Selecting tolerant barley genotypes to terminal drought stress based on grain yield stability and stress tolerance indices

To overcome the increasing requirement of agricultural production in the future climate scenarios, the most effective and economic approach is to breed cultivars with high drought tolerance. To select drought tolerant lines in barley, 19 promising barley lines along with a check variety, Goharan, were evaluated under two environmental conditions, normal and terminal drought stress. The experiment was conducted in a randomized complete block design with three replications at the South Khorasan Agricultural and Natural Resources Research and Education Centre, during two cropping years, 2019-2021. Comparison of the environmental means showed that days to maturity, grain filling period, 1000-grain weight and grain yield of the studied lines in the first year were significantly reduced by drought stress. The results of the drought sensitivity and tolerane indices indicated that YI, HM, STI and GMP indices can be used to select barley cultivars and lines in the areas that are exposed to terminal drought stress, but in other areas, MP, STI, GMP and HM indices are suggested. Based on this result, lines number 20, 11 and 14 were respectively determined as the most tolerant lines to terminal drought stress in this experiment. Evaluation of stability indices and estimation of their correlation with grain yield of the studied lines also showed that grain yield had a positive and significant correlation with the variance of genotype and environment interaction (θ₍ᵢ₎) and regression coefficient (b) and a negative and significant correlation with the Kang (KR) and Thennarasu (NP(2,3)) statistics. In total, the results of most stability statistics investigated in this experiment showed that lines number 20, 14 and 8 were high-yielding and stable lines for cultivation under both normal and terminal drought stress conditions.