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THE EFFECT OF GLUME PEGMENTATION
ON THE PQST-HARVES‘T DORMANCY OF
COMMON WHEAT; TMFICUM AESTIVUM .l_.._

 

The“: {or ”1:. Degree 0' M. 5.
MICHIGAN STATE UNIVERSITY
Bahman Ehdaie

£968

 

 

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THEE-5‘5

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ABSTRACT

THE EFFECT OF GLUME PIGMENTATION ON THE POST-HARVEST
DORMANCY OF COMMON WHEAT, Triticum aestivum L,

by Bahman Ehdaie

The lines used in these studies were derived from a back-
cross population.

Genesee, a white seeded-red glumed nondormant variety was
used as a recurrent parent and Redcoat, a red seeded-white
glumed dormant variety was used as a donor parent. Both
threshed and unthreshed seeds were used in these studies.

The effect of a low germination temperature for breaking
dormancy of threshed seedwas highly significant while it was
nonsignificant for unthreshed seed.

The period of post-harvest dormancy of threshed seeds was
much shorter than that of unthreshed seeds. These differences
were due to the presence of latent factors in the glumes which
directly or indirectly suppressed germination.

Analysis of variance showed that white glumes had more
latent factors than did red glumes, in the eight pairs of lines

studied in this experiment.

THE EFFECT OF GLUME PIGMENTATION ON THE POST-HARVEST
DORMANCY OF COMMON WHEAT, Triticum aestivum L,

 

By

Bahman Ehdaie

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of CrOp Science

1968

ACKNOWLEDGMENTS

The author wishes to express his sincere appreciation to
Dr. E. H. Everson for his help and guidance throughout this
study.

Thanks are due also to Drs. C. E. Cress and C. M.
Harrison for their critical appraisal of the manuscript.

The author also wishes to acknowledge the assistance of
his wife with the many chores associated with the study.

Appreciation is expressed to the Government of Iran for

financial support during the course of this study.

TABLE OF CONTENTS

Page
Acknowledgement. . . . . . . . . . . . . . . . . ii
List of Tables . . . . . . . . . . . . . . . . . iv
List of Appendicies. . . . . . . . . . . . . . . v
Introduction . . . . . . . . . . . . . . . . . . 1
Review of Literature . . .’. . . . . . . . . . . 2
Inheritance of Dormancy in Wheat . . . . . . 8

Inheritance of Seedcoat Pigmentation in
Wheat. 0 O O O O C O 0 O O O O O O O C O 0 0 ‘0

Inheritance of Glume Pigmentation in Wheat . l0
Materials and Methods. . . . . . . . . . . . . . lZ
Threshed Seed Test . . . . . . . . . . . . . 12
Unthreshed Seed Test . . . . . . . . . . . . 13
Experimental Results . . . . . . . . . . . . . . 20
Discussion and Conclusion. . . . . . . . . . . . 25
References Cited . . . . . . . . . . . . . . . . 28
Appendix A . . . . . . . . . . . . . . . . . . . 32
Appendix B . . . . . . . . . . . . . . . . . . . 39

LIST OF TABLES

Table Page

I Germination of 27 freshly harvest, I966

greenhouse grown Genesee 2x Redcoat,

F7 lines . . . . . . . . . . . . . . . . . . l6
2 Paired lines of l966 greenhouse grown

dormancy lines with their properties and

tendency for sprouting . . . . . . . . . . . l8
3 Scaled data (means) of the germination test

on threshed seed of I966 field grown
dormancy lines with red seed but either
red or white glumes. . . . . . . . . . . . . l9

A Scaled data (means) of the germination
test on unthreshed seed of I966 field grown
dormancy lines with red seed but either
red or white glumes. . . . . . . . . . . . . 23

iv

Appendix A

a

Appendix B

a

LIST OF APPENDICIES

Analysis of variance of the threshed
seed germination data in Table 3 . .

Examination of the temperature x pair
interaction (T. x P.) for the data of
Table 3. O O O O O I O O O O O O O 0

Examination of the temperature x glume
color interaction (T. x Gc.) of the data
of Table 3 . . . . . . . . . . . . . .

Examination of the pair x glume color
interaction (P. x Gc.) for the data of
Table 30 O O O O O O O O C I O O O C O 0

Examination of the pair x glume color
interaction (P. x CC.) for IOC. for
the data of Table 3. . . . . . . . . .

Examination of the pair x glume color
interaction (P. x Gc.) for 20C. for
the data of Table 3. . . . . . . . . .

Analysis of variance of the unthreshed
seed germination data in Table A . .

Examination of the temperature x pair
interaction (T. x P.) of the data
0‘F Table LE 0 O O O O O C O O O 0 O 0

Examination of the temperature x glume
color interaction (T. x Gc.) of the
data of Table 4. . . . . . .

Page

33

34

35

36

37

38

40

Al

#2

REVIEW OF LITERATURE

Dormancy of seeds is manifested by a delay in germination
or no germination when held under favorable germinating
conditions. Crocker (I916) described the mechanisms by which
seeds may be delayed in germination as follows:

(a) Rudimentary or immature embryo.
(b) Complete inhibition of water absorption by
surrounding structures.
(c) Mechanical resistance to the expansion of the
embryo by enclosing structures.
(d) Inhibition of gas exchange by enveloping
structures.
(e) Failure of embryo to grow.
(f) Assumption of secondary dormancy.
Dormancy in the seed could also be due to the presence of
substances with germination-inhibiting prOperties.

Link and Walker (I933) isolated substances from pigmented
onion scales which retarted the growth of some onion diseases.
Cox et al. (I945) reported the existence of a germination inhibitor
in the seedcoat of certain varieties of cabbage.

Smith (I948) observed that aqueous solutions of wheat chaff
were sometimes, but not consistently, effective in inhibiting

seed germination. Elliott and LeOpold (I953) found that the

INTRODUCTION

Seed from unthreshed heads of common wheat varieties has
usually demonstrated greater post-harvest dormancy than
comparable threshed seed.

Aqueous extracts of wheat chaff (Smith, I948) were
sometimes, but not consistently, effective in inhibiting seed
germination. Numerous papers report the association of wheat
seedcoat pigmentation and post-harvest dormancy. Miyamoto et al.
(196]) reported the isolation of a dormancy factor from a red
wheat variety. This study will attempt to answer the question
as to whether or not there is a dormancy factor in the glumes
associated with pigmentation which would Operate independently

of seed dormancy.

hulls from seeds of Avena sativa contain substances which suppress

 

germination. Nagao et al. (I957) reported on an association of
seedcoat pigmentation with some germination inhibitors in red and
brown rice varieties. Black (I959) demonstrated the existence
of some germination retarding agents in the seeds of wild oats.

Many investigators (Lomejko I937 - Wellington I956 -
Everson and Hart l96l - Belderok I96l - and others) have shown
that red-grained varieties of wheat are more resistant to
unfavorable climatic conditions than white-grained ones.

Variation in the tendency to sprout has been observed
among red-grained varieties but very little variation has been
recognized among white-grained ones.

Wellington (I956, a.b.) stated that the mechanical
properties of the covering layers are responsible for the
condition of post-harvest dormancy in wheat seed. The outer
layers of the wheat grain during shrinkage is thrown into
folds over the dorsal region of the seed where the embryo is
located, whereas in the red grain both outer and inner layers
contract simultaneously and no folding takes place. The
behavior of the epidermis in the two seeds at this stage of
maturation indicated a difference in its mechanical properties

which may subsequently affect the expansion of the embryo.

While in white grain the folded epidermis proves no impediment
to the expansion of the embryo, in red grain no expansion
can take place without devel0ping tension in the epidermis.
Wellington also believed that the osmatic value of embryonic
cells increases either by the transporation of carbohydrates
from the endosperm to the embryonic cells or by the hydro-
lization of the starch present in the embryo. These ideas
are supported by two facts. First, breaking the seed coat
of the dormant grain at the distal end promotes germination
by facilitating the transportation of carbohydrate from the
endosperm to the embryo. Second, desiccating the dormant
grain stimulates germination by hydrolyzing the starch present
in the embryo.

Belderok (l96l) recalls Tetyurev who suggested the
embryonic appendage as one of the most important obstacles
to the germination of wheat. Tetyurev thought that the
oxygen transport to the interior of the grain depended to
a great extent on the embryonic appendage and its mucilaginous
pr0perties. As soon as water reached these mucilaginous cells
they swelled and prevented oxygen from reaching the embryo
through the micrOpyle. If dry, warm weather prevails during
the maturation processes, the behavior of the embryonic

appendage changes due to less swelling.

Thus, oxygen penetration and carbon dioxide eleimination
was permitted and dormancy terminated.

This suggestion is substantiated by the fact that wheat
seeds are more prone to sprouting if they are exposed to
dry, hot weather during maturation rather than to wet and
cold.

Mosheov (I938) was the first investigator to study the
influence of the water extract of wheat grain upon germination
and growth. The germination of a sample of nondormant wheat
seeds was inhibited for several days when soaked in a water
extract of dormant wheat seeds. The inhibitory action of the
wheat extract, however, was eliminated by heating.

Miyamoto and Everson (I958) studied the biochemical and
physiological aspects of wheat seed pigmentation. They
illustrated an association of seedcoat pigmentation and some
germination inhibitors. As the quantity of the kernel
pigmentation precursors were increased the degree of seedcoat
color also increased. They concluded that the condition of
dormancy in red wheat seed is apparently due to the existence
of germination suppressing substances in the seedcoat. However,
these inhibitors were water soluble. Similar germination
suppressors were found in the seedcoat of red and brown rice

by Nagao et aI. (I957).

In l96l, Miyamoto et al. conducted another experiment
on the dormancy of wheat seed. Four inhibitory fractions
were extracted from the red seedcoat. In addition to showing
germination inhibitors in the red seedcoat, they demonstrated
that post-harvest dormancy was not caused either through
water restriction, gas exchange, or an immature embryo. The
loss of post-harvest dormancy was explained as inactivation
of the inhibitors located in the seedcoat. Ching and Foote
(l96l) carried out an experiment on the post-harvest dormancy
of several wheat varieties considerably different in rates
of germination. They demonstrated that covering layers were
neither the barriers for gas exchange nor amount of water
uptake in dormant and nondormant wheat seeds. Since the
water extract of dormant seeds retarded the germination of
nondormant seeds, they concluded that delayed germination of
dormant seeds was due to the presence of inhibitors in the
seeds, probably located in the seedcoat. They stated that
the growth inhibitors were oxidized more readily at high
temperature and thus lowered dormancy compared to low temperature.
This is why post-harvest dormancy could be kept in the seeds
if they were stored in a cool place. They also assumed that

the overcoming of post-harvest dormancy by a low germination

temperature could be due to synthesis of new substances in
the seed which stimulated germination.

Belderok (l96l) found that the amount of water available
to the wheat plants and the relative humidity of the
atmosphere before harvesting were not involved in determination
of post-harvest dormancy. Temperature during the stage of
mealy-ripeness was considered by Belderok to be the most
important climatic factor in determination of post-harvest
dormancy. A negative correlation was found between temperature
at this stage of maturation and the duration of post-harvest
dormancy. He also illustrated the occurrence of some chemical
compounds with oxygen absorbing prOperties in the covering
layers. Positive correlation was found between the quantity
of these substances and postmharvest dormancy. Belderok
(I965) suggested temperature-sum as an index for determination
of duration of post-harvest dormancy in wheat seed. The
temperature-sum is obtained by multiplying the period of
meaIy-ripeness (days) by the excess of temperature above l2.5C.
during this period. The duration of post-harvest dormancy is
in a reverse relation to the temperature-sum.

Harrington (I932), Harrington and Knowles (I940),
Hutchinson et al. (I948), Harrington (I949), Wellington and

Durham (I958), and Everson and Hart (l96l) have demonstrated
greater post-harvest dormancy of unthreshed wheat seed than
of comparable threshed seed. These differences may be due
to a stimulating action of some compounds in the glume on
some latent factor within the grain itself or competition
between glumes and the grain for free moisture. In the case
of ample water, thin layers of water between the glumes and
kernel may obstruct gas exchange. Smith (I948) believed the
lower germination of unthreshed seeds of certain varieties
of wheat was neither due to lack of water nor oxygen reaching
the embryo. He noticed that the aqueous extract of wheat
chaff, sometimes but not consistently, was effective in

suppressing seed germination.

Inheritance of Dormancy in Wheat
Nilson-Ehle (l9l4) was the first scientist to pay
attention to the phendmenon of dormancy in wheat seed. The
conclusions of Nilson-Ehle according to Lomejko (I937) are:
l. The dormancy characteristic is an inherited
trait.
2. This character is independent of the character

of earliness and winter hardiness.

3. Several genes are involved in the dormancy
characteristic.
4. Among these genes those that distinguish
the degree of pigmentation play an important
role in dormancy.
5. Varieties with all the genes for red color
germinate slowest while those without any
gene, white grain, germinate the quickest.
Hutchineson et al. (I948) recalls gkerman and Feekes who
confirmed the observation of Nilson-Ehle and considered a
genetic linkage between the factors for redness and resistance
to sprouting. Muller (I964) found that sprouting occurred in
the F] as readily as in one of the parents, the susceptible
one. The correlation value between selected resistant
descendants in the F2 generation was 0.l2. Thus, Muller
declared that the phenomenon of sprouting was controlled
polygenetically, and selection in the F2 was not effective.
A higher correlation value, r = 0.38, was obtained between
selected F3 parents and their descendants. From Everson and
Hart's (l96l) experiment one could speculate that one or more
of the three pairs of genes for kernel pigmentation are
partially responsible for resistance to kernel sprouting in

wheat.

IO

Inheritance of Seedcoat Pigmentation in Wheat

According to Percival (l92l), Nilson-Ehle found that
three similar pairs of dominant genes control wheat grain
pigmentation. These genes were not linked. The genotype
containing all three pairs of these dominant genes is
designated by R1R1R2R2R3R3. The effect of these genes is
cumulative. Therefore, an F2 plant may have any number of
such genes ranging from one to six. Thus, seven different
homozygous heritable degrees of intensity of color are
possible. However, environmental factors such as temperature,
light, etc., also affect the intensity of the color.

Everson and Hart (l96l) stated that the genes causing
dormancy must be cojoined with only one, or two, but not
all, of the genes for seedcoat pigmentation, since the
association between the red seedcoat characteristic in wheat
and dormancy is not a complete one. Which heritable
association, linkage or pleotropic, exists between seedcoat

color and dormancy has not yet been determined.

Inheritance of Glume Pigmentation in Wheat
The colors of the glumes, lemma and palea, in wheat are
generally described as some shades of black, red, or white.

The red color contains various shades of brown and red. The

ll

white color embraces numerous shades of yellowish-white.
Black and red color, are according to the numerous crosses,
more or less dominant over white, and black also masks the
red tins (Percival, l92l).

In some crosses between black-glumed varieties and red-
glumed ones the appearance of several individuals with the
white-glumed characteristic has been reported in the F2
generation (Keyzer and Boyack, l9l8). Similar observations
have been shown between crosses of red-glumed varieties.
Intermediate individuals, from the point of view of glume
color, may be obtained among F] and F2 individuals from
crosses between red- and white-glumed varieties.

According to Percival (l92l), Nelson-Ehle has reported
a l5 red to I white segregation in the F2 generation of some
crosses made between white- and red-glumed varieties. The
intensity of red color produced by the two genes was not the
same. These dominant genes were recognized to have additive
or cumulative effects. It was believed that pigmentation
was fully developed only in seasons which were hot, dry and

bright.

MATERIALS AND METHODS

A cross was made between a nondormant - white seeded -
red glumed variety, Genesee, and a dormant - red seeded -
white glumed variety, Redcoat.

At harvest, seed of individual F2 plants were germinated
using methods described by Everson and Hart (l96l), and
selections exhibiting seed dormancy were isolated. The F3
progeny of the dormant lines were rechecked for dormancy and
the dormant lines were again crossed to Genesee. This
backcross p0pulation was selfed for 6 generations, selecting
for dormancy in the F3—F6 generations.

Twenty-three dormant F7 lines from the backcross

2 x Redcoat were grown both in the greenhouse (in

Genesee
I0-I2 cm pots) and the field (in l-l.5 m head rows) during

the l965-l966 season. Dormancy was determined by germination
tests employing both threshed and unthreshed seed, the latter

to determine the effect of the glumes on germination.

Threshed Seed Test

 

In the test on greenhouse grown threshed seed, 50 seeds
of each line and the Genesee check were chosen and placed on

a 9cm x I3cm folded germination blotter presoaked in a I/2oo,ooo

IZ

l3

solution of panogen to control mold. The moisture content
of the seeds at harvest was below l4 percent. The blotters
were placed in wooden flats containing 5cm of wet sand and
the flats covered with polyethylene plastic, held in place
by a heavy rubber band to maintain humidity. Each flat
contained a Genesee check. The test temperature was held at
24 C. Each sample was read at 5, 7, l0, l2, I5, and I9-
day intervals.

From each line selected from the greenhouse material5 head
rows were pflanted in the field and a sample of 25 seeds
from each row was tested for germination. The field grown
lines were tested at l0 C. and 24 C. in darkness. The flats
contained both Genesee and Redcoat as checks. The samples
were watered each day throughout the study. Daily germination
readings were recorded for each sample. In the threshed seed
test, the seed was considered germinated when the seedcoat
over the embryo Split due to swelling of the embryo. When
40 percent or more of the seeds germinated, the sample was

considered germinated.

Unthreshed Seed Test
In the greenhouse study 5 heads of each line were tested

to determine the effect of glumes on germination. The heads

l4

were randomly chosen and placed in a wooden flat containing
50m of moist sand. Five heads of Genesee were used in each
flat as a check. The flats were covered and watered as
described above. Test temperature was 24 C. Readings were
made at 5, 7, IO, I2, l5, and l9-day intervals. A head was
considered germinated when rootlets or coleoptiles from 3
seeds were visible. In the study of field grown materials
3 heads from each of the 5 head rows were germinated.
Germination readings were taken daily. The study was run
at I0 C. and 24 C. in darkness. The flat contained both
Genesee and Redcoat as checks.

After the results of the dormancy test on greenhouse
grown seed were obtained, 8 lines with red glumes were
paired with 8 lines with white glumes on the basis of similar
threshed seed dormancy. With the field grown materials both
the threshed and unthreshed seeds were used in a paired
comparison replicated experiment utilizing the same 8 pairs.

The pairing process was done to investigate the effect
of glume pigmentation on germination.

A split-plot design with temperature as the whole plot
and pair of lines as the subplot was employed to analyze

the data obtained from the field study.

l5

To apply the analysis of variance procedure to the
results of the field study, the data was scaled as below to
favor the lines with higher dormancy:
Threshed seed which germinated after 2, 3, 4, 5,
6, 7, or 8 days received a value of l, l, 2,
4, 6, 9, or l2, respectively.

Unthreshed heads germinating after 3, 4, 5, 6, 7,
8, 9, or ID days received values of I, l, 2,

4, 6, 9, l2, or l5, respectively.

By this scaling a subsample of the threshed seed may receive

a minimum value of l to a maximum value of l2 and a sample
from 5 to 60. In the unthreshed test a subsample may have

a value as low as I and as high as l5 and a sample from

5 to 75.

7

Germination of 27 freshly harvested, I966 greenhouse grown Genesee 2x Redcoat,
lines which varied for glume color and post-harvest dormancy and the
check variety Genesee

F

Table I.

Threshed Seedi Unthreshed Seed

Seed-
Coat

RowTNo.

 

Day

 

Glume
Color

I966
Greenhouse

l5

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I9

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dormancy

Table 3. Scaled data (means) of the germination test on
threshed seed of I966 field grown dormancy lines
with red seed but either red or white glumes

'RepTication I ‘Replication II
Pair Glume Temperature TemperatUre
Color of
Line 20C. IOC. 20C. IOC.
p] white I.2+ I.2 l.8. 2.0
red l.8 l.0 2.8 2.4
pg white 2.0 I.0 3.2 2.0
red 8.2 I.2 7.8 2.4
p3 white 2.8 I.0 3.2 2.0
red 6.4 1.0 8.8 2.0
pg white 2.0 l.0 2.4 2.0
red I.2 I.0 l.6 2.0
ps white 4.4 l.4 5.6 2.0
red 2.6 I.2 2.4 2.0
p6 white 5.6 I.2 9.2 2.0
red l0.8 l.6 l2.0 2.0
p7 white 5.2 I.2 8.2 2.0
red ll.4 2.0 l2.0 2.0
p8 white 9.6 1.6 12.0 2.4
red 6.8 l.6 l0.8 2.0
+ Low values indicate less dormancy - high values more

EXPERIMENTAL RESULTS

The results of the germination test of the 27 greenhouse

grown Genesee 2

x Redcoat F7 lines which varied for glume
color and post-harvest dormancy are shown in Table I. On
the basis of different glume color and similar germination
values of threshed seed, lines Ill-I35, l37-l26, ll8-l30,
ll9-ll3, l23-Il2, l24-I40, l25-I38, and l32-l34 were paired.
The paired lines and their respective germination data are
given in Table 2. Red and white glume lines in a pair had
very similar threshed seed germination. Differences in
germination between paired lines existed in the unthreshed
seed tests but since these were not replicated no valid
conclusions could be drawn. Table 3 presents the scaled data
of the germination test on threshed seed from the I966 field
grown dormancy lines. These lines all had red seed but the
lines of a pair differed in glume color.

An analysis of variance of this data (Appendix A,
Table a) showed the differences between the following treatments
and interaction were highly significant: temperature, pair,

temperature x pair, glume color (glume was not present: in

this test but the term used to designate the lines of a pair),

20

2l

temperature x glume color, pair x glume color, and temperature
x pair x glume color.

The dormancy of threshed seeds was lowered by lowigemmination
temperature. However, two pairs, I and 4, showed similar
responses in terms of germination rate to both high and
low temperature (Appendix A, Table b). One could say that
there was little if any dormancy in the seeds of these two
pairs to be broken by low temperature. Highly significant
differences in rate of germination among the pairs were
expected since the selected pairs previously exhibited
different germination values. Nonsignificant results for
glume color were expected since the lines were paired on the
basis of similarities in their germination rates but it
appeared to be highly significant (Appendix A, Table a).
However, this discrepancy could be contributed to the year
to year variation or to insufficient evidence for pairing
processes. The initial data which was used for determining
the pairing relationship was from an unreplicated test.

The significant result, however, indicates that those
seeds which developed and matured in red glumes had more

dormancy than those with white glumes.

22

Examination of the pair x glume color interaction
(Appendix A, Table d) showed that in pairs 5 and 8 the seeds
which were enclosed in white glumes had more dormancy than
those which were surrounded with red glumes. In pairs 2, 3,
6, and 7 the Opposite situation was found. In pairs l and
4 no differences in rate of germination were found between
the two sets of seed, over all temperatures.

Interaction between temperature and glume color (Appendix
A, Table c) showed that regardless of glume color a low
germination temperature could terminate the state of
dormancy over all pairs. Examination of the three factor
interaction, (Appendix A, Tables e and f) indicated that in
all the pairs seeds deveIOped in red or white glumes had lost
their dormancy when they were subjected to a low germination
temperature. When they were subjected to a high germination
temperature some of the seeds deveIOped in red glumes showed
more post-harvest dormancy than those deveIOped in white
glumes.

Table 4 presents the scaled data of the germination test
on unthreshed seed of the I966 field grown lines. These lines

all had red seed but the lines of a pair varied in glume color.

 

23

Table 4. Scaled data (means) of the germination test on
unthreshed seed of I966 field grown dormancy
lines with red seed but either red or white glumes

 

 

 

ReplTCation | *—RepTication'TT “““
Pair Glume Temperature Temperature
Color of
line 20C. ,, IOC. 20C. IOC.
p] white 5.200*' 7.733 5.066 8.333
red ll.533 8.266 8.800 9.800
p2 white 13.200 7.200 15.000 10.400
red l2.666 6.800 l4.600 9.000
p3 white 6.666 7.800 13.000 9.400
red 8.400 6.800 l4.000 9.000
p4 white 5.933 5.733 I3.000 9.200
red 3.000 9.000 4.000 9.600
p5 white 5.133 6.133 14.200 9.800
red 4.200 7.200 4.933 I0.000
p6 white 9.866 8.000 14.400 9.600
red ll.333 9.733 I5.000 lI.OOO
p7 white 4.000 9.000 6.733 l0.200
red 4.l33 l0.200 l3.800 ll.800
p8 white I0.200 7.400 l4.000 9.200
red 4.800 8.800 l3.8OO 9.400

 

‘* Low values indicate less dormancy - higher values
more dormancy

24

In this germination test the seed was enclosed by glumes
throughout the study. An analysis of variance of this data
(Appendix B, Table a) showed the differences between the
pairs and temperature x pair were highly significant and
temperature x glume color interaction was significant.

No significant differences in glume color were found in
rate of germination of the seeds under the high and low
temperature. However, examination of temperature x pair
interaction (Appendix B, Table b) pointed out that dormancy
was significantly lower only in pairs 2 and 6 when the
germination temperature was low. Highly significant
differences in germination rate among the pairs were expected.
No meaningful differences were found between germination rate
of seeds with white glumes and those with red glumes.
Inspection of temperature x glume color, (Appendix B,

Table c) showed that post-harvest dormancy of the seeds
enclosed in white glumes was broken at low germination
temperature while no differences were observed in the
germination rates of the seeds enclosed in red glumes when

they were subjected to the high and low germination temperature.

DISCUSSION AND CONCLUSION

Comparisons between the results obtained from germination
tests of the threshed and unthreshed seed show that the
period of post-harvest dormancy for unthreshed seeds was
longer than comparable threshed seed. Two groups of seeds
were characterized in the threshed seed tests, namely those
with red glumes and those with white. The latter group
showed much less post-harvest dormancy than the former.
However, in the unthreshed seed test, when glumes were
present with the seeds, no differences in post-harvest
dormancy were found between the two groups.

The theory that dormancy was induced by an oxygen
deficiency due to presence of microorganisms under the glumes
did not seem entirely accurate since microbial growth was
controlled by applying panogen to the water.

There remains the theory of the existence of germination
inhibitors in the glumes which directly suppress seed
germination for a certain period or the presence of some latent
factors which indirectly inhibit seed germination by
stimulating some factors in the seed to become inhibitors

(Hutchinson et al., I948).

25

26

This theory arose from the observation that the rate
of seed germination was significantly reduced from threshed
to unthreshed seed. In this experiment it also seems likely
that there are more inhibitory factors in white glumes than
red glumes which act independently of the germination
inhibitors in the seed. This conclusion is drawn from the
fact that though significant differences in germination of
threshed seed were noted between seeds deveIOped in red
and white glumes, this difference was not observed in
the unthreshed germination tests of these same lines.
Therefore, one must conclude that the white glumes have
a higher level of inhibitory action to surpress germination
and nullify the difference. Caution should be exercised in
this interpretation since only eight pairs were studied
and study of individual pairs indicate the presence of a
reverse trend in some pairs. Whether the influence of
these latent factors on germination of the seed is direct
or indirect will require further investigation. Ching
and Foote (l96l) and George (I967) reported that post-harvest
dormancy of threshed seeds of wheat could be broken if the
seeds were subjected to low germination temperature. The
results obtained from the threshed seed tests in this study

compare favorably with these results. However, in the

27

unthreshed seed tests the treatment for terminating seed
dormancy seemed to be ineffective. Further tests showed
that a low germination temperature broke the dormancy in
seeds enclosed in white glumes in the unthreshed seed
tests. The condition of post-harvest dormancy could not
be broken in this manner in the seeds enclosed in red
glumes in the unthreshed seed tests.

From these observations one could state that post-
harvest dormancy in unthreshed seed of wheat could be over-
come by low germination temperature if the glumes are white
but not where the glumes are red. Probably, a low germination
temperature could block in some way the inhibiting charac-
teristics of the latent factors both in white glume and red
seed and promotes seed germination. However, in the case of
red glume, it could be assumed that under low germination
temperature new cellular components are synthesized which
prevent seed germination directly or indirectly. The
conclusions in this experiment were draw from selected

material and could not be applied to wheat in general.

REFERENCES CITED

Belderok, B. l96l Studies on dormancy in wheat. Pro. Inter.
Seed Testing Assoc. 26:697-760.

I965 Influence of pre-harvest weather on

 

wheat dormancy and its tendency to Sprout in the ear.
Zeitschrift fur Acker-und Pflanzenbau, Band I22, Heft 4,
Seiten 297-3I3 (Eng. summary).

Ching, T. M., and W. H. Foote l96l Post-harvest dormancy
in wheat varieties. Agron. J. 53:l83-l86.

Cox, L. G., H. M. Munger, and E. A. Smith I945 A germination
inhibitor in the seedcoat of certain varieties of cabbage.
Plant Physio. 20:289-294.

Crocker, W. l9l6 Mechanics of dormancy in seeds. Am. J.
Bot. 3:99-I20.

Elliott, B. B., and A. C. Leopold I953 An inhibitor of
germination and amylase activity in oat seed. Physio.
Plant. 6:65-77.

Everson, E. H., and R. 5. Hart l96l Varietal variation for
dormancy in mature wheat. Mich. Ag. Exp. Ana. Bul.
43:820-829.

George, D. W. I967 High temperature seed dormancy in wheat

(Triticum aestivum) Crop Sci. 7:294-253.

28

29

Greer, E. N., and J. B. Hutchinson I945 Dormancy in
British-grown wheat. Nature l55:38l-382.

Harrington, J. 8. I932 The comparative resistance of wheat
varieties to sprouting in the stook and windrow.

SCI. Ag. I2:636-645.

Harrington, J. B., and P. F. Knowles I940 The breeding
significance of after-harvest sprouting in wheat.
Sci. Ag. 20:402.

Hutchinson, J. 8., E. N. Greer, and C. C. Brett I948
Resistance of wheat to sprouting in the ear. Preliminary
investigation. Exp. J. Exp. Ag. l6:23-32.

Keyser, A., and B. Boyack l9l8 Mendelian inheritance in
wheat and barley crosses. Agri. Exp. Sta. of Colorado
Agric. College Bul. 299.

Link, K. P., and J. C. Walker I933 The isolation of
catechal from pigmented onion scales and its significance
in relation to disease resistance in onion. J. Biol.
Chem. l00:379-383.

Lomejko, 5. I937 Maturation of winter wheat grain after
the harvest. Arhiv. Ministartua Poljoprivcede

(Boagrad) 4:88-l08. (Translated).

30

Miyamoto, T., and E. H. Everson I958 Biochemical and
physiological studies of wheat seed pigmentation.
Agron. J. 50:733-734.

Miyamoto, T., N. E. Talbert, and E. H. Everson l96l
Germination inhibitors related to dormancy in wheat
seed. Plant Physio. 36:739-746.

Mosheov, G. I938 The influence of the water extract of
wheat seeds upon their germination and growth. Pales.

J. Bot. l:86-92.

Muller, H. W. I964 About breeding of sprouting resistant
cereals. Plant Breeding Abs. Vol. 34, No. 2, pg. I89,
No. l542.

Nagao, S., E. Takahashi, and T. Miyamoto I957 Biochemical
studies on red rice pigmentation. Japan. J. Genet.
32:l24-l28.

Percival, J. l92l The wheat plant. A monograph. E. P.
Dutton and Company, New York. pp. l02—l03 and 369.
Peterson, R. F. I965 Wheat. World CrOp Books. Interscience

Publisher Inc., New York. pp. 40-4I and 75-76.
Smith, L. I948 The effect of chaff of cereals on germination

of seeds and on growth of mold. Agron. J. 40:32-33.

3l

Wellington, P. S. l956a. Studies on the germination of
cereals. I. The germination of wheat grains in the
ear during development, ripening and after ripening.
Ann. Bot., N. S. 20:l05-l20.

l956b. Studies on the germination of

 

cereals II. Factors determining the germination
behaviour of wheat grains during maturation. Ann. Bot.,
N.S. 20:48l-500.

Wellington, P. S., and V. M. Durham I958 Varietal
differences in the tendency of wheat to sprout in the

ear. Emp. J. Exp. Ag. 26:47-54.

APPENDIX A

33

Table a. Analysis of Variance of the Threshed Seed Germination
Data in Table 3. Glumes not present during
germination .

 

 

Source of d.f. S.S. M.S. , E.M.S. F Test
Variation .
Replication l 94.6l3 94.6l3
Temperature I l369.5l3 l369.5l2 .Ogi808a1l600T **
Error a I 6.049 6.049 0§+800§
. 0.2 0,2 2
Pair 7 8I2.900 ll6.l29 5+5 b+4opb **
2 2
T. x P. 7 7l8.337 l02.620 O§+50b+200TP **
2
Glume color I 1 72.200 72.200 0§+506+I6000c **
T. x Gc. l 59.5I2 59.5l2 O§+50648OOTGC **
2.
P. x Gc. 7 2II.550 30.22l 0§+506+200PGC **
2
T. x P. x Gc. 7 l72.738 24.677 O§+506+IOOTPGC **
Error b 30 7l.538 2.385 Oé+506
Sampling Error 256 565.000 2.207 0%
Total 3l9 4l53.950

 

”**” means significant at .0I level of significance

+ Seed in test produced in heads with either red or white glume

34

Table b. Examination of the Temperature x Pair Interaction
(T.xP.) for the Data of Table 3.

 

 

 

Pair Eggperatggg. t] - t2+' F-test _
p] I.90 l.65 0.25 n.s.+*
P2 5.30 l.65 3.65 **

P3 5.30 I.50 3,80 **

p4 l.80 l.50 0.30 n.s.

p5 3.75 1.65 2.10 **

P6 9.40 l.7O 7.70 **

p7 9.20 l.80 7.40 **

P8 9.80 I.90 7.90 **

 

+ t: and t2 stand for 20C. and IOC., reSpectively

++ ”n.5,” means nonsignificant at .05 level 0f significance
** means significant at .0I level of significance

35

Table c. Examination of the Temperature x Glume Color
Interaction (T.x Gc.) of the Data of Table 3.
Glumes not present during germination

 

 

Temperature
Glume 20C. . IOC. t] - t2 F-test
white 4.900 l.625 3.275 **

red 6.7l3 l.725 4.988 **

 

Table

36

d. Examination of the Pair x Glume Color Interaction

(P.ch.) for the Data of Table 3.
present during germination

Glumes not

 

 

 

Pair Glume W - F-test
White Red

p] l.55 2.00 - 0.45 n.s.
p2 2.05 4.09 - 2.04 .**

p3 2.25 4.55 - 2.30 **

p4 l.85 l.45 0.40 n.s
p5 3.85 2.05 l.80 *'

p6 4.50 6.60 - 2.I0 **

p7 4.l5 6.85 - 2.70 **

P8 6.40 5.30 1.10 **

 

+‘ W and R stand for white and

II)?”

means significant at .05

red glumes

level of significance

37

Table e. Examination of the Pair x Glume color Interaction
(P.ch.) for IOC. for the Data of Table 3.
Glumes not present during germination

 

 

 

 

IO C.
Pair Glume—7 W - R F-test
White Red
p] l.6 I.7 - I n.s
p2 l.5 l.8 — .3 n.s
p3 l.5 l.5 .O n 5
p4 l.5 l.5 .0 n.s
p5 I.7 l.6 l n 5
p6 l.6 l.8 - .2 n.s
p7 l.6 2.0 ‘ .4 n 5
p8 2.0 1.8 .2 n.s

 

38

 

 

 

 

Table f. Examination of the Pair x Glume Color
Interaction (P. x Gc.) for 20 C. for the
Data of Table 3. Glumes not present
during germination
420 C.
Pair Glume W - R F-test
White Red
p] l.5 2.3 _ .8 n.s
p2 2.6 8.0 -5.LI **
p3 3.0 7.6 -4.6 **
p4 2.2 l.4 .8 n 5
P5 5.0 2.5 2.5 **
p6 7.4 Il.4 -4.0 **
p7 6.7 ll.7 -5.0 **
p8 l0.8 8.8 2.0 **

 

APPENDIX B

Table 2.

40

germination data in Table 4.
during germination

Analysis of Variance of the unthreshed seed
Glumes present

 

 

Source of d.f. S.S. M.S. E.M.S. F-test
Variation

Replication l 7372.800 7372.800

Temperature I 500.000 500.000 MOé+800§+I6DDT n.s
Error a l 2l5.5l2 2l5.5l2 O%+800%

Pair 7 5324.537 760.648 0%t50614ODF **
T. x P. 7 4806.350 686.62l U%+506+200TP **
Glume color I l8.050 l8.050 08+508+l6008c n.s.
T. x Gc. 1 484.762 484.762 0515061800TGC ..
P. x Gc. 7 I762.000 25l.7l4 Og+506+208PGc n.s
T. x P. x Gc. 7 26l7.088 373.870 O%+506+IOOTPGC n.s.
Error b 30 5l85.288 l72.843 0%I506

Sampling Error 256 4648.000 18.156 0%

Total 3l9 32934.387

 

4l

Table b. Examination of the Temperature x Pair Interaction
(T. x P.) of the Data of Table 4

 

 

 

Pair 2figamperaturcleaé. t] - t2 F-test
p] 7.050 8.533 — l.483 n.s.
p2 13.866 8.350 5.5l6 **
p3 I0.5l6 8.250 2.266 n.s.
P4 6.483 8.550 - 2.067 n.s.
p5 7.ll6 8.3l6 - I.200 n.s.
p6 l2.650 9.583 3.067 *
p7 8.833 l0.300 - l.467 n.s.
p8 10.700 8.700 2.000 n.s.

 

42

Table c. Examination of the Temperature x Glume
Color Interaction (T. x Go.) of the Data
of Table 4. Glumes present during
germination.

 

 

 

Temperature

Glume t] - t2 F-test
20C. IOC.

white l0.l4l 8.487 l.654 *

red 9.l62 9.l50 0.0l2 n.s.

 

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