Evaluation of genetic diversity of some Nigella sativa L. genotypes using Agro-morphological characteristics

This study was performed to investigate genetic diversity and relationships among morphological traits in 21 genotypes of Nigella sativa L., in a completely randomized design with four replications. Morphological traits included seed yield/plant, biological yield, follicle number, seed number per follicle, 1000- seed weight, number of stem branches, follicle weight, plant height and harvest index. Results of analysis of variance showed significant differences for all studied traits (p < 0.01) except harvest index. Phenotypic and genotypic coefficients of variation were high for most traits indicating high diversity of the studied traits. Seed yield varied from 63.34 g in genotype of Shiraz to 147.36 g in genotype of Zabol 1. Correlation coefficients among traits showed that seed yield/plant had a significant and positive correlation with biological yield, seed number per follicle, plant height, number of stem branches and harvest index. Results of stepwise regression analysis for seed yield showed that biological yield, seed number per follicle, number of stem branches and harvest index were entered into the model, respectively, and 95 percent of total variation of seed yield was justified. Path analysis showed that biological yield and seed number per follicle had the highest direct effect on seed yield per plant. Factor analysis revealed three factors that justified 94.12 percent of the total variation among studied traits. These factors were respectively named as efficiency factor (seed yield and biological yield), yield component factor (number of stem branches and follicle number per plant) and follicle factor (follicle weight and seed number per follicle). According to the cluster analysis, 21 genotypes were classified into 3 groups and there were significant differences among the groups especially in terms of seed yield, follicle number per plant and seed number per follicle. Consequently, crossing between superior genotypes of different clusters and testing their progeny through breeding and selection programs may result in production of cultivars with desirable agronomic characteristics.