Evaluation of drought tolerance in bread wheat genotypes under dryland and supplemental irrigation conditions

Abstract

Drought is a wide spread problem seriously influencing wheat (Triticum aestivum L.) production, mostly in dryland regions. This study was conducted to determine drought tolerance genotypes with superiority in different stressed environments. Eighteen bread wheat genotypes were tested in a randomized complete block design with four replications in two years (2006- 2007 and 2007-2008). Stress intensity in the first and second year were low (SI=0.336) and high (SI=0.604), respectively. Five drought resistance indices include mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (TOL), susceptible stress index (SSI) and stress tolerance index (STI) were applied on the basis of grain yield in dryland and supplemental irrigation conditions. Based on different drought indices, genotypes G1, G3 and G4 had the best rank with low standard deviation. The results indicated they have stable yield performance. Bi-plot display and cluster analysis cleared superiority of these genotypes in both years. Synthetic-derived materials had 2.6 to 18% higher yield than the best local check cultivars. The synthetic derived cultivars could perform well across all environments with better agronomic performance, especially for thousand kernel weight. Results showed MP, GMP and STI indices were more effective in identifying high yielding cultivars in diverse water scarcity.