evaluation of genetic variance components and combining ability in sunflower lines based on line × tester analysis

a study was conducted to investigate the genetic variance components and the combinig ability of sunflowers lines at the seed and plant improvement institute, karaj, iran in 2006. a total of 41 genotypes including 2 cms, 13 restorer and their 26 corresponding hybrids were evaluated in a line × tester approach. the analysis of variance indicated that significant differences existed among genotypes for all of the studied traits except the days from sowing to emergence. the significance of the parents vs crosses variance indicated the presence of heterosis for days to maturity, diameter of head, grain yield and oil yield. the effect of parents was significant for most of the traits except for number of leaves, grain and oil yield. the effect of lines was significant for days to 5%, 50% and 75% flowering, days to maturity, number of leaves, length and width of leaf, plant height and grain yield. the testers effect was significant for plant height, grain yield, 1000 ‎grain weight and oil content. the effect of line × testers was significant only for 1000 ‎grain weight and days to 5% flowering. based on general and specific combining abilities, cms19 (tester) and cmsb × r7 were the best line and hybrid, respectively. the additive genetic effect was important in controling grain yield while dominance gene effect was important in controling 1000 grain weight and oil yield.