ASSESSMENT OF GENETIC DIVERSITY AND YIELD OF SELECTED SESAME (Sesamum indicum L.) GENOTYPES IN WESTERN KENYA

Abstract

Sesame is one of the most important oilseed crops in the tropical and subtropical regions of the world. Despite its importance, sesame yields in Kenya is very low due to lack of improved and high yielding varieties as well as insufficient variety information regarding genetic diversity. The objective of this study was to evaluate the status of constraints in yield performance and diversity in morphological characters of sesame in Western Kenya. A descriptive survey design was used and data collected with the aid of a questionnaire. The study noted that most farmers (82.4%) haven’t received any information on sesame cultivation thus most of them (62.7%) reported seed yields below 400 kg ha−1. Sixty six percent (66.7%) of the respondents obtained seeds from local markets, 80.4% planted sesame as a mono-crop whereas 60.8% planted in rows. The most available accessions were Local white, Sudsim (advanced) and Local Brown. These three, plus other accessions collected from nearby locations were evaluated for seed yield, yield related characters and morphological traits. The analysis of variance revealed significant difference among the ten genotypes for all traits, indicating the presence of sufficient variability among the evaluated germplasm for seed yield and other yield contributing traits. Yield per hectare exhibited highly significant positive correlation with number of fruiting branches/plant, capsule length, number of capsules/plant, plant height, number of seeds/capsule, 1000 seed weight and seed yield/plant. Correlation analysis revealed the presence of highly significant positive association between seed yield and the yield related traits. A high level of genetic diversity based on morphological traits was observed. This could be attributed to a wide range of environmental conditions which induces variability through genotype by environment interaction. The dendrogram based on UPGMA cluster analysis did not separate the genotypes based on their geographical distribution instead genotypes grouped according to their morphological differences. PCA showed that the first four principal components were important and indicated that number of capsule/plant, number of fruiting branches/plant, seed yield/plant, leaf arrangement, leaf hairiness and flower color were the most important characters and hence were the most useful for distinguishing among sesame genotypes. Genotypes UG1 and KSS showed better yield performance across environments. The use of these genotypes in breeding programs would contribute to improved sesame varieties with a high seed yield. This research study therefore provides important insights into the populations of sesame genotypes in Western Kenya and constitutes a set of useful genetic background information that can be used as a basis for future breeding strategies and sesame improvement programs.