Genotypic variability and stability of fibre yield components in kenaf (Hibiscus cannabinus L.)
Multi-environment yield trials (METs) are essential to reduce the challenges of the genotypes × environment interaction (G × E) in identification of promising genotypes. Therefore, this study estimated genetic variability, broad-sense heritability (h2b), genetic advances (GA) and repeatability as well as stability of core and bast fibres yield of 33 kenaf genotypes evaluated across six locations. The varieties were grown in an experiment laid out in randomized complete block design with three replications in 2016. Mature plants were harvested, retted and dried. Core fibre (CF) and bast fibre (BF) were weighed and data collected were subjected to analysis of variance (ANOVA) separately and across locations. Genetic variances, broad-sense heritability (h2b), genetic advance (GA) and repeatability were estimated for both traits. The G × E was assessed using joint regression analysis. Highly significant variation existed for both core and bast fibre yields among the genotypes in each of the locations. Phenotypic parameters were higher than those of the genotypes for both core fibre weight (CRW) and bast fibre weight (BSW). Broad-sense heritability was 82% for CRW and 66% for BSW while GA was 53.7% and 8.8% for CRW and BSW, respectively. Combined ANOVA showed significant differences for genotypes, environments, and G × E for CRW and BSW (p<0.001). Partitioning of G × E showed that only Gen × Env. (linear) was significant (P<0.05). Genotypic variance was 85% of the phenotypic variance for CRW, but only 32% for BSW. Hence, environmental effect was more on the CRW than BSW. Inheritance of the CRW and BSW is genetic because of their high heritability. Genetic advance and repeatability were higher for CRW than BSW. Based on high heritability with high GA for CRW, gene action governing inheritance of CRW is additive. Both additive and non-additive gene actions are responsible for BSW because its high heritability but low GA. Progress can therefore be made in selection for CRW than BSW in kenaf improvement programmes. Linear response of genotypes on environments accounted for the major part of total variation for the two types of fibre yield. Genotypes A-60-282-15, AC-313-293, AU-2452-5A and Cuba 108 are adapted to favourable environments while AU-2452-43, AU-24526, 2QQ 171 and AU-7192 are adapted to less favourable environments both in CF and BF yields.
Keywords: Bast fibre, Core fibre, Genotype, Gene action, Regression analysis, Stability