Combining ability and heterosis for yield and yield components in sunflower

Field experiments were carried out during 2005 2007 in order to study the genetic structure of a hybrid sunflower population to identify the parents and crosses showing superior general and specific combining ability and finally to evaluate Gamma(1) hybrid vigour Six artificial hybrids were created using 3 CMS and 2 restorer lines in sunflower (Helianthus annus L) According to the results the ratios of GCA SCA variance were lower than 1 for plant height and head diameter in the both years for number of seeds per head and 1000 seed weight in 2007 and for seed yield in 2006 For all these characters non additive effects were more effective than the other types of polygenetic effects The additive gene actions were significant for 1000 seed weight and number of seeds per head in 2006 and for plant height and seed yield m 2007 since the ratios of GCA SCA variances for these characters were greater than 1 The parental lines CMS 10 and RHA 10 proved to be good combiners having the highest positive GCA effect in yield and certain yield components The crosses CMS 10 x REM 03 CMS 01 x RHA 10 CMS 10 x RHA 10 and CMS 23 x RHA 10 might be considered as promising hybrid combinations in terms of seed yield The values of heterosis and heterobeltiosis values ranged from 109 8 to 218 3% for seed yield All of the tested hybrids showed positive and significant heterobeltiosis for seed yield