Efficiency of screening techniques for evaluating durum wheat genotypes under mild drought conditions

The main objective of this research was to evaluate fifteen durum wheat (Triticum durum) genotypes selected from joint project of Iran/ICARDA for drought tolerance using several indices. The trials were conducted under moderate levels of drought stress for three cropping seasons (2004-2006) in four locations in the highlands western of Iran. The combined ANOVA for grain yield over years and locations indicated significant differences among main effects (genotypes, years, locations) and their interactions. Principal component (PC) analysis based on the Spearman’s rank correlation matrix revealed that the screening methods were significantly inter-correlated with each other and can be classified into three groups; The first group included stress susceptible index (SSI), tolerance index (TOL) and yield stability index (YSI) where had significantly negative correlation with mean grain yield under supplemental irrigation condition and were able to identify drought resistant genotypes with low yielding performance. The second group reflects the drought tolerance indices including stress tolerance index (STI), geometric mean productivity (GMP), mean productivity (MP) and superiority index (Pi) which were appear to identify the high yielding semi-dwarf genotypes (G6, G4 and G3) with high drought tolerance. The parameters of relative adaptability to drought (bN), regression intercept (a) and regression coefficient (b) are in third group which were able to distinguish the genotypes G6, G5 and G10 with high adaptability and relative drought resistant. The final conclusion of this study is to reveal that not only genotypes but also screening methods can be classified into distinct groups considering different concepts of drought tolerance, resistance and susceptibility under mild drought stress.