Heritability and Genetic Parameters of Some Antioxidant Enzyme Activities in Barley (Hordeum vulgare L.) Cultivars under Salinity Stress

In order to study the heritability and genetic parameters of antioxidant activity in barely (Hordeum vulgare L.) under salinity stress, a seven-parent half diallel (F-1 crosses + parents) was conducted in the non-stress and salt stress (8 and 12 dS m(-1)) conditions in the greenhouse, during 2016-17, Ardabil, Iran. In this experiment, antioxidant enzymes ascorbate peroxidase (APX), catalase (CAT) and superoxide dismutase (SOD) were measured. The results showed that the salinity had increased the expression of all of the three enzymes and the activity of enzymes were differed under different salinity levels. The average degree of dominance was higher than unity for all cases, suggesting the control of traits by overdominance. Under saline condition heritability in narrow sense (h(2)n) was found low to medium (0.11-0.41) but their broad-sense heritability (h(2)b) was estimated relatively high (0.74-0.90). The results suggested the lack of heterosis in control of these traits except for APX activity in 8 dS m(-1) salinity. Results showed that in APX activity recessive alleles were favorable, in CAT activity, under non-stress condition, dominant alleles, and under 12 dS m(-1) salinity, recessive alleles were desirable; although, such relations were not clearly revealed in SOD activity. Due to the importance of dominance, it was indicated that the evaluation of genotypes must be done at progressive breeding program. Based on general combining ability effects, it was concluded that under salinity, Rihane and Nosrat had favorable alleles for APX activity. In CAT activity, Nosrat had favorable alleles. In case of SOD, Afzal and Valfajr had favourable alleles. In spite of the importance of physiological traits as selection criteria in breeding of salinity tolerance, presence of large dominance effects should not be neglected and selection for these traits should be delayed until after some inbreeding.