Heterosis and combining ability studies for improvement of seed cotton yield and fibre quality traits in inter and intraspecific hybrids of allotetraploid cottons

The present investigation was carried out at college farm, College of Agriculture, Rajendranagar, Hyderabad to study the combining ability and heterosis for quality and yield characters in cotton. Further an attempt was made to trace out the best parents and crosses for future breeding programmes. In this direction seven lines and four testers were crossed in LxT mating design to generate 28 hybrids and evaluated with check NHH44 to know the combining ability of parents and crosses. The estimates of the components of variance and their ratios indicated the preponderance of non additive gene action for days to 50% flowering, number of monopodia per plant, number of sympodia per plant, number of bolls per plant, boll weight and seed cotton yield per plant, whereas non additive gene action was observed for the fiber quality traits viz., 2.5% span length, uniformity ratio, micronaire value and bundle strength. Based on gca effects the lines, CPD 420 and among the testers, HAG 1055 were identified as best general combiners for yield which were also observed to be good combiners for one or other fibre quality characters. The crosses involving the lines L604, LK 861 and MCU 17 among the testers were identified as best combiners for earliness. Based on sca effects the intra specific crosses, Galama x MCU 17 (G.hirsutum x G. hirsutum) and CPD 420 x HAG 105 (G.hirsutum x G. hirsutum) exhibited positive sca effects for bundle strength. Studies on heterosis revealed that the intraspecific cross CPD 420 x HAG 1055 were identified as promising heterotic hybrid for seed cotton yield and boll number an interspecific cross Galama x Suving were identified as early maturing along with high bundle strength and seed cotton yield.