Genetic Analysis for Heat Tolerance in Wheat (Triticum aestivum L.)
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Date
2022-09-19
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Agriculture University, Jodhpur
Abstract
An experiment entitled “Genetic Analysis for Heat Tolerance in Wheat
(Triticum aestivum L.)” was carried out at Instructional Farm, College of
Agriculture, Jodhpur (Rajathan) during Rabi season of 2021-22. The experiment was
laid out in Randomized Block Design (RBD) with forty genotypes and three
replications in three environmental conditions and observations of days to heading,
days to maturity, plant height, number of tillers per plant, peduncle length, flag leaf
area, spike length, grain yield per plant, harvest index, 1000-grain weight, canopy
temperature, membrane stability index, chlorophyll content and heat tolerance index
(HTI) were recorded.
Analysis of variance depicted significant difference for all the traits under
study, indicating that good amount of inherent variations were present. The
phenotypic coefficient of variation (PCV) was higher than genotypic coefficient of
variation (GCV) for all the traits under study, indicating influence of environment on
expression of such traits. The highest value of PCV and GCV were observed for
canopy temperature and the lowest for days to maturity in all three environments.
Traits showing high heritability in D1 were chlorophyll content, canopy
temperature, grain yield per plant, flag leaf area, 1000-grain weight, number of tillers
per plant, peduncle length and days to heading while, in D2 number of tillers per
plant, 1000-grain weight, flag leaf area, chlorophyll content, plant height, grain yield
per plant, canopy temperature and spike length. In D3 environment, 1000-grain
weight, harvest index, chlorophyll content, grain yield per plant, flag leaf area,
peduncle length and plant height. High heritability coupled with high genetic advance
as per cent of mean was observed for chlorophyll content, canopy temperature, grain
yield per plant and number of tillers per plant in D1 while, in D2 it is recorded for
traits like chlorophyll content, canopy temperature, grain yield per plant, number of
tillers per plant, 1000-grain weight and flag leaf area. In D3 for grain yield per plant,
1000-grain weight, flag leaf area, peduncle length, harvest index and plant height,
indicating that these traits were governed by additive gene action. Hence, for the
improvement in grain yield, selection on these traits could be made.
Analysis of correlation coefficient revealed that grain yield per plant had
positive and significant correlation with harvest index and 1000-grain weight in D1
and D3 environment while, in D2 plant height, peduncle length and spike length
exhibited positive and significant correlation with grain yield per plant. These results
illustrate that these traits are important in contribution to grain yield.
Path coefficient analysis revealed that the highest positive direct effect on
seed yield per plant exhibited by membrane stability index followed by peduncle
length, harvest index and flag leaf area in D1 environment. In D2 environment,
harvest index, canopy temperature, peduncle length, days to maturity, spike length
and membrane stability index while, in D3 environment harvest index and peduncle
length.
High variations were observed for heat tolerant index (HTI) in this study.
HTI values ranged between 0.293 to 1.196 in D2 and 0.120 to 0.429 in D3. The
genotypes with high HTI value were considered as heat tolerant or resistant,
meanwhile, genotypes with low HTI value were considered as heat susceptible. In D2
genotype TAW-221 was best among the heat tolerant and can be used as heat tolerant
or resistant genotype.
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Citation
Badgotya, Pinky 2022. Genetic Analysis for Heat Tolerance in Wheat (Triticum aestivum L.). M.Sc. Thesis, Agriculture University, Jodhpur