ESTIMATION OF COMBINING ABILITY AND HETEROTIC POTENTIAL FOR WITHIN-BOLL YIELD TRAITS UNDER LEAF CURLING DISEASE INFESTATION IN COTTON

Abstract

ABSTRACT Cotton leaf curling disease (CLCuD) is the major threat to cotton production and quality in many cotton producing countries including Pakistan. The objective of current work was to identify the potential genotypes which perform well under the disease prevalence through manipulating the within-boll yield traits. For this purpose; six genotypes possessing broad genetic base were selected and crossed in all possible combinations. Crossed seeds from 30 combinations and selfed seeds from 6 parental genotypes, thus produced, were grown along with parents under field conditions in randomized complete block design replicated thrice. Analysis of variance depicted significant differences among genotypes for all the traits under consideration. Strong evidences for the prevalence of non-additive genetic behavior of the traits were recorded. The genotype MNH- 886 was found as good general combiner for lint mass per boll, seed mass per seed and CLCuD index; MNH- 888 for lint mass per seed and seed cotton yield while VH-61 for seed mass per boll and seed number per boll. Results pertaining to specific combining ability effects revealed that the most desirable combinations for various traits were; FH-113 × FH-2015 for lint mass per boll and seed number per boll, MNH-888 × IR-4 for lint percentage and lint mass per seed, MNH-888 × VH-61 for seed cotton yield and CLCuD index. Most of the hybrids showed greater mid parent heterosis than that of better parent. Results from the current study supported the hypothesis that seed cotton yield and quality can be enhanced through exploitation of withinboll yield components in CLCuD tolerant cultivars. Key words: Bt-cotton, CLCuD, combining ability, heterosis, within-boll yield components.

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