MORPHO-PHYSIOLOGICAL AND MOLECULAR DIVERGENCE STUDY FOR TERMINAL HEAT STRESS IN BREAD WHEAT (Triticumaestivum L.)
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Date
2021
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DRPCAU, PUSA
Abstract
A research was performed out at the Wheat Breeding Section, DRPCAU, Pusa, Samastipur, Bihar during rabi 2020-21, to assess the genotypes of bread wheat (Triticumaestivum L.) for terminal heat stress under late sown conditions. Variability, genetic progress, correlation, path analysis,molecular characterization and diversity analysis were all investigated. 29 genotypes were cultivated in non-stressed (timely sown) and stressed conditions (late sown). Three replications of the experiment were set up in each environment using Randomized Block Design.
Analysis of variance under both timely and late sown circumstances showed considerable variations amongst the genotypes for almost all the traits under study.The characters like Tillers per plant (TPP), Grains per spike (GPS), Grain yield per plant (GYP) exhibited high heritability coupled with high Genetic advance as percent of mean. GYP exhibited significant positive association, with TPP, GPS, Chlorophyll content (CC) and Thousand grain weight (TGW). However, it was negatively associated with Canopy temperature (CT) and Heat susceptibility index (HIS) under both conditions. GYP showed non-significant negative correlation with Days to fifty per cent flowering (DFF) under stress condition. CT revealed negative association with GYP, GPS, CHL and HI. However, it showed significant positive correlation with HSI. It indicated that elevated CT accompanied yield reduction under heat stress condition. The traits viz., TPP, HI and GPS have to be given
importance in selection process for improvement in yield, since they had positive correlation with grain yield. GPS and HI had high direct effect towards grain yield and also all other characters contributed indirectly towards grain yield via these characters.
29 genotypes were grouped into nine and six clusters in timely and late sown conditions respectively. Under timely sown condition Maximum inter cluster distance was reported between cluster VIII and VI, followed by cluster VIII and III, cluster VIII. Whereas under late sown condition, Cluster VI and III reported maximum inter cluster distance, followed by cluster V and III, cluster IV and III.
GYP devoted highest percentage towards the overall divergence followed by DFF, DM and TPP under timely sown condition. Maximum contribution towards the overall divergence was reported by GYP followed by CHL, DFF and TGW. This suggests that selecting genotypes for these characters might be beneficial for further use in breeding programmes in the corresponding environments. Genotype RAUW401 can be selected as suitable donor parent for characters like GPS, TGW and SL under timely sown conditions. RAUW419 can be used in breeding programmes for traits like SL, CHL, TGW, HI and least HSI in late sown conditions.
A set of eleven Simple Sequence repeat (SSR) markers were used for estimation of molecular diversity in the present material. These markers produced distinct and sharp scorable bands for all the genotypes. On the basis of molecular diversity all 29 genotypes have been categorized into 4 groups. Maximum genotypes were accommodated in group I and minimum in group II. High similarity coefficient was found between RAUW419 and Rajendra Ghehu3 followed by RAUW402 and RAUW404.