Evaluation of Agro-Physiological Characteristics and Drought Tolerance in Some of Durum Wheat Breeding Genotypes

In order to study of agronomic, physiological characteristics, drought tolerance and to identify  Agro-physiological traits associated with drought tolerance, 19 durum wheat genotypes consisting of 17 advanced breeding lines and two control cultivars (Saji and Zahab) were evaluated in a randomized complete blocks design with three replicated under both stress (rainfed condition) and non-stress (supplementary irrigation) durum 2017-18 cropping season at Sararood rainfed agricultural research station, Kermanshah, Iran. The genotypes were assessed for grain yield, agro-physiological traits, and some yield-based drought tolerance indices such as stress tolerance index (STI), geometric mean productivity (GMP), mean productivity (MP), tolerance index (TOL), stress susceptible index (SSI) and yield stability index (YSI). Based on the results of ANOVA and mean comparison, significant differences were observed among the genotypes for the statued traits. The genotypes URRACA، BERKMEN//68.111/WARD و ALTAR 84/STINT//… had the highest grain yield under both stress and non-stress conditions. Based on the genotype x trait biplot analyses, the correlations of studied traits with grain yield was not consistent across both water stress conditions, showing the effect of drought stress on grain yield and the contribution of the traits to yield productivity in durum wheat genotypes. Under stress condition the grain yield was positively associated with spike length, the number of grains per spike (NGPS), grain filling period, biological yield (BY), and days to heading, while under non-stress condition the grain yield positively correlated with NGPS, BY and harvest index. Assessment of genotypes based on drought tolerance indices indicated that the STI, GMP, and MP strongly associated with grain yield under both stress and non-stress conditions; thus, selection of genotypes based on these indices will increased grain yield in both conditions. Based on the results, genotype No. 12 (URRACA) with the highest drought tolerance found to be highest yielding genotype in both conditions. This genotype showed 39.8% superiority than the best control (Zahab cultivar) under rainfed condition; and showed 15% superiority under supplemental irrigation condition than the best check (Saji cultivar). This genotype was characterized as genotypes with high grain yield, moderate in earliness, high grain filling period, lower stomatal conductance and canopy temperature, and high values of chlorophyll fluorescence, spike length, and biological yield. These agronomic and physiological characteristics increased drought tolerance in this genotype, which may be explored in the durum wheat breeding program.