The research was carried out at Tal Hedya Research Center in Aleppo, General
Commission for Agriculture Scientific Research (GCSAR), Syria, during 2011
and 2012 seasons. Seven genotypes of cotton were used, and complete diallel
hybridization was m
ade to study general and specific combining ability of some
productivity traits (sympodial branch number, actual boll number and seed cotton
yield). General combining ability (GCA) indicated that the parental genotype
Cherpan432 had a high significant GCA for sympodial branch number and actual
boll number, but the parents Aleppo118 and Deir El-Zour22 had the high GCA for
seed cotton yield. This is a clear indication that these parental genotypes had the
largest number of additive genes action, which plays important role in the inheritance
of the above-mentioned traits. The estimation of SCA values showed favorite and
high significant values in many hybrids resulted from parents, which had highly
significant GCA, which means that the gene action type is (additive x additive), and
this refers that these hybrids possessing the largest number of additive genes. High
heritability broad sense refers to importance of genetic variance in the inheritance of
all characters, but heritability in narrow sense values were low in general, indicating
the importance of dominance and epistasis genes in the inheritance. According to
this result it is recommended to follow the cross method for improvement of the
studied traits.