Evaluation of general and specific combining ability of new sunflower inbred lines

In this study general and specific combining ability of new sunflower inbred lines accompanied by components of genetic variance were estimated using Line x Tester method. Six restorers obtained from exotic hybrids were crossed with four CMS lines as tester in 2005. 24 combinations with check cultivars Alstar and Azargol were planted in randomized block design with four replication in Khoy agricultural and natural resources research station in 2006. After Analysis of variance for agronomic traits, components of genetic variance and general and specific combining abilities were estimated. The results showed that there is variability between hybrids and testers considering all traits except head diameter. All traits except head diameter and plant height were under control of both additive and dominant effects. Seed yield mainly was under control of dominant effects. For Growth period the dominant effects were important than additives and in other traits additive effects had major impression. Over dominant effects for growth period and seed yield, complete dominant for plant height and partial dominant for other traits were obvious. Restores RG85-50, RG85-21 and RG85-23 and Testers AG85-52 and AG85-148 had the highest GCA for seed yield but only AG85-52 had significant GCA in desired (+) direction. RG85-26 and RG-85-50 for growth period and RG85-19, RG85-26, RG85- 23 and RG85-21 considering flower initiation, plant height , 1000 seed weight and head seed number respectively had significant GCA in desired (+/-) direction. Single branch restorer RG-85-50 was distinguished as a good line for using in crossing programs because of having desired GCA for seed yield and growth period. Combinations RG85-23 x AG85-78 and RG85-56 x AG85-356 had the best SCA for seed yield and growth period.This two hybrids had seed yield of 4105 and 3022 kg/hac respectively and growth period of 107 days. RG85-21 x AG85-52, RG85-23 x AG85-7, RG85-21x AG85-148, RG85-50 x AG85-52, RG85-26x AG85-52 , RG85- 19 x AG85-148, RG85-26 x AG85-148 because of having high yield potential will be evaluated in later experiments. Combinations of RG85-21, RG85-26, and RG85-50 with AG85-52 and RG85-21 x AG85-148 because of their higher seed yield (over 3500 kg/hac) and 107 days growth period are valuable early mature hybrids in summer cropping.