Relationships Between Drought Stress Tolerance Indices and Their Use in Wheat Screening Programs

The purpose of this study was to evaluate the indices of drought tolerance and find out the relationships between them and their application in wheat screening programs. In order to proper screening of genotypes, the principal component analysis and biplot were analyzed and genotypes were placed in biplot based on factor scores. An experiment was conducted using alpha lattice design with two replications in rainfed and irrigated conditions using 132 bread wheat genotypes in the Gonbad-e-Kavos Agricultural Research Station in 2015-2016. Based on yield in no stress (YP) and stress (YS) conditions, drought tolerance indices such as stress susceptibility index (SSI), stress tolerance index (STI), tolerance index (TOL), mean production index (MP), Harmonic Index (HM), Yield Index (YI), Sensitivity Drought Index (SDI), Relative Drought Index (RDI), Stress Susceptibility percentage Index (SSPI), Drought Resistance Index (DRI) and yield Stability Index (YSI) Were calculated. Tolerance indices such as STI, GMP, HM, MP and YI had a positive and significant correlation with yield in normal conditions as well as with yield in stress conditions. Therefore, genotypes with large numerical values for these indices had high yield under stress and no stress conditions. TOL, SSPI, DSI and SSI Indices identified genotypes with high yield under normal conditions but sensitive to stress conditions (Group B Fernandez). Also, YSI and RDI indices differentiated genotypes with high yield under stress conditions and low yield under favorable conditions (Group C Fernandez) from other genotypes.