Crop Science 10:307-309.
9. Clarke, L. E. and D. Pietsch. 1980. Grain sorghum yield performance, Chillicothe—1980. TAES Bulletin PR-3730, March, 1981.
10. Clegg, M. D. 1969. Row spacing, plant population and light interception as they influence sorghum yield. Ln Proceedings of the 24th annual corn and sorghum research conference.
11. Daynard, T. B., J. W. Tanner, and D. J. Hume. 1969. Contribution of stalk soluble carbohydrates to grain yield in corn (Zea mays L.). Crop Science 9:831-834.
12. Eastin, J. D. and C. Y. Sullivan. 1969- Carbon dioxide exchange in compact and semi-open sorghum inflorescences. Crop Science 9:165-166.
13. Elk, Kalyu, J. J. Hanway. 1966. Leaf area, its relation to yield of corn grain. Ag. J. 58:16-18.
53
54
14. El-Sharkaway, M. A. and J. D. Hesketh. 1964. Effects of temperature and water deficit on leaf photosynthetic rates of different species. Crop Science 4:514-518.
15. Fischer, K. S. and G. L. Wilson. 1971. Studies of grain production in Sorghum vulgare. I. The contribution of preflowering photosynthesis to grain yield. Aust. J. Agric. Res. 22:33-37.
16. Fischer, K. S., G. L. Wilson and I. Duthie. 1976. Studies of grain production in Sorghum bicolor (L. Moench). VII. Contribution of plant parts to canopy photosynthesis and grain yield in field situations. Aust. J. Agric. Res. 27:235-242.
17. Fisher, R. A. and G. D. Kohn. 1966a. The relationship between evapotranspiration and growth in the wheat crop. Aust. J. Agric. Res. 17:255-267.
18. Fisher, R. A. and G. D. Kohn. 1966b. The relationship of grain yield to vegetative growth and post-flowering leaf area in the wheat crop under conditions of limited soil moisture. Aust. J. Agric. Res. 17:281-295.
19. Graham, D. and K. J. Lessman. 1966. Effect of height on yield and yield components of two isogenic lines of Sorghum vulgare Pers. Crop Science 6:372-374.
20. Hadley, H. H. 1957. An analysis of variation in height in sorghum. Agronomy Journal 49:144-147.
21. Hadley, J., J. E. Freeman, and E. Q. Javier. 1965. Effects of height mutations in grain yield in sorghum. Crop Science 5:11-14.
22. Herbert, S. W., S. Fukai, and G. L. Wilson. 1982. Plant characteristics associated with high grain yield under high and low moisture availability. Sorghum Newsletter 25:1.
23. Keim, D. L. and W. E. Kronstad. 1981. Drought response of winter wheat cultivars grown under field stress conditions. Crop Science 21:11-15.
24. Lawes, D. A. and K. J. Treharne. 1971. Variation in photosynthetic activity in cereals and its implication in a plant breeding programme. I. Variation in seedling leaves and flag leaves. Euphytica 20:86-92.
25. Leeton B. S. 1978. Photosynthetic variation in sorghum genotypes. M.S. Thesis, Texas Tech University.
55
26. Major, D. J. and W. M. Haman. 1981. Comparison of sorghum with wheat and barley grown on dryland. Can. J. Plant Sci. 61:37-43.
27. McKree, K. J. and S. D. Davis. 1974. Effect of water stress and temperature on leaf size and number of epidermal cells in grain sorghum. Crop Science 14:751-755.
28. Moss, D. N. and R. B. Musgrave. 1971. Photosynthesis and crop production. Advances in Agronomy 23:317-336.
29. Pauli, A. W., F. C. Stickler, and J. R. Lawless. 1964. Developmental phases of grain sorghum (Sorghum vulgare Pers.) as influenced by variety, location, and planting date. Crop Science 4:10-13.
30. Porter, H. K., N. Pal, and H. V. Martin. 1950. Physiological studies in plant nutrition. XV. Assimilation of carbon by the ear of barley and its relation to the accumulation of dry matter in the grain. Annals of Bot. Lond. 14:55-68.
31. Quinby, J. R. 1972. Influence of maturity genes on plant growth in sorghum. Crop Science 12:490-492.
32. Quinby, J. R. , J. D. Hesketh, and R. L. Voigt. 1973. Influence of temperature and photoperiod on floral initiation and leaf number in sorghum. Crop Science 13:243-246.
33. Ramos, J. M., L. F. Garcia de Moral, and L. Recalde. 1983. Dry matter and leaf area relationships in winter biology. Ag^ J. 75:308-309.
34. Sanchez-Diaz, M. F. and P. J. Kramer. 1971. Behavior of corn and sorghum under water stress and during recovery. Plant Physiol. 48:613-616.
35. Shertz, K. F. 1970. Single-height-gene effects in doubled haploid sorghum bicolor (L.) Moench. Crop Science 10:531-534.
36. Sieglinger, J. B. 1936. Leaf number of sorghum stalks. Ag. J. 28:636-642.
37. Simpson, G. M. 1968. Association between grain yield per plant and photosynthetic area above the flag leaf node in wheat. Can. J. Plant Sci. 48:253-260.
38. Steel, R. G. D. and J. H. Torrie. 1960. Principles and Procedures of Statistics. McGraw-Hill, New York.
56
39. Stickler, F. C. and A. W. Pauli. 1961. Leaf removal in grain sorghum. I. Effects of certain defoliation treatments on yield and components of yield. Ag. J. 53:99-102.
40. Stickler, F. C., S. Wearden, and A. W. Pauli. 1961. Leaf area determination in grain sorghum. Ag. J. 53:187-188.
41. Stout, D. G., T. Kannangara, and G. M. Simpson. 1978. Drought resistance of Sorghum bicolor. 2. Water stress effects on growth. Can. J. Plant Sci. 58:225-233.
42. Vinall, H. N. and H. R. Reed. 1918. Effect of temperature and other meteorological factors on the growth of sorghums. J. Ag. Res. 13:133-148.
43. Voldeng, H. D. and G. M. Simpson. 1967. The relationship between photosynthetic area and grain yield per plant in wheat. Can. J. Plant Sci. 47:359-365.
44. Walton, P. D. 1969. Inheritance of morphological characters associated with yield in spring wheat. Can. J. Plant Sci. 49:587-596.
45. Wardlaw, I. F. 1967. The effect of water stress on translocation in relation to photosynthesis and growth. I. Effect during grain development in wheat. Aust. J. Biol. Sci. 20:25-39.
46. Wareing, P. F., M. M. Khalifa, and K. J. Treharne. 1968. Rate-limiting processes in photosynthesis at saturating light intensities. Nature 220:453-457.
47. Watson, D. J. 1942. The physiological basis of variation in yield. Advances in Agronomy 4:101-145.
48. Watson, D. J., G. N. Thorne, and S. A. W. French. 1958. Physiological causes of differences in grain yield between varieties of barley. Annals of Botany 22:321-352.
49. Watson, D. J., G. N. Thorne, and S. A. W. French. 1963. Analysis of growth and yield of winter and spring wheats. Annals of Botany 27:1-22.
V