Seed dormancy in rice: distribution, inheritance and effect on storability of seeds
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Date
2021-12-28
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Department of Seed Science and Technology, OUAT, Bhubaneswar
Abstract
There is need for incorporating seed dormancy and improving storability of seed in rice
crop for which information on the nature of variation and inheritance of these characters would
be useful. The present study was undertaken to analyse the nature of variation of seed
dormancy in different maturity groups (early, medium and late), study the inheritance of the
character and examine the relationship between seed dormancy and storability. The material
consisted of 54 rice varieties for screening in kharif season and later 30 varieties were selected
and evaluated for seed dormancy and storability in kharif and summer seasons. A number of
plants, panicle, seed and biochemical parameters like carbohydrate content, protein content,
dehydrogenase activity and alpha amylase activity were also studied to examine the
relationship of these characters with seed dormancy. Inheritance of seed dormancy was studied
in 6 crosses involving 5 varieties. The efficacy of chemical treatment with maleic hydrazide
(MH) in different concentrations for inducing seed dormancy was also studied to find out the
most effective concentration for inducing dormancy in this crop.
Dormancy periods (DG80) of the varieties ranged from 3 to 13 days in summer and 5 to
39 days in kharif seasons. Dormancy intensity (NGH0) ranged from 4% to 83.67% in summer
and 9.67% to 95% in kharif seasons. These ranges indicated presence of varietal and seasonal
differences for dormancy period and intensity. Most of the early varieties showed minimum
dormancy period and weak intensity while most of the medium to late varieties possessed
maximum dormancy with strong intensity of dormancy. Seeds of kharif season showed the
highest degree of dormancy compared to summer grown seeds. Dormancy period and intensity
showed high positive correlation between them and both showed strong positive association
with days to flowering and maturity. Seed dormancy was found to have a digenic epistatic
control with dormant nature is dominant over non-dormant. There were significant differences
and wide range of variation among the varieties for different measures of storability of seed
indicating presence of varietal differences for this trait. PG80 and PG50 were estimated by probit
analysis which showed that seeds of different varieties in different seasons would maintain
germinability above the minimum certification standard for periods of 8 and 9 months in
summer and kharif seasons, respectively. All measures of storability showed that kharif seeds
stored best than summer seeds. Storability of seed showed strong positive correlation with seed
dormancy. The treatment with 15000 ppm maleic hydrazide (MH) was the most effective
dormancy inducing dosage followed by 10000 ppm and 5000 ppm for rice varieties to prevent
pre-harvest sprouting during monsoon seasons. This same trend was observed in these
treatments for seed vigour parameters.
The study brought out the existence of varietal and seasonal differences for seed
dormancy and storability between and within different maturity groups and a strong positive
relationship between the seed dormancy and storability traits. Several of the late varieties were
found to have maximum seed dormancy, which can be used as such or as donors for transfer of
dormancy to other early varieties to prevent yield losses due to viviparous germination. Seed
dormancy was found to have a digenic epistatic control (complementary and inhibitory gene
action) with dormant nature is dominant over non-dormant, which means that breeding
manipulation of the character would be quite difficult. By incorporating seed dormancy into
early varieties, the storability of the varieties can also be improved. The information obtained
as the most effective dormancy inducing treatment is valuable for avoiding pre-harvest
sprouting (PHS) and useful for preventing yield losses due to PHS during monsoon seasons.