Estimates of genetic variability and correlation coefficient for yield and its traits in black cumin (Nigella sativa L.) Genotypes in South Wollo Ethiopia

Black cumin (Nigella sativa L.) is a valuable annual spice used in food, cosmetics, and industrial products. However, productivity is limited by the lack of improved varieties, mainly due to insufficient knowledge of the genetic diversity within Ethiopian black cumin populations. A study was conducted to assess genetic variability and interrelationships among traits related to seed yield in various black cumin genotypes. Twenty-five genotypes were tested using a 5x5 simple lattice design in Hara, Tehuledere district, Ethiopia during the 2022/2023 growing season. Analysis of variance revealed significant differences for most parameters, except stand count at harvest and thousand seed weight. Broad-sense heritability (H²) and genetic advance as a percentage of the mean (GAM) ranged from 8.24% for days to 90% maturity to 89.56% for the number of tertiary branches per plant, and 4.51% for days to 90% maturity to 84.85% for the number of tertiary branches per plant, respectively. High to moderate estimates of genetic and phenotypic coefficients of variation (GCV and PCV), heritability, and GAM were observed for the number of tertiary branches per plant, number of flowers, number of capsules, biological yield, seed yield, and harvest index. The results also showed significant positive correlations between seed yield and various traits, including plant height, number of primary and tertiary branches, flowers, capsules, and seeds per capsule, biological yield, and harvest index, at both the genotypic and phenotypic levels. The study concluded that significant genetic variability exists, offering potential for targeted selection to enhance specific traits.