Estimation of Heterosis in Cotton Genotypes for Yield Performance at Multan
Authors: Wahid Muhammad Atif , Khan Muhammad ldrees , Zhongxulin  
Published: January 2024

Abstract
The present study was conducted with the aim to find out the best general and specific combiner, type of their gene action, hetterotic effects, correlation and path coefficient among morphological, yield and yield contributing and fiber traits through line x tester mating design. In this research work 6 line parents and 6 tester parents along with their 36 F1 generation were studied. The traits i.e. days to first flower, flower shedding (%), boll formation, boll opening, 1st monopodial node number plant-1, 1st sympodial nodes number plant-1, number of monopodial branches plant-1, boll shedding (% age), number of leaves plant-1, plant height, total number of fruiting points plant-1, number of bolls harvested plant-1, boll weight, seed index, harvest index, biological weight plant-1, GOT %, fibre length (mm), fibre strength, micronaire value, fibre mean length, upper half means length and fibre uniformity index (%age) were studied. Results of gene action revealed that flower shedding, number of sympodial branches plant-1 and number of leaves indicated greater value than 1 revealing over dominance type of gene action at both locations. Total number of fruiting point, number of harvest bolls, flower shedding, number of sympodial branches, boll opening, GOT% and fiber strength showed a greater GCA at CCRI MULTAN . Maximum SCA effects were observed in traits i.e. boll formation, boll opening, number of monopodial branches, number of leaves, plant height, fruiting points, boll weight, seed cotton yield, biological weight and staple length. Heterosis results showed that days to first flower, flower shedding, boll formation, sympodial node number, plant height, fruiting points, number of bolls, seed cotton yield, GOT% and staple length had maximum significant mid heterosis at both locations. The traits including flower shedding, boll formation, sympodial node numbers, number of sympodial branches, boll shedding, plant height, fruiting points, number of bolls harvested, boll weight, seed cotton yield and upper half mean length indicated maximum standard heterosis at both locations. Correlation results indicated that boll shedding, boll formation, boll opening, sympodial node number, number of bolls harvested, boll weight, plant height, GOT%, fiber strength, micronaire value, seed index and seed cotton yield had positive correlation at both locations. Path analysis results indicated that flower shedding, boll formation, boll opening, sympodial branches, fruiting point and boll weight had positive and direct effect on seed cotton yield at both locations. GOT%, staple length and micronaire value showed negative and direct effect at both locations. For estimating genetic diversity 100 simple sequence repeats (SSR) markers were used on 12 parental genotypes. Only 13 markers yielded polymorphic fragments. Genetic diversity ranged from 41.55-73.81. The genotypes Emian-24 and Yumian-1 showed 62.53% similarity. The local line Lumian-21, Gamian-23, Xiangmian-13 showed maximum genetic diversity 73.81%. On the basis of above mentions results it is concluded that the genotypes showing best performances and countable genetic diversity can be used as a potential material for the development of high yielding and desirable fiber characteristics genotypes. Berger et al. (2015) conducted an experiment using eight cotton parents and concluded significant GCA and SCA effects for most of fiber quality trait as well quality traits. Among all parental genotypes; Texas A & M university lines performed for the improvement of fiber length and strength as specified by GCA effects. Natera et al. (2015) carried out studies using six standard varieties of upland cotton and examined the general and specific combining abilities. All the traits exhibited significant differences for GCA effects in parents and SCA effects in hybrids except for seed cotton yield that showed non-significant results. The mixtures of additive and non additive effects were observed for all traits.