الفهرس Only 14 pages are availabe for public view
 |  | from | 156 |  |  |
| | | from | 156 | | |
Abstract
The objectives of this study were to estimate heterosis, combining ability, types of gene action and heritability for earliness, yield and yield components, fiber traits and yarn properties in a half diallel cross of cotton. Seven parental varieties, namely; Pima 87, Tamcot C.E.. Sea Island, Giza 86, Giza 70, Giza 83 and Giza 77 were crossed in a diallel fashion, excluding reciprocals, to produce 21 FI hybrids. The parents along with their F\ hybrids were evaluated in 2001 season for 29 characteristics including earliness, yield attributes, fiber and yarn traits.
The results indicated that mean squares due to entries and crosses were highly significant, indicating that parental genotypes as well as their F\ crosses exhibited reasonable degrees of variability for all studied traits. Parents vs. crosses mean squares as an indication to average heterosis overall hybrids was significant and pronounced for all traits, except for days to first flower, lint % and fiber stiffness, showing that heterosis effects were not pronounced for the three traits. Significant desirable negative or desirable positive heterosis relative to better parents were observed in some F\’s of all studied traits.
Specific combining ability (SCA) was highly significant for all traits and also general combining ability (GCA) was highly significant, except for yam appearance, revealing the important role of both additive and non-additive gene effects in the inheritance of these characters > except for yarn appearance where non-additive was the important.