Analysis of genotypic diversity in sesame (Sesamum indicum L.) based on some physiological characters

Genetic diversity among 30 sesame genotypes, collected from different parts of India, was studied using measurements of leaf area index (LAI) obtained 30, 45, 60 and 75 days after sowing (DAS), crop growth rates (CGR) estimated between the above leaf area measurements (i.e. 30 to 45 DAS, 45 to 60 DAS and 60 to 75 DAS), days to peak flowering, duration of flowering, duration from peak flowering to maturity and oil yield per plant. The normalised Euclidean distance was calculated from the data, and, independently, the Mahalanobis D2 statistics was calculated after dimensionality was reduced by pivotal condensation. The clustering pattern obtained by D2 analysis agreed closely with the dendrogram constructed from the Euclidean distance matrix. In general, the distribution pattern of genotypes in different clusters indicated that genetic divergence was not related to geographical differentiation. However, it was evident that a certain degree of genotypic divergence resulted from the geographic origin of the cultivars. Duration from peak flowering to maturity contributed most to the observed diversity, followed by days to peak flowering, duration of flowering, LAI at 30 DAS and 75 DAS, oil yield per plant and LAI at 60 DAS. Therefore, a greater emphasis should be laid on these characters in the selection of parents for further breeding programmes.