Five cotton varieties belong to Gossypium barbadense L. i.e. Giza 89,Giza 90 Giza 83, Pima S4 and Pima S6 were selected as parents and crossed in a half diallel pattern to evaluate general and specific combining ability effects (GCA and SCA) and heterotic effects for some agronomic traits i.e. boll weight (B.W.), seed cotton yield (S.C.Y.), lint yield (L.C.Y.), lint percentage (L.%), seed index (SI), length at 2.5% , strength g/tex and micronaire value (Mic). Analysis of variance revealed significant differences among entries for all traits studied except for B.W., S.I. and Mic in F1 and F2 generations as well as length at 2.5% in F2's generation which showed significant differences. The mean squares in both F1's and F2's for general combining ability (GCA) were insignificant for all traits except for S.C.Y. and L.C.Y. in F1's and F2's generations. Meanwhile, the mean squares for specific combining ability (SCA) were insignificant for all traits except S.C.Y. and L.C.Y. in both generations and strength g/tex in F1's generation which showed significant. The GCA/SCA ratio of variance components indicated that additive genetic variance was generally importance for B.W., L%, SI and Mic in the F1 hybrids and for B.W., L.C.Y., L.% and Mic in the F2 generation. Mid-parents heterosis values were significant and positive for S.

Plant breeder use yield traits to identify promising genotypes. This goal depends the magnitudes of genotype by environments and stability performance of genotypes. Therefore, twenty Egyptian extra long genotypes were grown in three locations under two years for yield, yield components earliness and fiber traits to identify promising stability genotypes. The genotype x environment interaction was significant for yield and fiber traits. It also noticed that variation due genotype x environment were further partitioned into linear and non-linear components. Genotype x environment linear was insignificant for all studied traits except for MC trait, insignificant of genotype x environment linear indicated that genotypes didn't differ genetically in their response to different environments. Pooled deviation mean squares were significant for all studied traits , indicated that the major components for differences in stability were due to deviation from the linear function. Therefore, it could be concluded that the relatively unpredictable components of the interaction maybe more important than the predictable components.The results illustrated that lines 3, 5 and 15 were stable for seed cotton yield (x -

The new promising cross Giza 77x pima s6 is an extra long extra fine Egyptian cotton promising cross while was produced through artificial hybridization between the parents Giza.77 and Pima S 6 . The new promising cross is characterized with its extra fine, extra long and very strong fiber about 46-5 gram / tex, 36.5-38 mm upper half mean, 3.3 micronaire reading 105 -120 millitex for hair weight and over 3000 yarn strength. Also the lint percentage is about 33-35%. This promising cross is characterized with high yield. This promising cross is characterized by its resistance against Fusarium oxysporum and f. vasinfectum. This promising cross could be the best alternative to Giza 45 and Giza 87.