Evaluation of physiological, phonological and morphological traits related to drought tolerance in bread wheat (Triticum aestivum L.)

This research was carried out to identify drought tolerant genotypes on the basis of physiological, phonological and morphological traits and drought tolerance indices in bread wheat. Twenty wheat genotypes were assessed in two field experiments based on randomized complete block design with three replications under non-stress and drought stress conditions in Dryland Agricultural Research Sub-Institute, Sararood, Kermanshah. The studied traits were number of grains per spike, peduncle length, spike length, plant height, 1000-grain weight, days to heading, days to physiological maturity, grain yield, flag leaf area, relative water content, a, b and total chlorophyll, proline content, water retained in cut leaves, cell membrane stability and leaf water potential. Futhermore, drought tolerance indices based on grain yield under stress and non-stress conditions were also evaluated. The results showed that there is significant genetic variation among the studied genotypes for improving drought tolerance. Results of the yield index (YI), yield tolerance index (YTI), mean productivity (MP), geometric mean productivity (GMP), tolerance index (TOL), stability tolerance index (STI) and stress susceptibility index (SSI) identified relatively similar genotypes as the drought tolerant genotypes, but according to the high and significant correlation coefficients among MP, GMP, HMP and STI indices with grain yield under both stress and non-stress conditions, these indices were suitable to identify the high yielding genotypes under both conditions. According to these indices, the genotypes 72YRRGP, T179, T189, 914GB, MARAGHEH(1379-80) and Sardari were detected as the drought tolerant genotypes. Correlation coefficient analysis also revealed that among the evaluated traits, proline content of flag leaf, cell membrane stability and spike length had the stronger relationship with stress tolerance index (STI) and are introduced as the most important traits for selecting drought tolerant genotypes in this research.