GENETIC ANALYSIS OF YIELD AND YIELD RELATED TRAITS IN SUNFLOWER (Helianthus annuus L.) UNDER WELL-WATERED AND WATER-STRESSED CONDITIONS

Drought stress is one of the factors which influence sunflower (Helianthus annuus L.) production. Breeding for tolerance to drought stress has become a major focus. In the present investigation, combining ability, gene action and genetic analysis of several characteristics were studied in six pure lines of sunflower and their 15 hybrids. The materials were evaluated in two separate experiments using a randomized complete block design (RCBD) with three replications in two states (well-watered and water-stressed) under controlled conditions. Comparison of mean values exhibited that under water-stressed condition the average performance of sunflower genotypes were decreased for all studied traits. In well-watered condition the highest value for seed yield per plant (SY) was observed in the cross 'LR4xLR25', whereas in water-stressed condition the highest value for this trait was observed in the hybrid 'C104xLR25'. Combining ability analysis revealed that most of agronomical traits such as head diameter, number of achene per head, head weight and seed yield inherited differently in stressed and non-stressed conditions. In water-stressed conditions, the non-additive effects played a more important role for controlling the number of achene per head (NA), seed yield per plant (SY), head diameter (HD), and days from flowering to physiological maturity (DFM) than additive. Based on results yield improvement for water-stressed conditions requires selection under drought conditions. In well-watered condition, the cross 'LR4xC10' showed the best SCA value for seed yield per plant (SY). In water-stressed conditions, 'RHA266xC100' had the highest SCA for seed yield per plant (SY) and number of achene (NA) per head.