Combined selection for productivity and resilience through modified stress tolerance indices in a HUW-234 X HUW-468 derived wheat (Triticum aestivum L.) RIL mapping population for heat stress
Stress indices are a set of quantitative estimators that elucidate stress response by yield data from single or multi-environment evaluations. A major disadvantage of using such indices is the reported lack of correspondence in rankings across indices and their failure to delineate overlapping responses in terms of yields under stress. In the present study, HUW-234 x HUW-468 derived wheat RIL mapping population was used to validate the usefulness of such a modified index. The correlation coefficient between the index score and their original index values were negative for SSI (Stress Susceptibility Index) and TOL (Tolerance Index) and positive for MP (Mean Productivity), GMP (Geometric Mean Productivity) and STI (Stress Tolerance Index). Based on index scores, d two new indices namely YPSI (Yield Production Score Index) and YSSI (Yield Stress Score Index) were created by combining score indices. Using these indices, the RILs could be effectively classified into four stress response classes. Most of the genotypes fall in Class II, III and IV. As such, it is highly imperative to identify highly resilient (Class III) and productive genotypes (Class II) for planned crossing. Based on the results of present and earlier studies, it is proposed that the new indices YPSI and YSSI can be effectively used for evaluating large genotype sets in diverse environments for stress response.
Key words: Wheat, heat stress, RIL population, stress tolerance indices, index scores, YPSI, YSSI
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