Combining ability of some sunflower parental lines in both normal and drought stress conditions

Abstract General and specific combining abilities of three cytoplasmic male sterile and four restorer lines of sunflower were studied in a randomized complete block design with three replications under normal irrigation and drought stress conditions in Eslamabad-e-Gharb, Iran during two growing season (2019 and 2020). Drought stress reduced seed yield, oil yield, thousand seeds weight and head diameter by 21.9%, 18.1%, 14.3% and 11.5%, respectively. Line × tester analysis indicated that the effect of lines was significant for the number of days to flowering, plant height, grain yield and seed oil percentage under both normal and drought stress conditions. The effect of lines was significant for number of days to maturity and number of seeds per head under normal condition and for thousand seeds weight under drought stress condition. Contribution of lines × testers were higher than the variances of lines or testers for of most of all the studied traits indicating the major role of non-additive effects on expression of theses traits. R131 was differentiated with the highest positive general combining ability for grain and oil yield in both normal and drought stress conditions. Among the testers, AGK32 and AF81-222 had the highest general combining ability for grain yield under normal and stressed conditions, respectively. R131×AGK38, with grain yields of 4414 and 3457 kg ha-1 under normal and drought stress conditions respectively, had the highest specific combining ability for grain and oil yield under both conditions. The results of this study showed that the genetic materials and environmental conditions can affect the nature of gene effect and combining ability of sunflower parent lines and crosses.