Evaluation of General and Specific Combining Ability of Some Sunflower Inbred Lines under Normal and Drought Stress Condition

Sunflower is a semi-drought tolerant plant that due to its importance in oil production, the area under cultivation is expanding. But drought stress severely reduces the yield of grain and oil. Therefore, the production and introduction of hybrid cultivars can help increase performance. The first step in the production of hybrid is to identify parents based on their General and Specific combining ability and also to determine the type gene actions.

In order to investigate the combining ability of sunflowers inbred lines under normal conditions and drought stress, a study using 12 sunflower hybrids obtained from the cross of male sterile and tester lines with two controls, Qasem and Shams, in two separate experiments in the form of The design of randomized complete blocks with three replications was performed under two conditions of normal irrigation and drought stress.

The results of combined analysis of variance of the studied treatments under both normal and drought stress conditions showed that drought stress had a significant effect on all studied traits number of seeds per head. The effect of lines for plant height, oil percentage and head diameter and the effect of testers were significant for most traits except number of seeds per head, which shows a significant difference between the general combinability of lines and testers. Also, line 1 and tester 3 in both normal and stress conditions with a negative and significant combinability for the height of the parent plant is suitable to reduce this trait in the cross. In addition, line × tester interaction had a significant effect on most traits except 1000-seed weight and number of seeds. The Line 1 and Tester 1 with significant positive general combining ability (GCA) effects for grain yields were considered as suitable combiners for improving these traits. So that under normal conditions, hybrid No. 13 with grain yield of 5224 kg / ha had the highest grain yield and under stress conditions of hybrid No. 31 with an average of 3544.6 kg / ha had the highest grain yield.

The general results of this study show that the important traits of grain yield, oil percentage and oil yield are controlled by the dominance gene action, which can be improved by hybridization and best selection of parents in breeding programs.