Tolerance and stability studies on durum wheat under drought and heat stress conditions

Abstract

This study was conducted to determine the stability of grain yield and test weight, and the susceptibility index (S) of durum wheat under stress conditions. The genotypes were grown in replicated trials at Ceylanpinar State Farm in Southeast Anatolia under supplementery irrigation between 1992 and 1994, and in lowland and upland conditions in the Mediterranean region of Adana under rainfed conditions between 1992 and 1995. Stability parameters were estimated from the regression analysis as linear regression coefficient (bi) and coefficient of determination (r2), and from Kang’s yield stability index (Ysi). Stress tolerances were estimated using stress susceptibility index (S). Genotypes evaluated in this study exhibited a wide range of stress tolerance and adaptation to stressful environments. Considerable variation in the S values of certain genotypes occurred between stress environments in this research. Stress susceptibility index (S) ranged from 0.835 to 1.243, and from 0.588 to 1.513 for grain yield and test weight, respectively. Test weight index showed greater variation than grain yield index. Differential variation among genotypes for S probably depends on heat stress and drought stress which occurred during grain filling periods. Regression coefficients ranged from 0.674 to 1.306 and from 0.574 to 1.424 for grain yield and test weight, respectively. Kang’s yield stability statistic index ranged from -4 to +27 and from -6 to +28 for grain yield and test weight, respectively. Stable lines, stress-tolerant and susceptible lines were identified for use in the evaluation of stress tolerance screening techniques and of stability parameters. Based on these findings, selected lines have been chosen as valuable initial material in durum wheat breeding for stress environments.