The present investigation was carried out at Sakha Agriculture Research
Station, during the three successive seasons of 1999, 2000 and 2001. Six varieties of
cotton were used in this study. These varieties were: Giza 70, Giza 88, Giza 76, Giza
86 (An Egyptian varieties), Karshenseky-2 "Kar. 2" (Russian variety) and Pima S6 (An
American Egyptian variety). Selection for increasing lint index and its indirect effect were studied on
backcrosses and F2 generations of some cotton varieties (Giza 70, Giza 88, Giza 76,
Giza 86, Karshenseky-2 and Pima S6). A selection intensity of 5% was used with
direct selection. The mean squares from the analysis of variance were significant for
genotypes and parents for most studied traits. Crosses and parents virsus crosses
mean squares were significant for seed cotton yield/plant, lint yield/plant and fiber
length and insignificant for all studied traits, respectively. Positive direction in F2 was
accompanied by significant increases of lint percentage in G 70 x Karshenseky-2, G.
88 x Pima S6 and G. 76 x Karshenseky-2, while it was insignificant for boll weight and
seed index in most F2 crosses. Backcrosses showed insignificant increases for most
traits. The negative direction in backcrosses revealed insignificant decreases for all
studied traits in most crosses, while, F2 populations illustrated significant decreases
for lint percentage in most crosses and it was insignificant for boll weight, seed index
and some fiber traits. Most backcrosses and F2 populations had considerable
amounts of the actual genetic gain for lint index, lint percentage, seed index, boll
weight, in G 70 x Karshenseky-2, G. 88 x Pima S6 and G. 76 x Karshenseky-2, for
seed cotton yield and lint/plant and in G. 70 x Karshenseky-2 for most fiber traits in
backcrosses only. No differences between the predicted and the actual genetic gains more
observed for lint index on one side and pressley index, 50% span length and 2.5%
span length on the other side as indirect effect of selection, indicating an independent
inheritance of lint index.