Abstract
Increase in productivity and selection procedures chiefly depend upon genetic control of yield related traits, combining ability of the genotypes for concerned characters and association of these parameters among themselves and with the final yield. Single and three way crosses in cotton were analyzed for genetic behavior, combining ability, heterosis and correlation of various traits related to boll (synonymously known as within boll yield traits) and fibre quality. The experiments were carried out at the Department of Plant Breeding and Genetics, University of Agriculture, Faisalabad. Crosses were made using line x tester mating design. All the genotypes showed highly significant variability with respect to all the parameters studied. Variances for both general combining ability (GCA) and specific combining ability (SCA) were significant for most of the traits however variances due to SCA were higher than variance due to GCA for all the traits. Likewise dominance variance (D) was higher than additive variance (A) which indicated dominant genetic behavior of the traits. The line BH-160 was found to be the best general combiner for most of the traits like average boll weight, number of seeds per boll, seed mass per boll, lint mass per boll, seed volume, seed surface area, seed cotton yield per plant and fibre fineness. Among testers, CIM-496 exhibited the highest GCA effects for boll weight, seed mass per boll, lint mass per boll and seed cotton yield per plant, while for number of seeds per boll, staple length and fibre strength, S-12 was considered the best. Highest SCA effects for boll weight, number of seeds per boll and seed mass per boll were displayed by (NIAB-228 x BH-160) x Reshmi-90. Most of the boll related traits revealed significant positive correlation with seed cotton yield.