WWWIWIHHWIW\NIHIWHIUIIWIIWHIHHI

   

 

20‘5 6 "l l”? (7 llllclellTIT!lllllillllllllllllll

3 1293 00541 4978

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

LIBRARY
Michigan State
University

 

 

 

This is to certify that the

thesis entitled

Evaluation of the Leafy Characteristics in Maize
(_Ze__a mazs L.)

presented by

Mohammed Barre Ahned ~

has been accepted towards fulfillment
of the requirements for

”9???ng

Major professor *

 

 

Crop & Soil Sciences

 

Date 1/25/88

 

0-7639 MS U is an Affirmative Action/Equal Opportunity Institution

/
J _ _, ._ “”7, ,V__r

r" c .. H3"? ‘*
I ' 3:2 a
l .» . _
I n
3 I 5
1 I.
l fit: 0 ‘i mafia
) .
«a 4’4
‘ we.
“(a 9}. _
'3 L;
L «1.1 .
; '2»
: *=o

 

 

 

MSU

LIBRARIES
—:—.

 

 

RETURNING MATERIALS:
Place in book drop to
remove this checkout frow
your record. FINES wil?
be charged if book is
returned after the date
stamped below.

 

 

 

 

JUN I 31% ‘,

liiiwifi
'1' -

 

 

AGRONOMIC EVALUATION OF THE LEAFY (LEY) TRAIT

IN MAIZE (Zea maysL.)

by

Mohamed Barre Ahmed

A THESIS
submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of
MASTER OF SCIENCE

Department of crop and Soil Sciences

1987

ABSTRACT
AGRONOMIC EVALUATION OF THE LEAFY ( LE1) TRAIT
IN MAIZE (fig; gays L.)
by

Mohamed Barre Ahmed

Enhancement of assimilate supply through increase of
leaf number at the top of the canopy may improve the grain
yield in maize. Michigan State University received Lfy
germplasm from Dr. D. L. Shaver who has a U.S. patent for
use of the leafy Lfy, trait in maize production. Sixty-four
experimental Lfy hybrids were compared with eight commercial
non leafy hybrids in replicated yield trials in order to
determine their agronomic potential. Two experiments were
conducted in Cass and Saginaw Counties, Michigan in 1986.
Several agronomic characteristics including leaf number above
the primary ear were recorded. Leaf shading was calculated
as the distance between two leaves on the same side of the
stalk. Correlation analyses were used to determine the
interrelationship among all agronomic characteristics for
each location and over locations. Results suggested that the
four "best" Lfy hybrids were at least equal to the best two
normal hybrids and significantly better than five of the best
commercial check hybrids. The Lfy hybrids were generally later
in maturity and taller than non leafy hybrids. Plant height
and shading effect were the most influential characteristics

for grain yield as indicated by multiple regression analyses.

Dedicated to my Parents,
Barre Ahmed and Kutubei Mohamud
who provided the means and environment
to pursue my life’s goals, with gratitude,

admiration, and love.

iii

ACKNOWLEDGMENTS

I wish to express my sincerest appreciation to my major
professor Dr. E. H. Everson, for his unfailing encouragement,
enthusiasm and advice during my graduate study.

My profound gratitudes also belongs to Dr. E. C. Rossman
under whose inspiration, guidance, and counsel this study was
under taken. I have learned a great deal of knowledge from
his experience which can not be found in any text book.

Grateful thanks is extended to Dr. L. C. Ewart for
serving me as a member of my guidance committee.

Special thanks is given to Keith Dysinger and Marvin
Chamberlin for their gracious technical help in carrying
out this research.

Professor C. Harrison provided extremely helpful for
editing the draft of my thesis, and I am deeply indebted.

The financial support of the Somali government and Safgrad
organization is herewith gratefully acknowledged.

Finally, my deep love and appreciation to my family, whom,
have accepted to endure a long absence of myself from home

country during my study.

iv

TABLE OF CONTENTS

Page

LIST OF TABLES ..........................................vi
LIST OF FIGURES .......................................viii
INTRODUCTION .............................................1
LITERATURE REVIEW ........................................3
Canopy Structure .............................. ...... 3
Grain filling Period ................................6
Partition of Assimilates ...........................10
Environmental Factors Affecting Leaf Number ........12
Genetic Improvement of Leaf Number ................. 15
MATERIALS AND METHODS .. ........ .. .......... . ..... .......18
RESULTS .................. ................... . ....... ....25
DISCUSSION ........... ......................... . ....... ..40
CONCLUSIONS .................. ............... ............48

BIBLIOGRAPHY OOOOOOOOOOOOOOO 000000000000 00...... ........ .49

LIST OF TABLES

Page

Table 1. Pedigrees of Leafy and non Leafy hybrids ....... 21
Table 2. Form of analysis of variance used to estimate
component of variance for locations and hybrids .........23
Table 3. Means of nine morphological and physiological
characteristics averaged over locations ................30
Table 4. Mean values for nine morphological and physiological
characteristics of hybrids, grown in Cass County ........31
Table 5. Mean values for nine morphological and physiological
characteristics of hybrids, grown in Saginaw County .....33
Table 6. Mean values for nine morphological and physiological
characteristics of hybrids combined over locations ......35
Table 7. Comparison of 4 best L151 hybrids with 3 best
Commercial check hybrids ................................37
Table 8. Comparison of 4 best L21 hybrids with 5 Commercial
check hybrids ..........................................38
Table 9. Variety correlation coefficients among characters
ovem' locations ..........................................39
Table 10. Mean squares from analysis of variance of data
collected at Cass County ................................57
Table 11. Mean squares from analysis of variance of data

collected at Saginaw County ........ ....... . .......... ...58

vi

Table 12. Mean squares from combined analysis of variance

for various characteristics .............................59
Table 13. Correlation coefficient among characters at Cass
County ..................................................60
Table 14. Correlation coefficient among characters at Saginaw

county 0.0......OOOOOOOOOOOOOOOOOOO0.0.0.000000000000000061

LIST OF FIGURES

Figure 1. Plant measurements and the calculation of shading
effect ..................................................24
Figure 2. Relationship between shading effect (cm)and grain
yield tons/ha ...........................................45
Figure 3. Relationship between moisture percentage (%) and
leaf number above the ear 45
Figure 4. Relationship between plant height (cm) and leaf
number above the ear ....................................45
Figure 5. Relationship between leaf number above the ear
and stalk lodging (%) ...................................45
Figure 6. Relationship between leaf number above the ear
and root lodging (%) ....................................46
Figure 7. Relationship between leaf number above the ear
and shading effect (cm) .................................46
Figure 8. Relationship between plant height (cm) and stalk
lodging (%) .............................................46
Figure 9. Relationship between ear height (cm) and stalk
lodging (%) .............................................46
Figure 10. Relationship between shading effect (cm) and
root lodging (%) ........................................47
Figure 11. Relationship between leaf number above the ear

and grain yield tons/ha ............. ...... ...... ...... ..47

viii

Figure 12. Relationship between moisture percentage (%) and
grain yield tons/ha .....................................47
Figure 13. Relationship between plant height (cm) and grain
yield tons/h ...... .......................................47
Figure 14. Relationship between ear height (cm) and grain
yield tons/ha ...........................................62
Figure 15. Relationship between stalk lodging (%) and grain
yield tons/ha ...........................................62
Figure 16. Relationship between root lodging (%) and grain
yield tons/ha ...........................................62
Figure 17. Relationship between ear position (%) and grain
yield tons/ha 62
Figure 18. Relationship between ear height (cm) and leaf
number above the ear ....................................63
Figure 19. Relationship between leaf number above the ear
and ear position (%) ....................................63
Figure 20. Relationship between moisture percentage (%) and
plant height (cm) .......................................63
Figure 21. Relationship between moisture percentage (%) and
ear height (cm) .........................................63
Figure 22. Relationship between moisture percentage (%) and
stalk lodging (%) .......................................64
Figure 23. Relationship between moisture percentage (%) and
root lodging (%) . ............. . .................. . ...... 64

iv

Figure 24. Relationship between moisture percentage (%) and
ear position (%) ........................................64
Figure 25. Relationship between moisture percentage (%) and
shading effect (cm) .....................................64
Figure 26. Relationship between plant height (cm) and ear
height (cm) ........ ...... ......... ........ ..............65
Figure 27. Relationship between plant height (cm) and root
lodging (%) ............. ..... ...........................65
Figure 28. Relationship between plant height (cm) and ear
position (%) ........... ............... ..................65
Figure 29. Relationship between plant height (cm) and shading
effect (cm) ....... ..... .................................65
Figure 30. Relationship between ear height (cm) and root
lodging (%) ........... .. ................................ 66
Figure 31. Relationship between ear height (cm) and ear
position (%) ............................................66
Figure 32. Relationship between ear height (cm) and shading
effect (cm) ............... ... ............. . ............. 66
Figure 33. Relationship between stalk lodging (%) and root
lodging (%) ....... ................ ......... ...... ....... 66
Figure 34. Relationship between ear position (%) and stalk
lodging (%) ................... .......... ................67
Figure 35. Relationship between shading effect (cm) and
stalk lodging (%) ..... .................................. 67

Figure 36. Relationship between ear position (%) and root
1°dgihg(%) ....O............OOOOIOOOOOOOOOOOO...00......67
Figure 37. Relationship between ear position (%) and shading

effect (cm) ............ . ................................ 67

xi

INTRODUCTION

The improvement of grain yield in maize may be
achieved through selection for characters which increase
the photosynthate supply to the ear during grain formation.
Limitation of assimilate supply by defoliation during the
flowering period can cause a substantial yield reduction (3,
39). A grain yield decrease resulting from leaf removal at
10 or 12 days after mid silking could be related to the
reduction in kernel number per plant, while grain yield
decrease associated with leaf removal at 20 or more days after
mid-silking was mostly related to a decline in kernel weight
(30,34,48).

Several researchers have suggested increasing the
assimilate supply in maize by selecting genotypes with a
high rate of photosynthesis per unit of leaf area (55); by
improving the efficiency of light interception and utilization
(21,50); by extending the grain filling period (20); by
selecting a greater leaf longevity (81). Attempts have also
been made to select a higher leaf number per plant. Hybrid
differences in leaf number have been reported by Chase and
Manda (14).

The position of the leaf relative to the ear affects
the rate and direction of assimilate translocation and
subsequently ear growth (23,82,27). Generally upper leaves

contribute a greater portion of their assimilates to the ear.

Thus, an important agronomic challenge is to redesign the
present maize plant in order to allow a higher production of
leaves at the top of the canopy. A mutant maize plant with
greater than normal leaves above the ear was observed in a
single-cross hybrid (A632XM16) seed production field by Robert
C. Muirhead of Hughes Hybrids, Inc., Woodstoch, Illinois. Seeds
from this plant were planted in a winter nursery 1971-72 and
the plants were self pollinated. Dr. D. L. Shaver, research
director for Cornnuts, Inc., Salinas, California observed the
progeny in 1972. Shaver has continued breeding and genetic
research with this mutant for 15 years. He determined that the
extra leaf trait is determined by a single dominant gene, Lfy,
conditioned by modifier genes and affected by maturity of the
genotype.

Muirhead and Shaver, as inventors, were issued a U.S.
patent in 1985 covering the use of Lfy germplasm "to enhance
the yield of maize". The patent was assigned to Cornnuts
Hybrids, Inc. who has been licensing public (Michigan State
University) and private agencies to conduct research and
development. Several Lfy synthetics and experimental early
generation Lfy inbreds were sent to Michigan State University
in 1985.

Experimental single-cross hybrids were created in 1985
from these Lfy inbreds to evaluate the agronomic potential of

the Lfy hybrid in replicated yield trials in Michigan.

REVIEW OF LITERATURE

Canopy Structure

The total amount of dry matter produced by the maize
plant is primarily a function of the size and efficiency of
the leaf area as well as its maintenance during kernel
development (80). Nichiporovich (62) reported that the leaf
area index (LAI) varies for different crops, but it is
typically in the range between 2.0 to 5.0. Muleba (59)
indicated that LAI was a determinant factor of high yield at
low plant density in both a temperate and tropical environment.

High LAI can be achieved by increasing leaf area per
plant and/or plant density. Leaf area per plant depends on
rate of leaf development by the apical meristem and the time
it takes floral initiation to trigger flowering. Extension
of the preflowering period is not always acceptable, because
it may result in lengthening of the interval between planting
and maturity (80). However, extra-leafy maize with a modifier
for earliness has a higher rate of leaf production before
tasseling and it would be more desirable in short-season
areas (74).

Crops differ in their response to increasing stand

density. Nevertheless, maize appears to be very sensitive

to thick planting. Indeed, with an increase of population
density LAI increases up to the point where a mutual shading
of the leaves at the time of spikelet initiation decreases
the net assimilate rate (39,84), plant weight (28,29), and
yield (78). Stinson and Moss, (78) suggested that low light
levels within dense plantings may reduce photosynthesis in
lower leaves which result in reduced yield. This suggestion
is in agreement with the results of Pendelton and Hammond
(66) who studied the importance of various leaf positions
within the maize canopy. They found that the relative
photosynthetic potential of the leaves at the top of the
canopy was twice as high as the middle leaves and five times
as high as the leaves at the bottom.

It is relevant to stress the simple fact that the
efficiency of sunlight to penetrate a maize canopy with a
given LAI depends on leaf orientation or leaf angle relative
to the stem (10,50). Since vertically oriented leaves usually
intercept less light at noon, they require a high LAI in order
to maximize the interception of incoming radiation on that
canopy (23,56). Duncan et al.(21) predicted in computer
simulation studies that the upright leaf orientation types
would produce a dry matter greater than horizontal leaves
when the LAI is above 3.5.

In fact, some reports do not demonstrate a response to

vertical leaf orientation (42,68,83), because the advantage

of vertical leaf orientation for yield could be realized if
narrow row spacing and high density are used (67).

It has been suggested that more vertically inclined
leaves above the ear and gradually approaching more horizontal
orientation at the base of the plant would further improve
yield (55), and would require a LAI of 10 for maximum dry
matter accumulation (24). Pendleton et al.(65) evaluated the
effect of vertically oriented leaves on grain production, by
mechanically supported leaves in a vertical position in a
commercial hybrid. They used three treatments; first, all
leaves were tied vertically; second, only leaves above the ear
were tied vertically; and finally, a normal leaf arrangement.
They concluded that plants with vertically inclined leaves
above the ear outyielded those of the same hybrid when all
leaves were vertically inclined or with a normal leaf
arrangement. Shaver (75) reported that extra-leafy hybrids
had the tendency for top leaves to start whorling above the
ear. This trend generally reduced the shading effects
resulting from the alternate arrangements of the leaves and
their closeness above one another. Further, he indicated that
extra-leafy maize responded strongly to thick plantings whereas
the normal counterparts did not satisfactorily respond to any

increase in stands above 18,000 plants per acre.

Grain Filling Period

Grain yield of maize can largely be accounted for by
dry matter accumulation during the period from silking to
grain physiological maturity. Johnson and Tanner (47) divided
the grain filling period into three different periods of
development, 1) lag period which starts at silk emergence and
continues until kernels are established and reach their full
growth rate. 2) Linear grain dry weight accumulation period
in which more than 90% of the grain dry weight was stored in
the kernels; 3) Leveling off of dry matter accumulation during
which dry weight growth declines until the black layer is
formed.

The importance of a lag period was pointed out by some
workers (26,69) because the number of endosperm cells in the
kernel is determined during this period, and it may have a
pronounced influence on potential grain size. Johnson and
Tanner (47) evaluated the length of filling period in four
inbreds and their respective hybrids grown at the same LAI.
They found that the yield difference among the material they
tested was due to either the length of the initial lag period
and/or in the length of the final period when dry matter
accumulation was leveling off. Therefore, they suggested the
use of an actual grain filling period rather than total filling
period. However, the beginning of rapid linear grain growth

is probably related to cytokinin activity in the endosperm of

maize kernels which increases to a maximum two weeks after
pollination (16,35).

In attempts to understand the differences for grain
weight production among maize hybrids, considerable attention
has been given to the duration and the rate of the grain filling
period. Several studies of different results related to length
of the filling period have been reported. Shaw and Thom (76)
observed a relatively constant time interval of 51 days was
required for three hybrids of divergent maturity over a period
of several years. Similarly Hallauer and Russell (38) reported
a relatively constant 60 day interval between silking and
maturity. 0n the other hand, Daynard et al. (18) found
differences of up to 4 days among three hybrids in their actual
filling period.

The rate of dry matter production may be linked by
the demand for assimilates during the grain filling period
(61,35). However, the rate could be enhanced by increasing
the leaf number above the ear at the time of the critical
stage in the development of potential kernel number per plant
(34,35).

Previous reports indicate that yield differences among
maize genotypes may be accounted for by differences in the
length of the period of silk emergence to grain maturity (18,
40). Hanway and Russell (40) found a significant relationship

between grain yield and the length of the filling period for

several hybrids at a single plant density. Corroborating the
above findings, Mock and Pearce (55) included the character
(long grain filling) for the development of an ideotype of
maize.

An optimum grain filling period requires a continuous
supply of photosynthetic products and their translocation to
the ear in order to obtain the desired yield potential.
However, in conditions where photosynthesis becomes inadequate
to support the constant linear rate of kernel growth, assimilate
stored earlier in both stalk and husk are probably utilized in
kernel growth. In fact, Duncan (25) suggested that the high
rate of utilization of photosynthate by the growing plant
prevents the accumulation of carbohydrates during vegetative
growth. 'Furthermore, he speculated the possibility of
carbohydrates to accumulate in temporary storage tissue during
the period between the cessation of vegetative growth and the
initiation of rapid linear dry weight increase. Support of
this idea came from the results of several researchers (3,4,
17,36), who reduced the assimilate supply either by shading or
by removing the leaves during the grain filling period. They
found an increase of kernel dry weight with a concomitant
decrease of soluble solids in the stem. But numerous workers
(12,17,52,57) have emphasized the importance of soluble solids
in the stem for the improvement of standability of the maize

plant. Nevertheless, Shaver (75) suggested that the overwhelming

supply of metabolites in extra-leafy hybrids could be exploited
by lengthening of the grain filling period through a small
introgression of Cuzco germplasm. Shaver said " we estimated
that for the compliment to Lfy, we need 74 days ". Since Cuzco
has 150 days it is possible to get that estimate to maximize
the efficiency of Lfy materials. He also indicated that the
extension of the filling period would not deteriorate the
strong, erect and springy stalk quality of extra-leafy maize.
Finally the duration and rate of grain growth can vary
substantially, depending on cultivar and environmental factors
mainly temperature and photoperiod. Temperature exerts the
greatest effect on the length, while both temperature and
photoperiod influence the rate of growth (11,46). Wilson et
al. (86) found differences in the length of the period of grain
filling for two genotypes tested under three temperature
regimes. Carter and Poneleit (13) observed significant year
differences in number of growing degree days required to
complete the period from silking to maturity. Hunter et al.(46)
indicated that higher yield was associated with longer filling
due to lower temperature which resulted in increased post-
anthesis dry matter production. They also noted that longer
photoperiod and cooler temperatures hasten the rate of grain
filling and consequently increased final dry weight in the

grain.

10

Partition of Assimilates

Development of genotypes having the number and arrangement
of leaves that support a large grain yield requires knowledge
of the dynamics of assimilates from the leaves to various plant
parts. The photosynthate distribution pattern from different
leaves is affected by the metabolic activity in the sink as
well as competition for available photosynthate. The latter
changes with the developmental stage of the maize plant. Thus,
at the beginning of the critical period for ear development,
all leaves in general contribute their assimilates to the upper
stem, leaves, tassel, and the root system. Conversely, three
weeks after silking, when the upper stem, leaves, and the
tassel have ceased growing and the ear is growing much more
rapidly, assimilate distribution patterns are shifted toward
reproductive and vegetative parts of the ear (27,29,35,43,
63). Furthermore, translocation of assimilates which enhance
the growth of the ear is influenced by the spatial relationship
between photosyntate source and sink. From C14 labeling
experiments conducted 20 days after silking, Eastin (27)
reported that the leaves above and immediately below the ear
export most of the assimilate to the developing ear, while
metabolites from lower leaves are exported preferentially to
the root and lower stem. Later on the direction of export from
lower leaves changes from downward to upward as the ear becomes

the dominant sink (82). However, the movement of carbohydrates

11

from the lower leaves to the lower stem and roots during the
early vegetative period may improve standability and root
regeneration by enhancing early development of an extensive
brace root system (75). At the same time, it is possible that
sugars are recycled through the roots and may be converted to
organic nitrogen which is translocated upward to the shoots
(82).
The rate of movement of assimilate from the leaves

is important in linking photosynthesis to growth. Leaves in
general may translocate as much as 70 to 80% of the assimilate
produced in a short time interval, depending on species and
environmental conditions. However, maize and other C4 species
are more efficient than C3 species, because of the specialized
leaf anatomy and a greater amount of phloem in the leaves (10).

Evidence indicates that detasseling as well as the use
of male sterile plants lead to a higher yield (37,20,44), and
their effect may also be more pronounced when plants are in
less favorable environments e.g. lack of moisture, higher
plant density, and inadequate minerals. Although part of the
detrimental effects of the tassel can be attributed to the
reduction in the amount of light that reaches the photosynthetic
surface in high stand density (20,44,50), it is also a part
of diversion of metabolites to the growing tassel due to
physiological dominance (60,64). The shading effect was

estimated by Duncan et a1. (20), who calculated maximum shading

12

of 19% at a density of 100.000 plants per acre. Hunter et al.
(44) also measured the effect of tassel shading on grain yield
and found a significant reduction.

The great tendency in leafy maize for protogfny may
offer a possibility of a near-elimination of these yield
pernicious aspects of the tassel (72). Shaver (72) speculated
that the pronounced delay of the tassel differentiation until
after the flowering of ear has been established, could result
in a reduction of adverse tassel shading of 10%. In addition,
he estimated another 30% gain from reduction of apical
dominance caused by production of more leaves above the ear
during the period between the differentiation of the ear and

the tassel.

-Environmental Factors Affecting Leaf Number

The number of leaves per plant in maize (Zea mays L.),
is correlated with plant size, leaf area, length of life cycle,
and consequently, adaptation of local cultural conditions (41),
particularly temperature, photoperiod, and mineral nutrition.
Duncan and Hesketh (22) studied the effect of temperature
regimes ranging from 15 to 36°C at a constant 16 h daylength
on a wide range of genotypes, and obtained an almost linear
increase in average leaf number with increase in temperature.
They also indicated that low temperature induced early tasseling

which resulted in the development of fewer leaves, fewer nodes,

13

and hence shorter plants. The positive relationship between
higher temperature and the number of leaves has been observed
by numerous workers (2,5,7,15,41,46). Chase and Nanda (14)
compared the performance of 21 double cross hybrids planted

in Illinois in May and Florida in September and November. They
showed that winter plantings tended to reduce leaf number, and
the period from seedling emergence to anthesis was much shorter
in the September planting than in the other two.

As noted by Abbe and Phinney (1) the rate of leaf
initiation was accelerated exponentially through consequentive
plastochrones. However, shortening of the plastochrone interval
between the initiation of successive leaves was attributed to
warm temperature (46).

It is nevertheless suggested that while the meristematic
region of the shoot remained below the soil surface level
during the period of leaf initiation, the higher root zone
temperature increased the rate of leaf appearance as well as
the maximum number of leaves finally initiated per plant (6).

The transition period from vegetative to reproductive
development is the critical phase in determining leaf number
in maize (5,6,41). Arnold (5) reported that leaf number of
Golden Cross Bantam was sensitive to temperature from the
four-leaf stage to tassel differentiation .

Numerous studies have been made concerning the effect

of photoperiod on leaf number in maize (45,49). Most genotypes

14

showed development of more leaves, although genotypes differ
in day length reaction. Bonaparte (7) examined three single
cross hybrids under controlled environments, and found an
appreciable increase in leaf number in a 16 h than a 12 h day
length at the same temperature regime. Francis et al. (33)
reported a similar effect of shortened nights on a wide
variety of races of maize and also noted a difference among
genotypes in their sensitivity to difference in the length

of the dark period. However, development of more leaves by
altering day length may delay not only tassel differentiation
but also silking relative to pollen shedding (2).

It has been shown that mineral nutrients have a remarkable
effect in increasing leaf area per plant (31,51). However,
increasing leaf area does not necessarily produce a higher
yield unless the application of the nutrients, particularly
nitrogen, coincides with the developmental rhythm of the plant
for maximum benefit (54). Thorne and Watson (79) observed that
an application of nitrogen fertilizer to wheat in April had
almost doubled the leaf area, while an application of the same
amount of nitrogen at the time of heading resulted in a small
increase of leaf area, but there was a nearly equal increase
in yield. Eik and Hanway (31) found an increase of mean numbers
of leaves formed per plant when a greater supply of nitrogen
was applied at planting. In addition, they observed that a

faster rate of leaf emergence and leaf area expansion were very

15

pronounced compared to the control plots. Bonaparte and Brown
(8) reached a similar conclusion, when they examined 25 hybrids
at a number of locations in Canada and the United States. In
contrast, Hesketh et al. (41) indicated no significant change
in leaf number for plants of B14xB37 grown at different
nutrient levels.

Phosphorus and potassium stimulate greater leaf area
whenever they are applied in the early stages of growth.
Furthermore, potassium may delay the aging process of the
leaves either alone or by interacting with other essential
nutrients, whereas, phosphorus may hasten leaf senescence

when it is applied at a late stage of plant development (54).

Genetics Improvement of Leaf Number

Increase of leaf number above the ear for enhancing
of photosynthetic supply is a principal strategy to be
considered in a selection program designed to improve yield
potential of maize. Although maize breeders have attempted
to reduce ear height in order to improve plant standability,
they lowered the physical position of the ear instead of
altering the proportion of nodes and leaves above the ear
(71).

Limited work has been done on the inheritance of leaf
number in maize. Lorenzoni (53) studied the breeding behavior

of leaf number and concluded that the character was partially

16

dominant. Similarly Stein (77) observed dominance for leaf
number. The inheritance of leaf number was further investigated
by Bonaparte (9) in a diallel cross among six inbreds. He found
that leaf number was partial dominance and a high proportion of
the total variation was accounted for by additive gene effects.
He also noted that at least one effective factor was conditioned
for the expression of the trait. Shaver (73) conducted an
eXperiment to assess the effect of mass selection for high leaf
number above the ear in a synthetic which had higher leaf
number. After four cycles he obtained a high frequency of
barren plants and low frequency of desirable phenotypes. He
concluded that the average leaf number was around 9 and
selection for high leaf number in normal maize could be
counterproductive. Recent discovery of maize genotypes which
possess a genetic factor capable of conferring the extra—leafy
character has opened a new horizon in maize breeding. The
extra-leafy phenotype is conditioned by a simple dominant gene.
The action of this gene (Lfy) is to change the architecture of
the plant by doubling the number of leaves above the ear and by
extending flowering time for at least three days (58). Since
the Lfy gene arose as a mutation, Shaver examined the stability
of the gene and found that Lfy was stable.

Shaver reported that Lfy could be transmitted by any
conventional breeding technique, and from the beginning of his

work he used early inbreds to produce good Lfy versions. So,

17

from those materials he developed eight advanced synthetics
which showed a yield advantage compared with their normal

counterparts.

18

MATERIALS AND METHODS

The germplasm used in this study consisted of seventy two
single-cross hybrids. Sixty four were experimental hybrids
bearing the Lfy gene. These hybrids were produced at Michigan
State University in 1985 from early generation Lfy inbreds
received from Dr.D. L. Shaver and selected at M.S.U. Seven
commercial single-cross hybrids were included as normal
non-leafy hybrids for comparison. One of these, B73XMS71 was
included as two entries, 71 and 72. Pedigrees of the hybrids
is presented in Table (1).

Evaluation of the hybrids was carried out in Cass and
Saginaw Counties, Michigan in the summer of 1986. The Cass
County field (Oshtemo sandy loam) was planted on May 2 and
the Saginaw County field (Park Hill loam) was planted on
May lst. -Total fertilizer (N-P-K) amounts applied were
282-50-149 and 321-63-63 kg/ha in Cass and Saginaw counties
respectively. The Cass County experiment was conducted with
13 cm of supplemental irrigation applied with a center pivot
system. Growing conditions at both locations were good,
resulting in relatively high yields.

The experimental design was an 8 X 9 simple rectangular
lattice with two replications at each location. Single-row
plots 11.1 m long with 76 cm between rows were used. Final
stands were approximately 55,000 plants/ha at both locations.

All trials were planted and harvested by machine without gleaning.

19

Grain yields were adjusted to 15.5% moisture and
converted to kg/ha. Root lodging refers to percentage of
plants leaning more than a 30 degree angle from vertical.
Stalk lodging is the percent of plants broken below the first
ear.

The following agronomic characteristics were recorded
for a sample of four plants from each plot. Leaf number was
recorded above the upper ear. Plant height was measured in
centimeters from the base of the plant to the point of tassel
branching. Ear height was measured in centimeters from the
base of the plant to the node bearing the primary ear. Relative
ear position was determined by the ratio of ear height and
plant height.

Leaf shading was calculated as the distance between
two leaves on the same side of the stalk, estimated by the
following formula:

Shading effect = Ph-Eh / L no. * 2
where Ph = plant height
Eh é ear height and
L no. = number of leaves above the primary ear.
2 = Coefficient used to measure the length of two leaves
(3 nodes), on the same side of the stalk.
. Analyses of variance for a simple lattice design was
applied to the data of all characters. Hybrid means adjusted

for lattice block differences were used in the combined

20

analyses over locations. In cases where a randomized complete
design analysis was more efficient than the lattice, the
unadjusted hybrid means were used for the combined analysis.
Hybrids were considered fixed effects, and the two locations
were considered random for determining expected mean squares.
For the combined analysis over locations, a pooled average
effective error was calculated by pooling the degrees of
freedom and sums of squares for the error term at each
experiment over all hybrids. The form of the analysis of
variance including expectations of mean squares is shown in
Table (2).

Interrelationships among all agronomic characters for
each location and over locations were determined by simple
correlations. Stepwise multiple regression analysis was used

to determine which character(s) contributed to grain yield.

TABLE 1.

21

PEDIGREEB OF LEAF! AND NON LEAF! HYBRIDS

 

ENTRY CHILE

 

so. now no. PBDIGRBB

1 2151*1- -1x2293—4 B73Lfysyn. XA257)B73Lfysyn.XInb. 337Lfy

2 2151- 1- -2x2252- 2 X(101X293)

3 2151-2-1X83-c, 9119 ” " " XInb. 957Lfy/Lfy
4 2151-2-2x2252-2 " " " X(101X293)

5 2152-1-1X83-c,9119 " " " XInb.957Lfy/Lfy
6 2152-1-2x2252-2 " " " X(101X293)

7 2152-2-1xs4-c,3145 " " " XInb.37lLfy

8 2152—2-2x2252-2 " " " X(101X293)

9 2153-1-1xa4-c3145 " " " XInb.371Lfy

10 2153-1-2x2252-2 " " " X(101X293)

11 2153-2-1xe4-c,3145 " " " XInb.37lLfy

12 2153-4-1x2252-2 " " " X(101x293)

13 2154-2-1X83-c,9228 " " " XInb.371Lfy/Lfy
14 2154-3-1X83-c,9228 " n " "

15 2157-1-1x2254-1 [(632 LfyXA257)632Lfy] X(101X293)

16 2158-1-1x2254-1 . " " "

2158-2-1X2254-2
2158-3-1X2230-1
2158-3-2X2254-2
2158-4-1X2261-3
2158-5-1X2299-1
2158-6-1X2299-1
2160-1-1X83-C,9228
2163-1-1X83-C,9113
2163-1-2X2254-2
2163-2-1X83-C,9113
2163-3-1X83-C,9113
2164-1-1X83-C,9113
2166-1-1X2254-1
2166-2-1X83-C,9113
2166-3-1X2299-1
2266-SQ1X2254-1
2166-5-2X2299-1
2166-6-1X83-C,9113
2166-1-1X2254-1
2169-1-1X83-C,9113
2169-2-1X83-C,9113
2169-3-1X83-C,9113
2169-4-1X83-C,9113
2227-1-1X2261-3
2228-2-1X2252-2
2228-3-1X2261-2

[(632LfyXA257)637ELfy]
II II II

(632LfyXA257)371ELfy
II II II

(A632X637ELfy)
II II
(A632X637ELfy)
II II
II II
II II
II II
(632LfyX957)

II II
II II

(Wf9EX101Lfy)101Lfy
II II

xsaszy c R F
X(101X293)
II

XB79Lfy

II
XInb.371Lfy/Lfy
XInb.941Lfy/Lfy
X(101X293)
XInb.941Lfy/Lfy
XINb.941Lfy/Lfy

II

X(101X293
XInb.941Lfy/Lfy
XB79Lfy
X(101X293)
XB79Lfy
XInb.941Lfy/Lfy
X(101X293)
XInb.941Lfy/Lfy
II

X(101X293)
II

 

TABLE 1. Cont.

22

 

ENTRY CHILE

 

no. new no. PBDIGRBE
43 2228-3-2x2294-1 (Wf9EX101Lfy)101Lfy X337LFy
44 2228-4-1x2261-2 " n " X(101X293)
45 2228-4-2x2294-1 " " X337Lfy
46 2230-1-1x2261-2 632Lfy c R F X(101X293)
47 2230-1-2x2294-1 " X337Lfy
48 2230-2-1x2261-2 632Lfy c R F X(101X293)
49 2230-3a1x2261-2 " x101x293)
so 2230-3-2x2299-1 " XB79Lfy
51 2230-4—1x2261-1 " X(lOlX293)
52 2230-5-1x2299-1 " XB79Lfy
53 2235-1-1x2299-1 " "
54 2235-2-1x2293-5 " XInb.337Lfy
55 2235-3e1x2252-2 " X(1o1x293)
56 2235-3-2x2261-1 " "
57 2250-1-1x2261-1 637ELfy "
58 2250-2-1x2261-1 " "
59 2250-3-1x2261-1 " "
60 2260 B-2-lX2293-3 (101LfyX293) XInb.337Lfy
61 2260 B-3-1X84 T,109-14 " " xe14 Lfy
62 2260 B-3-2X2293-3 " " XInb.337Lfy
63 2265-1-1x2293-2 (lOlLfyXA635)A635 "
64 2265-3-1x2293-2 " n " "
65 . CBS9I x LH39
66 LH74 x LH39
67 FR3l x FR20A
68 A632 x CBSQI
69 LH119 x CBS9I
7o LH74 x LHSl
71 B73 x M871

II II

72

 

23

Table 2. Analysis of variance used to estimate component of
variance for locations and hybrids.

 

 

SOURCE OF VARIANCE D.F. EXPECTATIONS OF MEAN SQUARES
. l 1
LOCATIONS L-l d+rh+¢3L
1 2.
HYBRIDS H-l d+r1+gH
LOCATIONS x HYBRIDS (L-l) (H-l) afréin
. 2
POOLED ERROR DFl + DF2 6’
g 2
EL = Variance due to differences among locations.
2'H = Variance due to differences among hybrids.

Variance due to interaction of location with hybrids.
DFl and DF2 = degree of freedom for experiments 1 and 2
respectively.

plant height ,

£:> Shading effect

__”_______.__/¥-_——

r----
ear height

.A.
.2

 

D

 

Calculation of shading effect:

Ph - Eh
Shading effect = * 2

 

L no.

265.7 - 74.1

9.4

Fig. 1. Plant measurements and the calculation of shading

effect.

25

RESULTS

-Means of the nine agronomic characteristics of leafy
and their non-leafy (commercial) check hybrids are reported
in table (3). Non-leafy hybrids were generally earlier in
maturity than leafy hybrids as reflected by grain moisture
content. The mean grain yield of leafy hybrids was 88% of
the check non-leafy hybrids. Leafy hybrids averaged 31 cm
taller and developed an avarege of four more leaves above the
ear node than the check hybrids. Ear height relative to plant
height was slightly lower (2.7%) for leafy hybrids. Stalk and
root lodging averaged higher for leafy hybrids. Shading effect
was lower for leafy hybrids.

Table 4 and 5 present means for the nine characteristics
for each of the 72 hybrids at two locations. Growing conditions
produced good yields (9530 and 9304 kg/ha) at both locations.
Plant height (269.6 vs 249.4 cm) and ear height (84.6 vs 78.0
cm) averaged slightly higher at Cass County than in Saginaw
County. Stalk lodging (10.1 vs 2.4%) and root lodging (7.7
vs 0.7%) averaged higher in Cass plots.

Means for both locations combined are presented in
Table 6. Four of the best yielding Lfy hybrids (entries 36,
4,34,30) were at least equal to the best commercial check
hybrids (entries 72,71,70). Moisture content was slightly
higher for these four Lfy hybrids. There was no significant

difference in stalk and root lodging. These four Lfy hybrids

26

averaged 3.4 more leaves above the ear node than the checks
(table 7).

In table 8. the four ”best" Lfy hybrids (36,4,34,30)
averaged 12,614.0 kg/ha (Table 6) while five commercial check
hybrids (65,66,67,68,69) averaged 9,364.1 kg/ha, a difference
of 34.7% for these four Lfy hybrids. In this comparison, the
Lfy hybrids were later in maturity averaging 24.8% in moisture
compared to 21.3% for the five checks. Average leaf numbers
were 9.4 vs 6.2. Stalk lodging was 4.5% and 4.4%, root lodging
was 2.7% and 0.4%, plant height was 260.5 and 224.8 cm and
ear height was 74.3 and 71.3 cm for Lfy and check averages
in this comparison.

Analyses of variance for nine characteristics for each
location and for locations combined are given in the Appendix,
tables 10-12. The source of variance due to differences among
hybrids was highly significant at both locations for all
characteristics except root lodging which was significant at
5% level in Saginaw County.

The mean values for nine morphological and physiological
characteristics of seventy two hybrids grown at both Cass and
Saginaw counties are presented in tables (4 and 5)
respectively.

The grain yield of the hybrids grown in Cass county ranged
from 4768 to 13523 kg/ha. The highest yield was produced by

No. 36, while the lowest yield was produced by No. 18, even

27

though both hybrids had an average of 9 leaves above the
primary ear. The former one exhibited a greater distance
between leaves on the same side. At Saginaw, the grain yield
was ,in the range between 5459 and 13196 kg/ha. The best
performing hybrid was No. 71, which had an average of 6 leaves
above the primary ear. In contrast, the poorest performing
hybrid was No. 61, with an average of 13 leaves above the
primary ear. Leaf number above the primary ear ranged from 6
to 14 in Cass County, and from 5 to 14 in Saginaw County. At
both locations the non-leafy hybrids had developed fewer leaves
but they had longer internodes above the primary ear compared
to their leafy counterparts. Plant height ranged from 205.8
to 309.1 cm, and from 194.5 to 287.9 cm at both locations
respectively. Ear height was 61.9 to 112.1 cm and 60.1 to
98.1 cm at both locations. The range of stalk and root lodging
at Saginaw County was 0.0 to 6.5 and 0.0 to 15.5% respectively,
with an average of 0.7% for stalk lodging and 2.4% for root
lodging. However, most of the hybrids showed a higher rate of
lodging in Cass County and the range of stalk lodging was
between 0.0 to 33.4% with an average of 10.1%. For root
lodging, the range was 0.0 to 51.9% with an average of 7.7%.
The Combined location analysis of variance showed highly
significant differences among hybrids and locations for all

characteristics except for ear position and root lodging.

28

These two characteristics were non significant among locations
and hybrids respectively (table 12). The interactions between
hybrids and locations were highly significant for grain yield,
moisture content, ear height, root lodging and ear position.
The interactions did not differ significantly for leaf number,
plant height, stalk lodging and shading effect.

The interrelationships among grain yield, moisture
percentage, leaf number, plant and ear height, stalk and root
lodging, ear position as well as shading effect are presented
in table (9) There was considerable variation in the correlation
coefficients between all characters studied. The small negative
correlation coefficient between grain yield and leaf number
indicated that there is little relationship between grain yield
and leaf number above the primary ear. Similarly there were
limited negative relationships between grain yield and both
stalk and root lodging. A significant positive correlation
existed between leaf number above the primary ear and maturity
which was indirectly determined by grain moisture content. The
leaf number also had a good relationship with plant and ear
height as well as stalk and root lodging. A substantial
association existed between maturity and plant height, but a
slight association was found between maturity and ear height.
There was a negative correlation between shading effect and all
characters, except grain yield in which the improvement of

shading effect increased grain yield.

29

The regression analysis indicated that plant height and
shading effect were the most influential characteristics for

grain yield.

30

TABLE 3. MEANS OF NINE MORPHOLOGICAL AND PHYSIOLOGICAL
CHARACTERISTICS OF LEAEY AND COMMERCIAL CHECK
HYBRIDS AVERAGED OVER LOCATIONS

 

TYPE OF HYBRID

 

 

Characteristics Leafy Commercial check Difference
Grain yield 9281.1 10510.4 -1229.3
Moisture % 25.1 22.5 2.6
Leaf number 9.9 6.2 3.7
Plant height 262.7 231.8 30.9
Ear height 81.8 78.7 3.1
Stalk lOdging 6.6 4.4 2.2
Root lodging 4.7 0.6 4.1
Ear position 31.2 33.9 —2.7

Shading effect 36.9 49.9 -13.0

 

31

TABLE 4. MEAN VALUES FOR NINE MORPHOLOGICAL AND PHYSIOLOGICAL
CHARACTERISTICS OF SEVENTY THO HYBRIDS AT CASS COUNTY

 

ENTRY GRAIN MOIST LEAF PLANT EAR STALR ROOT EAR Shading

 

NO. YIELD one no. HT um LODG. LODG. P08. Effect
xe/na % on on % t t on
36 13522.7 24.5 8.6 273.5 78.0 12.2 7.6 28.5 45.5
34 12786.5 22.9 8.6 264.7 77.0 2.9 0.0 29.1 43.7
4 12700.8 27.1 10.1 257.1 71.2 4.6 9.6 27.7 36.8
3 12658.9 27.0 9.7 281.7 83.0 5.1 3.1 29.5 41.0
72 12302.2 24.5 6.3 251.2 86.9 5.6 2.9 34.6 51.8
11 12269.6 26.3 9.9 285.5 73.9 6.0 3.9 25.9 42.5
1 12247.6 24.6 10.6 255.6 79.1 2.4 31.2 30.9 33.3
71 12075.4 24.5 5.8 250.9 93.7 11.4 0.0 37.3 53.7
33 12037.8 23.4 10.3 287.2 80.1 4.5 7.8 27.9 40.4
30 11867.1 21.7 9.9 279.3 82.9 8.9 4.8 29.7 39.9
17 11797.3 23.0 10.6 280.6 112.1 15.2 10.9 40.0 31.8
9 11623.4 27.8 9.9 276.6 76.4 9.5 5.6 27.6 40.6
54 11607.7 28.4 11.9 277.6 92.9 12.0 10.0 33.5 31.2
70 11467.9 23.5 6.1 253.9 101.2 2.2 2.7 39.9 50.1
7 11408.3 27.5 8.7 264.4 74.9 7.1 2.0 28.3 43.6
10 11249.6 24.8 11.1 285.0 89.6 5.6 13.6 31.4 35.2
58 11198.4 23.5 11.7 299.4 86.4 11.6 7.1 28.9 36.4
45 11052.6 23.3 11.7 283.0 99.2 25.0 26.7 35.0 31.4
59 11016.2 25.6 11.4 305.2 96.7 7.4 0.3 31.7 36.7
31 10938.4 22.3 7.9 273.4 87.8 4.3 0.0 32.1 46.7
35 10326.5 23.8 9.9 263.0 93.4 11.6 1.0 35.5 34.4
60 10303.4 27.4 12.9 299.7 102.9 22.6 37.1 34.3 30.6
38 10278.3 23.4 9.9 276.2 80.8 9.9 7.2 29.3 39.7
12 10082.0 24.5 12.2 281.3 81.3 2.6 26.6 28.9 32.8
23 10052.4 23.3 8.9 297.2 112.1 33.4 1.9 37.7 41.8
53 10034.5 27.5 11.0 307.2 94.1 7.5 1.7 30.6 38.7
67 10017.9 20.4 6.0 248.1 72.3 6.6 0.0 29.1 58.6
32 9940.4 24.7 9.9 255.7 85.3 12.5 1.1 33.3 34.3
27 9904.7 23.7 10.4 267.8 68.7 13.8 4.3 25.7 38.5
15 9734.4 23.5 10.9 269.7 87.6 4.6 13.5 32.5 33.6”
50 9714.8 25.4 7.6 280.4 93.4 6.1 0.4 33.3 49.2
44 9677.5 24.0 11.4 276.8 95.4 18.9 7.3 34.5 32.0
28 9548.9 23.7 10.4 303.8 76.1 29.6 0.0 25.1 44.0
20 9527.8 27.6 12.7 288.3 94.3 18.5 1.5 32.7 30.6
29 9505.3 25.9 10.4 288.0 94.8 17.3 11.6 32.9 37.3
19 9468.9 23.2 9.9 278.4 109.7 17.0 0.6 39.4 33.9
37 9430.3 26.3 9.1 278.0 72.7 0.0 1.0 26.2 45.1
26 9385.6 23.5 10.4 284.4 70.9 22.7 3.0 24.9 40.9

 

32

 

 

TABLE 4. cont.
57 9326.0 26.4 11.7 295.8 86.2 4.6 9.7 29.2 35.8
56 9251.6 24.6 11.9 282.7 90.4 11.9 10.0 32.0 32.5
39 9217.5 22.9 9.1 282.2 87.5 13.4 2.2 31.0 42.8
6 8924.2 25.8 10.4 269.2 80.3 0.0 1.3 29.8 36.2
16 8857.5 24.8 10.3 271.4 95.3 14.8 3.7 35.1 34.4
49 8855.6 23.1 6.8 233.1 79.8 6.0 1.8 34.2 45.4
68 8778.0 20.6 6.7 234.4 75.1 6.1 0.5 32.0 47.6
24 8772.6 26.3 10.4 272.2 71.1 12.7 7.0 26.1 38.9
42 8672.5 22.6 10.9 256.1 83.1 8.4 21.5 32.5 31.9
47 8635.2 24.7 13.1 274.7 95.1 9.4 18.9 34.6 27.4
8 8632.2 27.3 8.4 262.5 76.9 4.7 12.3 29.3 44.5
63 8619.9 20.7 6.6 205.8 63.8 3.9 4.5 31.0 43.0
65 8586.9 20.5 6.1 225.0 76.4 6.0 1.6 34.0 48.7
48 8516.6 23.4 7.1 233.7 84.4 7.8 6.4 36.1 42.0
2 8438.9 25.1 11.1 284.3 90.0 5.6 14.1 31.6 35.0
21 8280.8 25.1 9.5 280.9 85.0 7.8 5.8 30.3 41.2
66 8257.2 20.4 6.8 229.4 77.1 4.3 0.6 33.6 44.5
69 8090.0 21.5 6.3 222.9 61.9 13.2 0.5 27.7 51.5
55 8040.7 26.6 10.7 258.7 93.0 16.0 6.7 35.9 31.0
5 7888.5 28.5 10.3 309.1 84.2 2.2 10.2 27.3 43.9
25 7884.7 25.5 11.1 303.4 107.5 30.0 18.9 35.4 35.3
13 7874.5 25.6 8.4 275.4 80.1 7.1 7.7 29.1 46.2
22 7844.2 26.4 10.3 295.8 94.3 11.9 0.8 31.9 39.3
61 7745.8 27.9 13.9 286.3 72.7 0.0 4.5 25.4 30.8
62 7706.6 29.5 14.4 298.4 88.8 3.3 51.9 29.8 29.2
41 7498.4 25.3 10.4 234.9 67.0 12.3 13.9 28.5 32.1
14 7190.5 25.5 8.5 274.1 80.3 5.8 6.5 29.3 45.6
51 7151.4 23.5 7.5 234.5 83.5 7.7 3.1 35.6 40.3
64 6997.1 21.0 6.8 224.4 74.8 7.4 4.4 33.3 43.7
46 6969.0 26.5 6.4 216.8 78.7 14.2 1.9 36.3 42.8
40 6770.5 22.1 12.1 272.8 90.4 23.0 5.1 33.1 30.1
43 6308.5 24.2 11.4 282.4 90.3 18.4 24.1 32.0 33.6
52 6061.5 25.5 7.3 267.0 80.9 7.3 1.1 30.3 50.6
18 4767.9 24.0 8. 246.1 77.1 9.1 2.4 31.3 39.3
MEAN 9530.2 24.6 9.7 269.6 84.6 10.1 7.7 31.4 39.6
RANGE 13522.7 29.5 14.4 309.1 112.1 33.4 51.9 40.0 58.6
4767.9 20.3 5.9 205.8 61.9 0.0 0.0 24.9 27.4
LSD 814.5 1.7 1.8 18.7. 14.5 19.0 19.0 5.0 7.3
LSD(0°01326.5 1.3 1.4 14.3 11.2 14.6 14.6 3.9 5.6
.60.05)
C. . 3.3 2.6 7.0 2.7 6.6 72.2 94.7 6.2 7.1

33

TIbLE 5. MEAN VALUES FOR NINE MORPHOLOGICAL AND PHYSIOLOGICAL
' CHARACTERISTICS OF SEVENTY THO HYBRIDS AT SAGINA' COUNTY

 

ENTRY GRAIN MOIST LEAF PLANT EAR STALE ROOT EAR Shading
NO. YIELD URE NO. HT HT LODG. LODG. POS. Effect

 

KG/Ba % CI on % % % on

71 13195.7 25.0 6.0 243.1 82.8 .4 0.0 34.1 53.3
72 13017.6 25.0 6.0 229.8 88.3 3.9 0.0 38.4 47.3
36 12856.4 27.0 10.2 257.9 70.1 0.9 0.0 27.2 36.9
30 12695.5 24.5 10.2 269.0 75.6 2.3 0.0 28.1 37.8
70 12466.3 24.2 5.9 231.5 93.8 1.6 0.0 40.5 47.1

4 12404.6 24.7 9.0 241.4 68.3 1.1 0.0 28.3 38.4
34 12078.0 25.7 8.6 240.7 70.3 2.7 0.0 29.2 39.6

3 11834.2 27.7 9.5 249.2 76.3 2.3 2.4 30.6 36.6
33 11590.3 25.1 11.0 259.4 62.7 6.0 0.0 24.2 35.8
54 11366.2 27.5 12.0 259.6 85.1 1.8 2.5 32.8 29.0
17 11248.6 24.1 9.8 260.1 85.3 0.2 0.0 32.8 35.5
67 11176.4 21.6 5.4 226.3 75.6 2.2 0.0 33.4 56.1
13 11093.0 23.9 8.8 258.1 82.2 1.2 0.0 31.8 40.2
11 11035.8 27.8 9.1 249.8 71.8 0.5 0.0 28.8 38.9
37 10969.2 27.1 9.3 257.1 71.3 1.0 0.0 27.7 39.8
58 10959.4 25.3 11.5 270.1 73.9 0.3 0.0 27.4 34.1
45 10877.7 25.4 11.4 273.9 95.3 0.3 0.0 34.8 31.2
23 10848.9 23.1 8.8 255.3 90.3 0.8 0.0 35.4 37.3
20 10696.9 25.5 12.1 274.7 80.6 1.8 0.0 29.3 32.2

9 10676.3 28.1 11.2 259.5 72.5 3.3 0.0 27.9 33.4
31 10664.5 25.1 8.8 256.2 70.9 1.2 0.0 27.7 42.1
38 10611.7 26.2 9.0 254.7 72.8 3.5 0.0 28.6 40.6

1 10598.9 26.2 10.3 253.1 83.9 0.0 2.0 33.2 33.0
59 10501.5 25.2 11.0 268.9 70.3 9.4 0.0 26.1 36.1
65 10354.5 23.1 6.1 212.6 69.4 0.2 0.0 32.7 47.3
69 10262.7 21.4 6.0 210.8 60.8 2.3 1.0 28.8 49.7
12 10024.0 21.7 10.4 246.1 77.3 0.6 0.9 31.4 32.4
35 25.6 9.3 242.2 77.6 4.3 0.9 32.0 35.4
27 23.5 9.2 253.8 71.3 1.9 1.3 28.1 39.6
15 26.5 10.8 244.5 75.7 1.5 0.0 31.0 31.3

2 24.6 9.0 237.0 70.3 0.6 0.0 29.7 37.2
10 26.8 9.3 265.2 82.6 5.4 0.0 31.2 39.1

7 27.3 8.9 258.3 73.9 0.2 3.1 28.6 41.4
68 20.0 6.7 213.2 71.1 0.4 0.0 33.3 42.2
16 24.0 8.9 241.1 81.6 3.7 1.1 33.8 36.0
50 28.4 7.7 246.5 73.3 2.0 1.0 29.7 44.8
28 24.6 10.2 269.6 60.1 4.5 0.0 22.3 41.0
,21 26.7 9.2 260.7 93.9 0.0 0.0 36. 36.4

 

TABLE 5. cent.

34

 

 

26 8918.6 24.7 9.6 266.9 68.6 4.2 0.0 25.7 41.1
32 8895.9 26.7 10.2 225.6 65.4 1.3 0.0 29.0 31.4
66 8890.1 23.0 6.3 224.7 73.3 2.7 0.0 32.6 47.9
8 8766.8 24.2 8.7 236.1 78.5 0.0 0.0 33.2 36.1
24 8743.8 23.2 10.4 249.5 82.2 1.5 0.0 33.0 32.3
55 8546.6 30.0 9.8 218.3 79.5 4.2 0.9 36.4 28.2
5 8508.5 25.5 10.3 287.9 85.8 3.7 1.4 29.8 39.3
60 8468.2 30.7 13.6 284.1 89.8 2.0 6.3 31.6 28.6
39 8431.4 27.2 9.1 271.3 81.7 2.9 0.0 30.1 41.6
44 8357.2 27.6 10.6 255.2 86.2 1.2 6.5 33.8 32.0
57 8345.7 24.2 11.2 285.6 83.8 15.5 2.0 29.4 36.0
49 8338.4 22.8 6.8 228.8 80.0 4.8 0.0 35.0 43.8
29 8306.4 26.6 10.5 261.8 89.9 4.8 0.0 34.4 32.8
25 8305.7 26.6 10.8 279.1 98.1 1.9 2.2 35.1 33.7
53 8293.0 27.3 10.1 276.5 81.2 2.6 0.0 29.4 38.6
22 8207.0 24.7 9.8 261.6 82.6 2.3 0.0 31.6 36.6
47 8118.3 24.3 11.8 260.1 88.7 0.4 3.4 34.1 29.2
63 7918.5 23.8 6.3 194.5 61.9 3.0 0.0 31.9 42.1
48 7892.4 24.1 7.4 214.1 73.3 0.6 0.0 34.3 37.9
42 7727.9 26.2 10.8 242.2 78.9 2.0 0.0 32.6 30.4
19 7440.7 24.0 9.0 251.0 82.6 2.4 1.0 32.9 37.4
14 7372.8 24.5 8.9 251.5 77.6 3.0 0.0 30.9 39.2
62 7365.5 25.5 13.3 269.0 79.3 6.2 1.9 29.5 28.5
56 7317.3 26.7 12.1 255.5 82.9 1.5 2.0 32.5 28.6
6 7125.2 27.4 10.7 244.8 77.6 3.4 0.0 31.7 31.3
41 6777.8 28.5 10.3 231.6 79.1 1.7 3.6 34.2 29.7
40 6738.8 22.7 12.0 249.1 84.7 3.4 0.0 34.0 27.3
64 6582.0 24.5 7.2 197.0 62.5 0.0 0.0 31.7 37.4
52 6386.0 24.5 8.2 255.0 75.3 1.9 0.0 29.6 43.8
46 6178.1 24.1 6.6 198.2 71.3 4.2 0.0 35.9 38.5
43 6074.0 23.8 11.5 260.6 86.6 4.1 2.4 33.2 30.2
51 5770.9 26.6 7.3 223.1 79.3 2.0 1.4 35.6 39.3
18 5695.6 20.9 8.7 230.4 83.6 2.2 0.0 36.3 33.8
61 5459.0 27.1 13.2 268.3 72.2 0.0 0.0 26.9 29.8
MEAN 9304.0 25.3 9.4 249.4 78.0 2.4 0.7 31.4 37.4
RANGE 13195.6 30.7 13.6 287.9 98.1 15.5 6.5 40.5 56.1
5459.0 20.0 5.4 194.5 60.1 0.0 0.0 22.3 27.3

LSD 750.9 1.2 1.6 25.8 17.5 6.3 4.3 6.5 7.9
LSDO°01577.6 0.9 1.2 19.9 13.4 4.8 3.3 5.0 6.1
c.69'05) 3.1 1.8 6.5 4.0 8.6 98.8 232.5 7.9 8.1

35

TABLE 6. MEAN VALUES FOR NINE MORPHOLOGICAL AND PHYSIOLOGICAL
.CHARACTERISTICS COMBINED OVER LOCATIONS

 

ENTRY GRAIN MOIST LEAP PLANT EAR STALE ROOT EAR Shading

 

NO. YIELD URE NO. HT HT LODG. LODG. P08. Effect
ltd/Ha % on on % % % cm

36 13189.6 25.8 9.4 265.7 74.1 6.6 3.8 27.9 40.8
72 12659.9 24.8 6.2 240.5 87.6 4.7 1.5 36.4 49.6
71 12635.5 24.7 5.9 247.0 88.3 6.4 0.0 35.7 53.5
4 12552.7 25.9 9.6 249.3 69.8 2.9 4.8 28.0 37.6
34 12432.3 24.3 8.6 252.7 73.7 2.8 0.0 29.2 41.6
30 12281.3 23.1 10.0 274.2 79.3 5.6 2.4 28.9 38.8

3 12246.5 27.3 9.6 265.4 79.6 3.7 2.8 30.0 38.8
70 11967.1 23.9 6.0 242.7 97.5 1.9 1.4 40.2 48.6
33 11814.1 24.3 10.6 273.3 71.4 5.2 3.9 26.1 38.0
11 11652.7 27.0 9.5 267.7 72.9 3.2 1.9 27.2 40.8
17 11522.9 23.5 10.2 270.3 98.7 7.7 5.5 36.5 33.6
54 11486.9 27.9 11.9 268.6 89.0 6.9 6.2 33.1 30.1

1 11423.2 25.4 10.4 254.3 81.5 1.2 6.6 32.1 33.1
9 11149.9 27.9 10.5 268.0 74.4 6.4 2.8 27.8 36.8
58 11078.9 24.4 11.6 284.8 80.2 5.9 3.6 28.2 35.3
45 10965.2 24.4 11.6 278.4 97.3 2.7 3.4 34.9 31.3
31 10801.4 23.7 8.4 264.8 79.4 2.7 0.0 30.0 44.3
59 10758.9 25.4 11.2 287.1 83.5 8.4 0.2 29.1 36.4
67 10597.2 21.0 5.7 237.2 73.9 4.4 0.0 31.2 57.4
10 10461.6 25.8 10.2 275.1 86.1 5.5 6.8 31.3 37.0
23 10450.7 23.2 8.8 276.3 101.2 7.1 1.0 36.6 39.6
38 10445.0 24.8 9.4 265.5 76.8 6.7 3.6 28.9 40.1
7 10413.0 27.4 8.8 261.4 74.4 3.7 2.6 28.5 42.5
37 10199.8 26.7 9.2 267.6 72.0 0.5 0.5 26.9 42.4
20 10112.4 26.6 12.4 281.5 87.4 0.1 0.8 31.1 31.3
35 10103.9 24.7 9.6 252.6 85.5 8.0 1.0 33.8 34.9
12 10053.0 23.1 11.3 263.7 79.3 1.6 3.8 30.1 32.6
27 9880.0 23.6 9.8 260.8 70.0 7.9 2.8 26.9 39.0
15 ~ 9738.8 25.0 10.8 257.1 81.6 3.1 6.7 31.7 32.4
13 9483.8 24.8 8.6 266.8 81.2 4.2 3.9 30.4 43.1
65 9470.7 21.8 6.1 218.8 72.9 3.1 0.8 33.3 48.0
32 9418.1 25.7 10.1 240.7 75.4 6.9 0.6 31.3 32.8
50 9406.7 26.9 7.7 263.5 83.3 4.1 0.7 31.6 47.0
60 9385.8 29.0 13.2 291.9 96.4 2.3 1.7 33.0 29.6
28 9248.6 24.1 10.3 286.7 68.1 7.1 0.0 23.8 42.5
69 9176.4 21.5 6.1 216.9 61.3 7.7 0.8 28.3 50.7
53 9163.8 27.4 10.6 291.8 87.7 5.0 0.8 30.0 38.7
26 9152.1 24.1 10.0 275.7 69.8 3.4 1.5 25.3 41.0

 

36

 

 

TABLE 6. cont.
2 9083.1 24.9 10.0 260.6 80.2 3.1 7.1 30.8 36.0
44 9017.3 25.8 11.0 266.0 90.8 10.0 6.9 34.1 32.0
68 9002.7 20.3 6.7 223.8 73.1 3.2 0.3 32.7 44.9
16 8985.5 24.4 9.6 256.3 88.4 9.3 2.4 34.5 35.1
29 8905.9 26.2 10.4 274.9 92.4 11.0 5.8 33.6 35.1
57 8835.8 25.3 11.5 290.7 85.0 10.0 5.9 29.3 35.9
39 8824.5 25.0 9.1 276.8 84.6 8.1 1.1 30.6 42.2
24 8758.2 24.7 10.4 260.8 76.6 7.1 3.5 29.4 35.6
'8 8699.5 25.7 8.5 249.3 77.7 2.3 6.1 31.2 40.2
21 8600.8 25.9 9.3 270.8 89.5 3.9 2.9 33.0 38.9
49 8597.0 23.0 6.8 231.0 79.9 5.4 0.9 34.6 44.6
66 8573.7 21.7 6.6 227.1 75.2 3.5 0.3 33.1 46.1
19 8454.8 23.6 9.5 264.7 96.2 9.7 0.8 36.3 35.6
47 8376.8 24.5 12.4 267.4 91.9 4.9 11.2 34.4 28.2
55 8293.6 28.3 10.3 238.5 86.2 10.1 3.8 36.2 29.7
56 8284.5 25.6 12.0 269.1 86.7 6.7 6.0 32.2 30.5
63 8269.2 22.3 6.4 200.1 62.9 3.4 2.3 31.4 42.6
48 8204.5 23.7 7.3 223.9 78.9 4.2 3.2 35.2 39.9
42 8200.2 24.4 10.8 249.2 81.0 5.2 10.8 32.5 31.1
5 8198.5 27.0 10.3 298.5 85.0 3.0 5.8 28.5 41.6
25 8095.2 26.1 10.9 291.3 102.8 15.9 10.5 35.3 34.5
22 8025.6 25.5 10.0 278.7 88.5 7.1 0.4 31.7 38.0
6 8024.7 26.6 10.6 257.0 78.9 1.7 0.6 30.7 33.7
62 7536.0 27.5 13.8 283.7 84.1 4.7 26.9 29.6 28.9
14 7281.7 25.0 8.7 262.8 79.0 4.4 3.2 30.0 42.3
41 7138.1 26.9 10.4 233.3 73.1 7.0 8.8 31.3 30.9
64 6789.6 22.7 7.0 210.7 68.6 3.7 2.2 32.6 40.4
40 6754.7 22.4 12.1 260.9 87.6 1.2 2.6 33.6 28.7
61 6602.4 27.5 13.5 277.3 72.5 0.0 2.3 26.1 30.3
46 6573.5 25.3 6.5 207.5 75.0 9.2 0.9 36.1 40.7
51 6461.2 25.0 7.4 228.8 81.4 4.8 2.2 35.6 39.8
52 6223.8 25.0 7.8 261.0 78.1 4.6 0.5 29.9 47.0
43 6191.2 24.0 11.5 271.5 88.4 11.2 13.3 32.6 31.9
18 5231.8 22.4 8.6 238.3 80.4 5.7 1.2 33.7 36.5
MEAN 9417.7 24.9 9.5 259.3 81.4 6.3 4.2 31.5 38.4
RANGE 13189.6 29.0 13.8 298.5 102.3 17.1 26.9 40.2 57.4
5231.8 20.3 5.7 200.1 61.3 0.0 0.0 23.8 28.2
LSD 812.5 1.5 1.7 23.1 16.5 14.5 13.2 5.8 7.6
LSDO'01)610.9 1.1 1.3 17.3 12.4 10.9 9.9 4.3 5.7
c.v‘.°°°5) 2.3 1.6 4.8 2.4 5.4 60.9 83.2 4.9 5.3

37

Table 7. Comparison of host Lg! hybrids with 3 best
Commercial chock hybrids.

 

TYPE OF HYBRID

 

 

Characterisics Lfy Commercial check Difference
Grain yield 12614.0 12420.8 193.2
Moisture % 24.8 24.5 0.3
Leaf number 9.4 6.0 3.4
Plant height 260.5 243.4 17.1
Ear height 74.2 91.1 -16.9
Stalk lodging 4.5 4.3 0.2
Root lodging 2.7 1.0 1.7
Ear position 28.5 37.4 -8.9
Shading effect 39.7 50.6 -10.9

 

38

Table 8. Comparison of best L11 hybrids with 5 Commercial
check hybrids.

 

TYPE OF HYBRID

 

 

Characterisics Lfy Commercial check Difference
Grain yield 12614.0 9364.1 3249.9
Moisture % 24.8 21.3 3.5
Leaf number 9.4 6.2 3.2
Plant height 260.5 224.8 35.7
Ear height 74.2 71.3 2.9
Stalk lodging 4.5 4.4 0.1
Root lodging 2.7 0.4 2.4
Ear position 28.5 31.7 -3.2
Shading effect 39.7 49.4 —9.7

 

39

 

 

TABLE 9. VARIETY CORRELATION COEFICIENTS AMONG CHARACTERS OVER
LOCATIONS.
Character 2 3 4 5 6 7 8 9
ns ns ns ns ns ns ns ns
Grain yield -0.078 0.070 0.188 0.021 -0.120 -0.108 -0.l42 0.241
4* *4 4* * *4 a *4
Leaf number --- 0.535 0.730 0.325 0.279 0.415 -0.277 -0.873
** ns ns * ns **
Moisture % --- 0.498 0.225 —0.005 0.239 -0.174 -0.430
** ** ns 4* **
Plant height --- 0.466 0.326 0.215 -0.348 -0.385
4* ns *4 4*
Ear height --- 0.411 0.117 0.664 -0.352
ns ns *
Stalk lodging --- -0.051 0.159 -0.260
ns **
Root lodging --- 0.070 -0.570
ns
EAR POSITION --- -0.040

Shading effect

 

**

It
II II II

ns

highly significant at 0.01% of probability level.
significant at 0.05% of probability level.
non significant at 0.01 and 0.05% of probability level.

40

DISCUSSION

The number of leaves of a determinate species such as
maize is correlated with plant height, flowering date and
grain moisture content at harvest (14,23). The development
of new leaves on the main stalk ceases after the initiation
of the terminal inflorescence. Therefore, earlier induction
of flowering results in fewer leaves, fewer nodes and hence
shorter plants. It appears that within the limits of hybrids
included, that leafy hybrids are tall, late and possess more
leaves above the primary ear (fig. 3,4).

The results herein also elucidate that an increase in
leaf number increases root lodging. This statement confirms
the expectation that higher leaf number above the primary ear
may cause an imbalance of weight of upper and lower parts of
the plant. This imbalance causes the plant to lodge at the
base during wet stormy weather. Root lodging was highly
correlated with leaf number and shading effect (table 9), but
the latter has a negative trend. This implies that lodging
can be decreased either through a decrease of leaf number or
enhancement of photosynthetic activity of the leaves by better
canopy structure (fig.8 and 10). As a matter of fact, leafy
hybrids which have as one of their parents either inbreds 941
Lfy or 371 Lfy are resistant to root lodging. These hybrids
have low ear placement, low shading effect and moderate leaf

number (9-10) above the ear (tables 1 and 6). Similarly, Shaver

41

(73) mentioned the merit of these inbreds in his memmo in 1985
and said "I do recommend using 941 Lfy Inbred as one tester
,....... I think every hybrid having this as one parent can
hardly fail to be beautifully low eared, and have ramrod stiff
stalks". He also indicated that the original lfy 941 was
similar to 371 lfy. In contrast, hybrids originated from
inbred 337Lfy had the highest score of root lodging (Tables

1 and 6). These hybrids were characterize by high leaf number,
high ear position, high shading effect and low yielding. Data
in the literature generally suggest that the reduction of
carbohydrates in the lower portion of the stalk could be
related to a decrease of assimilate supply from the lower
leaves (12,17,52,57). This reduction could be the result of
low photosynthetic activity because of insufficent light
penetration to the lower leaves. However, when the effect of
low carbohydrates is imminent, it may impair the development
of a strong brace-root system which can support the pressure
of the extra leaves above the ear.

Plant and ear height are two other morphological
characteristics which influence the standability of maize. Tall
plants are more susceptible to stalk breakage than short ones,
eSpecially if the ear placement is high. In this study stalk
lodging has a significant positive relationships with both
plant and ear height (table 9). These relationships are weak

and have a negative tendency in non-leafy hybrids. Thus,

42

leafiness and tallness as well as high ear placement together
contribute substantially to stalk lodging in maize (fig. 5,
8, and 9) .

For grain yield the results obtained do not clearly
indicate an apparent relationship between leaf number above
the primary ear and grain yield with a stand density of 55,000
plants per hectare. This correlation would be higher under
more severe competition as a consequence of high plant density.
There are however, several leafy hybrids (36,4,34,30, and 3)
which had high yields. The range of their average yield was
12246.5 to 13189.6 kg/ha. These hybrids came from very
productive leafy inbreds [941 Lfy and (B73Lfy syn.XA25) B73]
which had tall plants with low ear placement, smaller shading
effect and moderate to relatively high leaf number (9-11
leaves) (tables 1 and 6). Furthermore, the prediction equation
of stepwise multiple regression analysis showed that the
combined effects of plant height and shading effect contributed
significantly to the variation in grain yield.

Y = - 2512.0460 + 25.555390 + 146.66910 .

No information has been reported on the correlation
between leaf number and shading effect evaluated as the
distance between two leaves on the same side. Shading effect
has a high negative correlation with leaf number and other
characteristics except yield (table 9). The interpretation of

the relationship between leaf number and shading effect, could

43

be visualized in terms of the efficiency of a maize plant, for
which yield must be considered jointly. In this respect, the
negative coefficients between leaf number and yield and leaf
number and shading effect must be taken into account. They are
indicative (fig. 2 and 7) that the most efficient maize plants
must have higher leaf number above the primary ear and smaller
shading effect (It means a longer distance between leaves on
the same side). This can be achieved by incorporation of leafy
hybrids with the character of upright leaf orientation as
predicted by Duncan et al. in 1967 computer simulation
studies. They found that when LAI of a plant canopy is above
3.5 the vertically oriented leaves would produce a higher
yield than horizontal leaves. Several authors (23,82,27)
reported that upper leaves of the maize plant are the major
contributors of metabolites to the ear and severe shading of
these leaves during the critical period could drastically
decrease the yield. Duncan, W. G. and Hesketh, J. D. 1968
pointed out that vertically oriented leaves above the primary
ear and leaves gradually approaching a horizontal orientation
at the lower portion of the plant would enhance the efficiency
of the leaves and increase grain yield. For example, table (6)
the comparison between lines 61, 62, and 70, 71 demonstrates
typical cases of hybrids which possess high leaf number and
high shading effect and low leaf number and low shading effect.

Numbers 61 and 62 exhibited a combined response to reduce grain

44

yield. The average yield of No. 61 was 6602.4 and No. 62 was
7536.0 kg/ha. No 70 and 71 (71 and 72 are the same pedigree
but for better evaluation was included twice in the study)
since they developed only 6 leaves above the ear, they had
smaller shading effect and thus had an average yield of

11967.1 and 12552.7 kg/ha respectively.

4‘5

 

 

 

 

 

 

 

 

 

46

 

 

 

 

 

 

 

 

 

47

 

 

 

 

 

 

 

 

 

48

Conclusions

Yield of four of the "best" leafy, Lfy, hybrids were
at least equal to the best commercial check hybrids and
significantly better than five of the normal check hybrids.
Moisture content was slightly higher with no real difference
in lodging. Plant and ear heights were similar for the best
selections compared to the two best check hybrids. However,
improvement of shading effect of Lfy hybrids through
incorporation of upright leaf orientation trait may enhance
the efficiency of their photosynthetic surface and therefore
reduce lodging effect.

Many, best not all, of the experimental Lfy hybrids
were later in maturity with considerably more root and stalk
lodging, higher plant and ear height.

Yield differences for Lfy hybrids did not approach
those (30-100%) Obtained in California by Shaver. However,
it is significant that the best experimental Lfy hybrids
produced and tested in the first cycle of breeding in Michigan
were very competitive with commercial hybrids with normal
leaf number.

With a research effort comparable to that devoted
to the development of current commercial hybrids, significant

yield improvement might be obtained with leafy Lfiy germplasm.

49

BIBLIOGRAPHY

1. Abbe, E. C. and B. O. Phinney, 1951, The growth of the
shoot apex in maize: External features. Amer. J. Bot.
38:737-744.

2. Aitken, Y. 1977, Evaluation of maturity genotype-climate
interactions in maize (Zea mays L.), Z. pflanzenzerchtg,
78:216-237.

3. Allison, J. C. 8., Watson, D. J., 1966, The production and
distribution of dry matter in maize after flowering.
Ann. Bot. 30:365-381.

4. , Wilson, J. H. H., and Williams, J. H., 1975,
Effect of defoliation after flowering on changes in
stem and grain mass of closely and widely spaced
maize. Rhod. J. Agic. Res. 13:145-147.

 

5. Arnold, C. Y. 1969 Environmentally induced variations of
sweetcorn characteristics as they relate to the time
required for development J. Am. Soc. hort. Sci. 94:
115-18.

6. Beaughamp, E. G., and Lathwell, D. J., 1966, Effect of
root zone temperatures on corn leaf morphology, can.,
J. plant Sci., 46:593-601.

7. Bonaparte, E. E. N. A., 1975, The effect of temperature,
daylength, soil fertility and soil moisture on leaf
number and duration to tassel emergence in Zea mays
L. Ann. Bot. 38:853-861.

8. , and Brown, R. I. 1975. Leaf number and
maturity studies in Zea mays L. 1. Effects of, and
relationships within, diverse geographic environments.

 

9. , 1977, Diallel analysis of leaf number and
duration to mid-silk in maize. Can. J. Genet. Cytol.

 

19:251-258.

10. Brown, R. H., 1984, Growth of the green plant. In
physiological basis of crop growth and development, ed.
M.B.Tesar. Amer. Soc. Agron. Crop Sci. Amer. Madison,
Wisconsin. pp. 153-174.

11.
12.
13.
14.
15.

16.

17.

18}

19b

20. Duncan, W. G., Williams, W. A., and Loomis, R. S.,

21.

22.

50

Buttery, B. R., and R. I. Buzzell, Maximizing crop

productivity pp. 227-280. Crop Physiology advancing
frontiers, edit. by U.S. Gupta.

Campbell, C. M. 1964, Influence of seed formation of

corn on accumulation of vegetative dry matter and
stalk strength. Crop Sci., 4:31-34.

Carter, M. W., and Poneleit, C. G., 1973 Black layer

maturity and filling period variation among inbred
lines of corn (Zea mays 1.). Crop Sci., 13:436—439.

Chase, S. S., and Nanda, D. R., 1967, Number of leaves
and maturity classification in Zea mays L. Crop Sci.,

7:431-432.

Coligado, M. C., and D. M. Brown, 1975, Response of corn

(Zea mays L.) in the pre-tassel initiation period to
temperature and photoperiod. Agric.Meterol.14:357-367.

Crane, J. C. 1964 Growth substances in fruit setting and

development. Ann. Rev. plant physiol. 15:303-326.

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 Sci., 9:831-834.

, Tanner, J. W., and Duncan, W. G., 1971,

 

Duration of grain filling period and its relation
to grain yield in corn, Zea mays 1. Crop Sci., 11:
45-48 e

, and Kannenberg, L. W., 1976, Relationships

 

between length of actual and effective grain filling
periods and grain yield of corn. Can. J. Plant Sci.,
56:237-242.

1967,
Tassel and productivity of maize. Crop Sci., 7:37-39.

, Loomis, R. 5., Willians, W. A., and Hanau, R.

 

1967, A model for simulating photosynthesis in plant
communities. Hilgardia, 38:181-205

, and J. D, Hesketh, 1968. Net photosynthetic

 

rates, relative leaf growth and leaf number of 22
races of maize grown at eight temperatures. Crop
Sci.,8:670-674.

23.

24.

25.

26.

27.

28.

29.

3o.

31.

32.

33.

34.

51

, 1969, Cultural manipulation for higher yields.

 

p. 327-339. In J. D. Eastin, F. A. Haskins, G.Y.
Sullivan and G.H.M. Van Bavel (eds) Physiological
aspects of crop yield. Am. Soc. Agron., Madison, Wis.

, 1971, Leaf angle, leaf area and canopy

 

photosynthesis. crop Sci. 11:483-485.

, 1975 Maize. In: Crop physiology: some case

 

histories, ed. L. T. vans. Cambridge University Press,
pp. 23-50.

Duvick, D. N., 1951, Development and variation of the
maize endosperm. Ph.D. thesis, Washington University,
cited by Fischer et al. 1984.

Eastin, J. A., 1969, Leaf position and leaf function in
corn-carbon-14 labeled photosynthate distribution in
corn in relation to leaf function. Proc. 24th Ann.
Corn and Sorghum Res. Conf., 81-89.

Eddowes, M., 1969, Physiological studies on competition
in Zea mays L. II. Effect of competition among maize
plants. J. Agric. Sci., Camb. 72:195-202.

Edmeades, G. 0., N. A. Fairey, and T. B. Daynard, 1979,
Influence of plant density on the distribution of
C-Labelled, Can. J. Plant Sci.,

Egharevba, P. N., Horrocks, R. D. and Zuber, M. S. 1976,
Dry matter accumulation in maize in response to
defoliation, Ag. J. 68:40-43.

Eik, K., and Hanway, J. J., 1965, Some factors affecting
development and longevity of leaves of corn. Agron.
J.57:7-12.

Fairey, N. A., and T. B. Daynard, 1978, Assimilate
distribution and utilization in maize, Can. J. Plant
SCi.,58:719-730.

Francis, C. A., Grogan, C. 0., and Sperling, D. W., 1970.
Identification of photoperiod insensitive strains of
maize (Zea mays L.) crop Sci. 9:675-677.

Frey, N. M,. 1981, Dry matter accumulation in kernels of
maize. Crop Sci.,21:118-122.

52

35. Fischer, K. 8., and A. F. E. Palmer, 1984 Tropical maize,
pp.213-248, The physiology of tropical field crops,
ed. by P.R. Goldsworthy, and N.M.Fisher.

36. Goldsworthy, P. R., Palmer, A. E. E., and Sperlig, D. W.,
1974, Growth and yield of lowland tropical maize in
Mexico. J. Agric. Sci. Camb. 83:223-230.

37. Grogan, C. 0., 1956, Detasseling responses in corn.
Agron. J. 48:247-249.

38. Hallauer, A. R., and Russell, W. A., 1962, Estimates of
maturity and its inheritance in maize. Crop Sci., 2:
280-294.

39. Hanway, J. J., 1969, Defoliation effects on different
corn hybrids as influenced by plant population and
stage of development, Ag. J. 61:534-538.

40. , and Russell, W. A., 1969, Dry-matter
accumulation in corn (Zea mays 1.) plants: comparisons
among single-crossed hybrids. Agron. J. 61:947-951.

41. Hesketh, J. D., Chase, 8. S., and Nanda, D. K,. 1969,
Environmental and Genetic modification of leaf number
in maize, and Hungrian millet. crop, Sci., 9:460-463.

42. Hicks, D. R. and Stucker, R. E., 1972, Plant density
effects on grain yield of corbohybrids diverse in
leaf orientation, Agron. S. 64:484-487.

43. Hofstra, G. and C.D. Nelson, 1969, The translocation of
photosynthetically assimilated C in corn, Can. J. Bot.
47:1435-1442.

44. Hunter, R. B., T. B. Daynard, and L. W. Kannenberg, 1969
Effect of tassel removal on grain yield of corn (Zea
mays L.).Crop Sci.,9:405-406.

45. , Hunt, L.A., and Kannenberg, L. W., 1974,
Photoperiod and temperature effects on corn, Can. J.
Plant Sci., 54:71-78.

 

46. , M. Tollenaar, and C. M. Brewr, 1977, Effects
of photoperiod and temperature on vegetative and
reproductive growth of a maize (Zea mays L.) hybrid.
Can. J. Plant Sci., 57:1127-1133.

47.

48.

49.

50.

51.

52.

53.

54.

56.

57.

58.

59.

53

Johnson, D. R., and Tanner, J. W., 1972, Calculation of
the rate and duration of grain filling in corn (zea
mays 1.). Crops Sci., 12:485-486.

Jones, R. J., and Simmons, S. R., 1983, Effect of altered
source-sink ratio on growth of maize kernels, crop
sci. 23:129-134.

Kieselbach, T. A., 1949, The structure and reproduction
of corn. Nebr. Agr. Exp. Sta. Res. Bull. 161.

Lambert, R. J., and Johnson, R. R., 1978, Leaf angle,
tassel morphology, and the performance of maize
hybrids. Crop Sci., 18:499-502.

Langer, R. H. M. 1959, Growth and nutrition of timothy
(Phleum pratense) IV. The effect of nitrogen,
phosphorus and potassium supply on growth during the

Liebhardt, W. C., P. J. Stangel, and T. J. Murdock, 1968.
A mechanism for premature parenchyma breakdown in
corn (Zea mays L.) Agron. J. 60:496-499.

Lorenzoni, C. 1964, Results of a biometric-genetic
analysis of certain characters showing continuous
variation in a cross of Z. mays. Genet. Agra. 18:
435-438.

Mitchell, R. L. 1972 , Crop growth and culture, Iowa
State University press, Ames. 55- Mock, J. J., and
Pearce, R. B., 1975, An ideotype of maize. Euphytica
24: 613-623.

Monteith,J. L.,1965,Light distribution and photosynthesis
in field crops. Ann. Bot. 29:17-37.

Mortimore, C. G., and G. M., Ward, 1964, Root and stalk
rot of corn in South Western Ontario III. Sugar
levels as a measure of plant vigor and resistance.
Can. J. plant Sci. 44:451-457.

Muirhead, Jr. R.C. and D. L. Shaver, 1985, US patent
documents.

Muleba, N. 1976, Physiological responses of three maize
(Zea mays L.) populations to selection for high
yields. A master thesis, Kansas State Univer.
Manhanttan. K.S. USA pp. 13-54.

60.

61.

62.

63.

64.

65.

66.

67.

68.

69.

70.

71.

54

, 1980. Physiological determinants of grain

 

yield of maize (Zea mays L.) varieties in different
environments, Ph.D., thesis, Kansas State University.

Neals, T. F., and Incoll, L. D., 1968, The control of
leaf photosynthesis rate by the level of assimilate
concentration in the leaf: A review of the hypothesis.
Bot. rev. 34:107-125.

Nichiporovich, A. A., 1960 Photosynthesis and the theory
of obtaining high crop yields. An abstract with
commentary by J. N. Black and D. J. Watson. Field
crop abstr. 13:169-175.

Palmer, A. E. E., Heichel, G. H., and Musgrave, R. B.,
1973, Patterns of translocation, respiratory loss,
and redistribution of c in maize labeled after
flowering. Crop Sci., 13:371-376.

Paterniani, E., 1981, Influence of tassel size on ear
placement in maize Mayidica XXVI:85-91.

Pendleton, J. W., G. E. Smith, S .R. Winter, and T. J.
Johnsonton, 1968, Field investigations of the
relationships of leaf angle in corn to grain yield
and apparent photosynthesis. Agron. J. 60:422-424.

Pendleton, D. E., and Hammond, J. J., 1969, Relative
photosynthetic potential for grain yield of various
crop canopy levels of corn. Agron. J. 61:911-913.

Pepper, G. E., Pearce, R. B., and Mock, J. J., 1977,
Leaf orientation and yield of maize, crorp sci., 17:
883-886.

Russell, W. A., 1972, Effect of leaf angle and hybrid
performance in maize, crop sci. 12:90-92.

Shannon, J. C., 1974, In vitro incorporation of carbon-
14 into Zea mays 1. starch granules. Cereal Chem.,
51:798-809.

Shaver,D.L. 1983. Genetics and Breeding of maize with
extra leaves above the ear. Proc. 38th Ann. Corn and
Sorghum Res. Conference: 161-180.

, 1986. Memorandum to leafy subscribers pp.

 

1-4.

72.

73.

74.

75.

76.

77.

78.

79.

80.

81.

82.

83.

84.

55

, 3-12-1985, The extra-leaf trait and the case

 

for doubling corn yields, 1-13.

, 8-16-1985, Memorandum to leafy subscribers

 

pp.1-7.
, 1986 d Memorandum to leafy subscribers pp.

 

1-2.

, 2-24-1986, Memorandum to leafy subscribers

 

pp.1-7.

Shaw, R. H., and Thom, H. C. S., 1951, On the phenology
of field corn., silking to maturity. Agron. J. 43:
541-546.

Stein, 0. L. 1956, A comparison of embryonic growth rates
in two inbreds of Zea mays L. Growth, 20:37-50.

Stinson, H. T., and Moss, D. N., 1960, Some effects of
shade upon corn hybrids tolerant and intolerant of
dense planting. Agron. J. 52:482-484.

Thorne, G. N., and D. J. Watson, 1955, The effect on
yield and leaf area of wheat of applying nitrogen as
a top dressing in April or in sprays at ear emergence.
J. Agr. Sci, 46:449-456.

Tollenaar, M. 1977, Sink-source relationships during
reproductive development in maize a review, Maydica
XXII:49-75.

, and Daynard, T. B., 1978, Kernel growth
and development at two positions on the ear of maize,
con. J. Plant, Sci., 58:189-197.

 

Tripathy, P. C., Eastin, J. A., and Schrader, L. E., 1972,
A comparison of C-labeled photosynthate export from
two leaf positions in a corn (Zea mays 1.) canopy.
Crop Sci., 12:495-497.

Whigham, D. K. and Woolley, D. G., 1974, Effect of leaf
orientation, leaf area, and plant densities on corn
production, Aug. J. 66:482-486.

Williams, W. A., Loomis, R. S., and Lepley, C. R., 1965,
Vegetative growth of corn as affected by population
density. II. Components of growth, net assimilation
rate and leaf areas index. Crop Sci., 5:215-219.

56

85. , R. S. Loomis, W. G. Duncan, A. Dovrat, and
F. Nunez A., 1968, Canopy architecture at various
population densities and the growth and grain yield
of corn. Crop Sci., 8:303-308.

86. Wilson, J. H., M. St. J. Clowes, and J. C. S. Allison,
1973 Growth and yield of maize at different altitudes

APPENDIX

57

Table 10. MEAN SQUARES PROM ANALYSIS OF VARIANCE OF DATA
COLLECTED IN CASS COUNTY IN 1986.

Source of variation

 

Total Replications Hybrids block (adj.) Error

 

D.F. 143 1 71 16 71 or 55

Grain yield 139065.20 6723387.28** ---- 110825.40
Moisture % 0.06 8.98** ---- 0.42
Leaf number 0.08 8.34** ---- 0.45
Plant height 1681.04 1198.53** 149.90 51.47
Ear height 785.61 240.06** 68.09 31.26
Stalk lodging 29.19 106.27** 93.05 53.46
root lodging 0.04 182.86** 76.50 53.26
Ear position 31.65 26.09** 4.98 3.77
Shading effect 16.41 93.78** ---- 7.70

 

** = significant at 0.01% of probability level.

* = significant at 0.05% of probability level.

1/ = 71 and 55 are D.F. of the Error term for Randomized
Complete Block Design and Lattice Design respectevely.

58

Table 11. MEAN SQUARES PROM ANALYSIS OF VARIANCE OF DATA
COLLECTED IN SAGINAI COUNTY IN 1986.

Source of variation

 

Total Replications Hybrids block (adj.) Error

 

1/
D.F. 143 1 71 16 71 or 55

Grain yield 198664.65 7386360.93** 28877.10 83399.21

 

Moisture % 0.13 8.23** 0.30 0.20
Leaf number 1.90 7.32** 0.45 0.38
Plant height 116.29 888.42** 225.30 98.82
Ear height 1.13 141.02** ---- 44.03
Stalk lodging 18.45 11.54** 9.74 5.79
root lodging 1.43 3.69* ---- 2.47
Ear position 5.52 21.70** ---- 5.51
Shading effect 15.12 76.57** ---- 8.87
** = significant at 0.01% of probability level.

* = significant at 0.05% Of probability level.

1/ = 71 and 55 are D.F. of the Error term for Randomized

Complete Block Design and Lattice Design respectively.

59

TABLE 12. MEAN SQUARES FROM COMBINED ANALYSIS OF VARIANCES
FOR VARIOUS CHARACTERS.

 

source Of variance

 

 

 

Location Hybrid Loc x Hyb
Grain yield 38.56** 11.80** 11.66**
Leaf number 8.52** 34.27** 1.06ns
Moisture % 99.37** 3.29** 12.54**
Plant height 391.92** 21.22** 1.10ns
Ear height 85.55** 4.62** 1.68**
Stalk lodging 122.97** 3.19** 0.51ns
Root lodging 122.18** 1.28ns 2.80**
Ear position 0.09ns 5.49** 1.54**
Shading effect 45.29** 18.71** 1.01ns
** = highly significant at 0.01% of probability level.
* = significant at 0.05% of probability level.
ns = non significant at 0.01 and 0.05% of probability levels.

60

 

 

TABLE 13. CORRELATION COEFICIENTS AMONG CHARACTERS IN CASS County
Character 2 3 4 5 6 7 8 9
ns ns ns ns ns ns ns ns
Grain yield 0.033 0.030 0.226 0.104 -0.101 -0.010 -0.500 0.076
** ** * * ** ns **
Leaf number --- 0.475 0.648 0.266 0.234 0.470 -0.174 -0.868
** ns ns * ns **
Moisture % --- 0.452 0.102 -0.049 0.268 -0.204 -0.322
** * ns ns *
Plant height --- 0.486 0.244 0.201 -0.172 -0.298
** ns *4 *4
Ear height --— 0.333 0.110 0.774 -0.321
ns ns *
Stalk lodging --- 0.008 0.184 -0.246
n8 **
Root lodging --- -0.025 -0.442
ns
EAR POSITION --- -0.140

Shading effect

 

**

a.
II II II

HS

highly significant at 0.01% of probability level.
significant at 0.05% of probability level.
non significant at 0.01 and 0.05% of probability levels.

TABLE 14. CORRELATION COEFICIENTS AMONG CHARACTERS IN SAGINA' County.

61

 

 

Character 2 3 4 5 6 7 8 9
ns ns ns ns ns ns ns **

Grain yield -0.189 0.011 0.081 -0.065 -0.116 -0.150 -0.132 0.340
4* ** ns ns * ** *4

Leaf number --- 0.426 0.685 0.217 0.164 0.287 -0.303 -0.838
** ns ns ** ns **

Moisture % --- 0.342 0.138 -0.029 0.308 -0.121 -0.355
** * ns ** *

Plant height --- 0.414 0.273 0.183 -0.335 -0.269
n5 * ** *

Ear height --- 0.021 0.238 0.716 -0.256
ns ns ns

Stalk lodging --- 0.058 -0.171 -0.015
ns *

Root lodging --- 0.100 -0.273
ns

EAR POSITION --- -0.054

Shading effect

 

**

I-
II II II

HS

highly significant at 0.01% of probability level.
significant at 0.05% of probability level.
non significant at 0.01 and 0.05% of probability levels.

62

1am

”I

 

 

am) nutm-
‘F ‘P
MIN“

I}!

 

'1. Wu

pm
JV!

 

 

 

not
mnfi‘fim
0! '3'? T ’f

 

63

 

 

 

 

 

 

 

 

64

 

 

 

 

.R.

a!”
$.32 m. h .FS m.
figs-agai-

 

 

 

 

 

.EINNFFS!
:83!-

:92. saga-......

 

 

 

NEEFF

ragga:

65

 

 

1.3 u... or or. at at £6
3.»... 1821269.. 8. 13. .19»

  

 

 

S.
N1 a .1 0
ea eee‘ ea
M'l e a e as a van 0
w eee‘e I see
... . . ”a .
a .. .
u. a. a. .r a. ... ...

HS.» in; aisv
...... 148.889.... ......

 

 

 

Mgmhn)
I I

 

 

 

.e 1. er a? a? Lalo...
nahieiaaas
.2. .eaaguflza .3.

66

 

 

 

 

 

 

 

 

 

 

no 9 Thus“. "I a. u
.... u * .M at we
as... .213 3

Salas-“#:2233966:

 

67

 

 

 

  
 

as... a one see-
5 e e e aeo“e a. e
.5 w. E I H E

 

 

Sun. 26%.... use!

 

 

 

IIIIIIIIIIIIII