HETEROSIS AND COMBINING ABILITY STUDIES OF RATOONING IN RICE (Oryza sativa L.)
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Date
2018
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Acharya N.G. Ranga Agricultural University
Abstract
The present investigation was carried out at APRRI and RARS, Maruteru with
the prime objective of testing eight selected parents, based on the ratoonability
performance in rabi, 2014-15, to elicit information for their combining ability and to
know the gene actions involved in the inheritance of different traits related to
ratoonability in rice. Apart from combining ability studies other parameters like mean,
variability, heritability, expected genetic advance, heterosis, character association and
path coefficient analysis were also studied for twenty four characters (yield attributing
and quality traits) of both F1 main crop and it's ratoon crop during rabi, 2015-16 and
summer, 2016 respectively. Further, in ratoon crop along with number of tillers per
plant, number of ear bearing tillers per plant, additionally another 3 characters viz.,
number of ratoon tillers as percentage of main crop tiller, number of vegetative buds
after the harvest of main crop, number of ratoon ear bearing tillers as percentage of
main crop ear bearing tillers are considered as traits related to ratoonability.
Analysis of variance studies in both main crop and ratoon crop revealed high
degree of variability in the material. The genotypic coefficients of variation for all the
characters studied were lesser than the phenotypic coefficients of variation indicating
the influence of environment on expression of these traits. Wider variability was
observed for gel consistency and alkali spreading value both in F1 and it's ratoon crop
and moderate variability was observed for traits viz., total number of tillers per plant,
number of grains per panicle, LAI at maximum tillering stage, volume expansion ratio,
water uptake, amylose content and grain yield per plant in F1 main crop; and number
ratoon tillers as percentage of main crop tillers, total number of ear bearing tillers per
plant, number of ratoon ear bearing tillers as percentage of ear bearing tillers per plant,
number of grains per panicle, water uptake and amylose content in F1 ratoon crop. High
heritability and high genetic advance as per cent of means were observed for total
number of tillers per plant, number of grains per panicle, leaf area index at maximum
tillering stage, water uptake, gel consistency, alkali spreading value, amylose content
and grain yield per plant both in F1 main crop and it's ratoon crop, revealed the role of
additive gene action. This in turn suggests the feasibility of simple selection procedures
for improving these traits.
Further the analysis of variance for combining ability for both F1 main crop and
it's ratoon crop revealed that parental, crosses and parents vs crosses effects had
significant amount of variability with in each of them for majority of the traits studied.
Out of the eight parents tested for their combining ability the genotype MTU 1001
found to be good combiner in main crop and as well as ratoon crop for the traits, days
to 50% flowering, days to maturity, plant height (cm), test weight (g), leaf area index at
maximum tillering stage, head rice recovery (%), kernel length (mm), kernel linear
elongation ratio, alkali spreading value (mm) and grain yield per plant (g), while the
general combining ability for ratoonability related traits revealed that the parent MTU
1121 and MTU 1061 recorded as a best general combiner for total number of tillers per
plant; MTU 1121, MTU 1140 and MTU 1064 for number of ear bearing tillers per plant
and MTU 1140 for number of ratoon ear bearing tillers as percentage of main crop ear
bearing tillers. Whereas MTU 1001, MTU 1121 and BPT 3291 as good general
combiners for number of vegetative buds and total number of tillers as percentage of
main crop tillers. Therefore these lines can be utilized in improvement of the respective
traits in any breeding programme where hybridization is involved.
Among the 28 cross combinations, the crosses, MTU 1001 × MTU 1061, MTU
1001 × MTU 1140, MCM 100 × MTU 1064 and MCM 100 × MTU 1140 in F1 main
crop; and MTU 1001 × MTU 1140, MCM 100 × MTU 1140 and MTU 1140 × MTU
7029 in F1 ratoon crop expressed high sca effects with high per se performance for
grain yield per plant. These crosses did not express high sca effects for all the yield
attributing traits, revealing that there is no relationship between per se performance of
hybrids and gca effects of parents. The gca effects of parents and sca effects of their
hybrid combinations indicated that the crosses with high sca effects were resulted due
to all possible parental gca combinations i.e., high x high, high x low, low x high and
low x low. Therefore, one can afford to include some low general combiners also along
with good combiners in breeding programmes where hybridization is involved.
Studies on specific combining ability effects for the ratoonability related traits
disclose that, crosses MTU 1001 × MTU 1140, BPT 3291 × MTU 1061 and MCM 100
× MTU 7029 exhibited high sca effects for total number of tillers per plant; and MTU
1140 × MTU 7029, MCM 100 × MTU 7029 and MTU 1001 × MTU 1140 for total
number of tillers as percentage of main crop tillers; the crosses MTU 1001 × MTU
1140, BPT 3291 × MTU 1121 for the trait total number of vegetative buds after the
harvest of main crop; and the trait, total number of ear bearing tillers per plant showed
high sca effects for BPT 3291 × MTU 1061; MTU 1001 × MTU 1140, BPT 3291 ×
MTU 1061. The crosses MTU 1140 × MTU 7029 and MTU 1140 × MTU 7029 showed
high sca for number of ear bearing tillers as percentage of main crop ear bearing tillers.
Gene action studies for the ratoonability related traits revealed the
preponderance of both additive and non-additive gene action in the inheritance of total
number of tillers per plant, total number of ear bearing tillers per plant, number of
ratoon ear bearing tillers as percentage of main crop ear bearing tillers, which can be
exploited by adopting breeding procedures like cyclic hybridization, bi-parental mating
and diallel selective mating systems or by recombination breeding with postponement
of selection at later generations, while the other two traits, number of ratoon tillers as
percentage of main crop tillers and number of vegetative buds after the harvest of F1
main crop) were controlled by non-additive gene action and hence these traits can be
improved either by heterosis breeding and recombination breeding with postponement
of selection at later generations..
Perusal of relative heterosis, heterobeltiosis, sca effects and per se performance,
the cross MTU 1001 × MTU 1140 was identified as a promising hybrid by registering
significant relative heterosis, heterobeltiosis, sca effects and better per se performance
for the traits total number of tillers per plant, leaf area index at maximum tillering
stage, milling per cent, head rice recovery, L/B ratio, gel consistency and grain yield
per plant in F1 main crop; and number of tillers per plant, number of vegetative buds
after the harvest of main crop, number of ear bearing tillers per plant, milling per cent,
head rice recovery, and grain yield in F1 ratoon crop.
Genotypic correlations in general are higher than phenotypic correlations
studies both in F1 main crop and it's ratoon crop indicating that the apparent
associations are largely due to genetic reasons. Considering the nature and magnitude
of character association and their direct and indirect effects, it can be inferred that
improvement of grain yield per plant with good quality trait is possible through
simultaneous manifestation of days to 50% flowering, days to maturity, total number of
tillers per plant, total number of ear bearing tillers per plant, panicle length per plant,
number of grains per panicle, test weight, leaf area index at maximum tillering stage,
milling percentage, head rice recovery, and gel consistency.
Description
D5636
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