Evaluation of Drought Stress Tolerance in Some Faba Bean Genotypes Using Drought Tolerance Indices and Biochemical Compounds

To evaluate drought tolerance in faba bean genotypes, 21 genotypes were studied in a randomized complete block design with three replications under normal irrigation and drought stress conditions. The experiment was conducted in 2017-2018 at research station of Gorgan, Iran. Indices such as stress tolerance index (STI), stress susceptibility index (SSI), tolerance (TOL), mean productivity (MP), geometric mean productivity (GMP), yield index (YI) and yield sustainability index (YSI) were calculated for all genotypes according to grain yield in normal irrigation and stress conditions. Based on analysis of variance results, there was a significant difference among the genotypes in terms of grain yield in both environments (normal irrigation and drought stress). The results of correlation showed that STI, MP, GMP and TOL are suitable for selection of high-yielding genotypes in both environments, among which STI and MP were the most suitable indices to select drought-tolerant genotypes. Based on STI, MP and GMP indices, GF-65 genotype was classified drought-tolerant, and GF-525 and GF-21 were susceptible according to TOL and SSI indices. Results of cluster analysis showed that GF-66, GF-62, GF-75 and GF-67 were superior compared to other genotypes based on YSI, YI, GMP, MP and STI indices, and utilization of these genotypes may be recommended to achieve high yields in drought stress conditions.