LINE X TESTER ANALYSIS ACROSS YEARS TO STUDY COMBINING ABILITY IN FORAGE SORGHUM (Sorghum bicolor L. MOENCH )

The aim of this study is to determine the magnitude of GCA and SCA effects as well as the genetic parameters involved in forage yield and its component in sorghum. This study was carried out at the Sakha Agriculture Research Station during 2007, 2008 and 2009 summer seasons. Two male and four females were crossed according to line x tester mating design in 2007 growing season to assess combining ability
and nature of gene action. The results of variance over the two years revealed that highly significant differences among tested crosses for all the studied traits. This results indicating the existence of wide variability among the genotypes. The general combining ability effects cleared that positive values were observed for both male
and female for most of studied traits indicating to this genotypes is a good combiner for inheritance of this traits. The results for contribution of lines , testers and line x tester cleared that the contribution   of testers were greater than lines and line x
tester for all the studied traits with except green leaf / stem ratio and dry leaf / stem ratio at the three cuts. Also, the results indicated that the additive genetic variance (δ²A)  were larger than the corresponding values non additive genetic variance including dominance (δ²D )   for most of studied traits. These results suggested that the additive genetic variance played the major role in the genetic expression for all traits with few exceptions. However, heritability in broad sense (h² b.s %) was larger than heritability in narrow sense (h² n.s %) for all the studied traits indicating also to the role of non- additive genetic variance in the expression of these traits. Therefore, from the previews results it could be suggesting the recurrent selection program is important for improving these traits.