Assessment of wheat genotypes for yield potential and stress adaptation

Abstract

Post-anthesis drought stress is the most important factor affecting wheat
production adversely in dry-land area. In order to evaluate drought
tolerance in bread wheat varieties, an experiment was conducted
with 125 promising genotypes in randomized block design with two
replications each in no-stress and stress environments. Post-anthesis
stress was created after 14 days after anthesis. Different drought
tolerance indices viz., stress susceptibility index, relative drought
index, mean productivity, stress tolerance index, geometric mean
productivity, yield index, yield stability index, drought resistance
index were evaluated based on grain yield under stress and non-stress
conditions. Thirty-one varieties recorded significantly higher grain
yield under stress environments along with significant favourable
most of the drought indices viz., SSI, RDI, MP, STI, YI, YSI and DRI.
Only 2 genotypes, 31ESWYT-147 and C-306 produced significantly
high grain yield in both stress and non-stress conditions. Further,
31ESWYT-147 also showed significant favourable values of all drought
tolerance indices except GMP, whereas, C-306 showed significant
favorable values only for MP, STI, YI and DRI, respectively. STI and
MP showed mostly positive and meaningful genotypic and phenotypic
correlation with yield in both stress and non-stress environments
and with other drought tolerance indices. Thus application of both
indices could be appropriate while screening the varieties for drought
tolerance. However, according to both STI and MP indices, promising
genotypes varied differentially for drought tolerance. MP index leads
the selection towards more efficient genotypes in both stress and nonstress
environment. Thus screening for drought tolerances could be
made either one or both of these two indices would be more effective
in bread wheat. Drought indices had low heritability and genetic
gain which were comparable to yield in stress but higher than yield
in non-stress condition. Hence the improvement for yield potential
under drought could be achieved through direct selection in stress or
screening through STI and MP indices.