Components of Genetic Variation for Yield and Fibre Quality Characters in Upland Cotton ( Gossypium hirsutum L.)

The experimental material consisting of different generations of single tester analysis was grown in a randomized complete block design and was evaluated for seventeen characters related to yield, fibre quality, earliness and plant type. The analysis of variance for the test of epistasis based on scaling tests Ai and Bi revealed the presence of epistasis for most of the characters studied. The additive genetic component, dominance genetic component, and their relative contribution towards genetic variation in the population were estimated. These results indicated the involvement of additive as well as non-additive gene action in the inheritance of various characters. The magnitude of additive genetic component was higher than dominance genetic component for number of monopods, average internodal length, number of bolls, number of fruiting points, boll setting percentage, days to maturity, harvest index, fibre strength and fibre fineness whereas for number of sympods, plant height, yield of seed cotton per plant, boll weight, ginning outturn, seed index, lint index and 2.5% span length, the magnitude of dominance component was higher and degree of dominance showed over-dominance. On the basis of different components estimated, the appropriate breeding methods for improvement of yield and fibre quality with short compact and early maturing plant type have been discussed.