Antioxidant response of sunflower cultivars to drought stress in different stages of grain filling

To evaluate the correlation of physiological traits with yield of sunflower in different stages of grain filling, 9 sunflower varieties were grown in field under terminal drought stress condition. Activity of antioxidant enzymes (APX, CAT and SOD) were measured in 10 day intervals in 3 stages. After maturity grain yield was estimated. In combined ANOVA, significant genotypic differences were observed in grain yield indicating genetic variability of genotypes under study. Our results demonstrated that stress intensity (stage) had a major impact on SOD activity. High Genotype × stress × stage interaction observed in traits indicated that sunflower genotypes respond differently to drought at different stages. Significant correlations were found between grain yield and antioxidant activity (APX and CAT). Genotypes such as Gabor, Armavirsky and Azargol had high grain yield and high antioxidant activity and were selected as superior genotypes.