Estimation of selection criteria through multi-year assessment of variability parameters, association studies and genetic diversity of Solanum khasianum CB Clarke

Solanum khasianum Clarke belonging to the Solanaceae family contains a steroidal alkaloid, solasodine which has commercial and medicinal importance. Solasodine acts as a starting material for the synthesis of steroid hormones, such as oral contraceptives and cortisone. In the present study, a total of 273 accessions were collected out of which 186 accessions rich in solasodine content (>0.8 %) were selected for the study. These selected lines were planted in bed size of 3.6 × 3.6 m in a randomized complete block design (RCBD) with plant to plant spacing of 60 cm with three replications during kharif 2018, kharif 2019, and kharif 2020 for which pooled data were analyzed. Analysis of variance revealed significant differences among the genotypes for all the studied characters revealing high variability among them. Highest GCV (Genotypic coefficient of variation), PCV (Phenotypic coefficient of variation) along with high heritability with high genetic advance was depicted in 100 fresh fruit weight and the number of fruits/plant indicating high variability due to additive genes action which makes it useful in the selection program. Low magnitude between GCV and PCV was observed in the trait plant spread indicating minimum environmental influence and high effect of environment was observed in 100 fresh fruit weight. Based on the genotypic and phenotypic correlation, the number of fruits/plant, plant height, plant spread, and fruit diameter was found to be significantly and positively correlated with100 fresh fruit weight. However, the solasodine content was negatively correlated with 100 fresh fruit weight and the number of fruits/plant. The path coefficient analysis suggested that the number of fruit per plant and plant spread were the direct contributing traits for the fruit yield. In contrast, days to maturity were the direct contributing factor via 100 fresh fruit weight for solasodine content. Diversity using Mahalanobis D² analysis revealed 80.54% variability which was contributed by the number of fruit per plant, 100 fresh fruit weight, leaf width, leaf length, plant spread, fruit diameter, and days to maturity. The present variability and multivariate analysis among the high solasodine content lines of S. khasianum will help in the breeding, conservation, and varietal development program of this industrially important crop. This is the first report on the variability parameters, association, and diversity study among 186 germplasm of S. khasianum.