COMBINING ABILITY ANALYSIS FOR FIBRE QUALITY IN INTERSPECIFIC HYBRIDS OF COTTON

Name of the Author : M. KRISHNA MOHAN Title of the thesis : COMBINING ABILITY ANALYSIS FOR FIBRE QUALITY IN INTERSPECIFIC HYBRIDS OF COTTON Degree to which it is submitted : MASTER OF SCIENCE Faculty : AGRICULTURE Department : GENETICS AND PLANT BREEDING Chairperson : Dr. M. GOPINATH University : ACHARYA N. G. RANGA AGRICULTURAL UNIVERSITY Year of submission : 2011 The study was carried out during kharif 2010-11 at Regional Agricultural Research station, Lam Farm, Guntur with 54 hybrids along with their 15 parents (6 lines and 9 testers) to know the genetic variability, heritability, genetic advance, correlation and the magnitude of direct and indirect effects, combining ability and standard heterosis. The data were recorded on 14 economically important characters viz., number of monopodia per plant, number of sympodia per plant, number of bolls per plant, boll weight (g), seed index (g), lint index (g), ginning out-turn (%), 2.5% span length (mm), micronaire value (10 -6 g/inch), bundle strength (g/tex), uniformity ratio, fibre elongation (%), harvest index and seed cotton yield per plant (g). The analysis of variance revealed significant differences among the genotypes for all the characters studied indicating that the material used in the present investigation possessed sufficient variability. High heritability coupled with high genetic advance as per cent mean was observed for number of monopodia per plant, number of sympodia per plant, number of bolls per plant, boll weight, seed index, lint index, micronaire, harvest index and seed cotton yield per plant indicating the operation of additive gene action with little influence of environment. The character association analysis revealed that number of monopodia per plant, number of sympodia per plant, number of bolls per plant, boll weight, seed index, 2.5% span length, fibre elongation and harvest index were found to have significant positive association with seed cotton yield per plant. Further, the path analysis indicated that number of monopodia per plant, number of bolls per plant, boll weight, seed index, ginning out turn, 2.5% span length, micronaire, uniformity ratio, fibre elongation and harvest index showed direct positive effects on seed cotton yield per plant. The ratio of general combining ability variance to specific combining ability variance indicated the preponderance of non-additive gene action for most of the characters studied. The lines, ACH 703 E, RFS 3438, 0892 B and REBA B 50 and the testers, RHCB 001, DB 11, TCB 108, CCB 6 and BRAZIL were identified as good general combiners based on overall gca effects. The crosses 0892B X CCB 5, CNH 120 MB X RHCB 001and RFS 3438 X SUVIN showed positive and significant specific combining ability effects for seed cotton yield per plant along with few fibre quality characteristics. Significant positive standard heterosis compared to check was observed for seed cotton yield in two crosses viz., 0892 B X CCB 5 and 0892 B X DB 11. Thus in the present study the cross, 0892B X CCB 5 was identified as promising hybrid for high seed cotton yield per plant based on overall performance i.e., per se performance, sca effects and standard heterosis. But incase hybrids with good fibre quality characterstics CNH 120 MB X DB 11is superior to the above hybrids and the seed cotton yield is also on par with the check.These hybrid can be exploited for commercial cultivation after thorough testing in different environments for its superiority and stability.