Evaluation of Drought Tolerance Indices and Byplot Method in Bitter Vetch Ecotypes

In order to determine the most desirable index of drought tolerance in bitter vetch ecotypes, two separate experiments (non-stress and stress) were conducted in field condition during 2018 using randomized complete block design with four replications. Quantitative drought resistance and susceptibility indices including Stress susceptibility index (SSI), Stress tolerance (TOL), Mean productivity (MP), Geometric mean productivity (GMP), Harmonic mean (HM) and Stress tolerance index (STI) based on grain yield in stress and non stress conditions, were calculated for each ecotypes. Combined analysis of variance over two conditions showed there were significant differences (p < 0.01) among ecotypes for grain yield in stress and non stress conditions. Also, there were significant differences (p < 0.01) between ecotypes for all drought tolerance and resistance indices. MP, GMP, HM and STI were highly correlated (p < 0.01) with grain yield under both stress and non stress conditions. Therefore, they were recommended as the best indices to identify high yielding ecotypes for stress and non stress conditions. Based on these indices two ecotypes Saghazchi and Bayghot were identified as the highest yielding ecotypes under both stress and non stress conditions. Results of three dimensional and byplot graphs recognized the same ecotypes as highest yielding in both conditions, similarly.