Genetic Analysis of Yield and its Components of Some Egyptian Cotton (Gossypium barbadense L.) Varieties

Abstract

3 Abstract: Seven Egyptian cotton genotypes were crossed using scaling test analysis during summer 2004 to 2005 and evaluated in 2006 summer season at the Agricultural Experimental Farm of Al-Alzhar University, Assiut. The experiment was grown in a Randomized Complete Blocks Design with three replications. The means of the six generations; P , P , F ,F , BC and BC of four cotton crosses recorded for days to 50% flowering, first 1 2 1 2 1 2 fruiting per plant, no. of fruiting branches per plant, days to 50% maturity, no. of open bolls per plant, boll weight, seed-cotton yield per plant, lint yield per plant and lint percentage, were subjected to scaling test and six parameters method to detect epistasis and estimates of m, d, h, i, j and L parameters. Results showed that the additive - dominance model was adequate to demonstrate the genetic variation and it important in the inheritance of most studied traits. Non-allelic gene interaction was operating in the control of genetic variation in most studied traits. The epiststic effects, additive x additive (i) and dominance x dominance (h) were highly significant in most cases. The signs of (h) and (L) were opposite in all studied traits for most crosses. Also, the inheritance of all studied traits was controlled by additive and non-additive genetic effects, but dominance gene effects play the major role in controlling the genetic variation of the most studied traits. Significant negative heterosis relative to mid-parents was found for both characters, first fruiting branch per plant and days to 50% maturity in all crosses while, significant negative heterosis above the better parent was found for first fruiting in both crosses no. 1 and 4, days to 50% maturity in cross no. 4. Inbreeding depression estimates were found to negative and highly significant for days to 50% flowering, first fruiting per plant and days to 50% maturity. The phenotypic (PCV) were higher than its corresponding (GCV) for all studied traits, except days to 50% maturity.