Abstract
Onion is one of the most widely cultivated high-value vegetables on the globe. The study of variability and genetic divergence in this crop will facilitate judicious parent selection for future breeding. The present study incorporated 20 onion genotypes to determine the genetic variability and diversity through morpho-physiological and molecular markers. The genotypes were tested for two consecutive years to determine the effects on yield-attributing and bulb-quality traits. Diversity at a molecular level with 31 simple sequence repeat (SSR) markers was determined. Adequate genetic variability existed among the genotypes, with a predominance of additive gene action regarding the inheritance of most of the characteristics. Principal component (PC) analysis detected seven PCs contributing to more than 87% of the genetic diversity in the genotypes. Total yield (kg/plot), Grade 'C' bulb (equatorial diameter of the bulb between 3.5 and 4.5 cm), individual bulb weight (g) and phenol content were detected as characteristics positively associated with the first two PCs. A total of 16 primers were amplified, and they produced 32 alleles in the genotypes. Genetic diversity at the morphological and molecular levels indicated moderate diversity among the tested genotypes, with the dissolution of the genotypes into six and three clusters, respectively. The present study on onion facilitates the selection of diverse parents that can generate desirable segregants in future breeding programmes.