Effects of the okra leaf, nectariless, frego bract and glabrous conditions on yield and quality of cotton lines

Effects on yield and quality associated with the glabrous leaf, frego bract, okra leaf and nectariless genes (singly and combined) were studied under two insecticide spray regimes (heavy and light) in field experiments repeated over three seasons. Under the heavy spray regime there were few consistent differences between mutant genotypes and the normal except for low yields associated with the glabrous leaf, nectariless, frego bract genotype and the okra leaf genotype. Under the light spray regime, genotypes containing the okra leaf gene and/or the nectariless genes were associated with higher yields than the normal and genotypes containing glabrous leaf and/or frego bract genes were associated with lower yields. Positive epistatic interactions occurred in a number of instances including the okra leaf gene in the glabrous hair, normal bract background under heavy spraying, and with all backgrounds under light spraying, and for glabrous leaf in both the okra normal and okra frego backgrounds under heavy spraying. Nectariless also interacted positively with the normal leaf, normal hair, normal bract background under light spraying. Pronounced negative epistatic interactions only occurred in the light spray regime, and included glabrous leaf in all backgrounds, and frego bract in all backgrounds except the normal leaf, normal hair. The mutant genes had only minor effects on lint quality. The implications of the results for breeding and pest management are diseussed.