The present work was carried out during two successive seasons 2001 and
2002 at Salcha Agricultural Research Station to study general and specific combining
abilities for the Egyptian cotton varieties: Giza 86. Giza 85, Giza 90 and Giza 83
(Lines) and Giza 70. Giza 89 and the Russian variety Karshenskey (testers), aU
belong to GOS8ypium barbadense L. The dominance component of variance played a considerable role in
controlling most characters except for boll weight. lint percentage and lint in ex. this
was confirmed by low heritability values in narrow sense. The estimates of the proportional contribution of lines were hig er than
those of testers for all studied characters except for seed cotton yield per plll"t and
number of bolls per plant, while high estimates of the proportional contribution were
obtained from the lines x testers interaction for seed cotton yield per plant, Itnt yield
per plant and number of bolls per plants. For mean values of yield and its components, Giza 86(L,) shovred the
highest values for all characters, while Giza 90 (L3) possessed the lowest estimates
of most characters. From the components of variance, it was clear that the en"iro~mental
variance appeared to be of small effect on the expression of gene govemlng boll
weight, lint percentage, seed index and lint index, while It had highly effective seed
cotton yield per plant, lint yield per plant and number of bolls per plant. these results
were assured by heritability estimates in broad sense.