Singh, Rajesh KumarYadav, Agnivesh2022-02-022022-02-022021-09-28Agnivesh Yadav 2021. Studies on Variability and Genetic Divergence in Onion (Allium cepa L.). M.Sc. Thesis. 137p.https://krishikosh.egranth.ac.in/handle/1/5810181551The present investigation entitled “Studies on Variability and Genetic Divergence in Onion (Allium cepa L.)” was conducted at vegetable research farm, BUAT, Banda during rabi season 2019-20 to determine the extent of variability, estimate correlation coefficient among the important economic traits, find out the direct and indirect effect on yield and determine the information and genetic divergence in onion genotypes for various traits. The experiment was conducted in RBD with three replications with twenty genotypes of onion. The observations were recorded on ten randomly selected plants for the characters viz.plant stand at maturity, plant height (cm) at 75 DAT, number of leaves/plants at 75 DAT, neck thickness at 75 DAT, equatorial bulb diameter (cm), polar bulb diameter (cm), P: E ratio, 20 bulbs weight (kg), average bulb weight (g), double (%) on number basis, bolters (%) on number basis, rotten (%) on number basis, days to maturity at 60-70 % neck fall, days to harvesting after transplanting, thrips/plant, stemphylium blight (intensity %), total soluble solids (%), gross yield (kg/plot), gross yield (q/ha), marketable yield (kg/plot), marketable yield (q/ha). The analysis of variance indicated highly significant differences among the genotypes for all the characters during the experiment. Based on the per se performance the genotype/variety NHRDF Red-4, performed superior regarding most of the traits, but the genotype Sukh Sagar taken minimum duration and mature only in 80 days after transplanting, it harvested approximately 30-40 days before if compare to others genotypes and also yielded well, so that this variety can be also recommend for cultivation in Uttar Pradesh. The estimates of PCV were higher than the corresponding GCV for all the traits. High PCV were observed for various characters viz, double percent on number basis, bolters percent on number basis, rotten percent on number basis, stemphylium blight intensity, thrips per plant, marketable yield (kg/plot), gross yield (q/ha) and bolters percentage on number basis. The GCV was high for various characters viz., double on number basis, bolters on number basis, rotten % on number basis, gross yield q/ha, marketable yield kg/plot. The high heritability recorded for P: E ratio, average bulb weight, days to maturity 60-70 % neck fall, gross yield (kg/plot), days to harvesting after transplanting, and marketable yield (q/ha), during the experiment maximum genetic advance as percent of mean was recorded for number of leaves per plant at 75 days after planting, double (%) on number basis, bolters (%) on number basis, rotten (%) on number basis, gross yield (q/ha), marketable yield (kg/plot).The magnitude of genotypic correlation has been found higher than the corresponding phenotypic correlation for all the traits that indicated inherent association among various characters. The gross yield (kg/plot) showed highly strong positive association with plant height (cm) at 75 DAT, number of leaves/plant at 75 DAT, neck thickness at 75 DAT, equatorial bulb diameter (cm), polar bulb diameter (cm), P: E ratio, 20 bulb weight (kg), average bulb weight (g), and thrips/plant. The genotypic path coefficient analysis of different yield contributing and associated traits on gross yield kg/plot revealed that traits viz., average bulb weight (g) has the highest positive direct effect followed by P: E ratio, equatorial bulb diameter (cm), number of leaves/plants at 75 DAT, rotten (%) on number basis, days to maturity at 60-70 % neck fall, days to harvesting after transplanting, thrips/plant and TSS (%). It indicated that possibility of effective improvement on onion bulb gross yield through these components could be achieved. The highest inter cluster divergence was observed between genotypes of cluster III and V, hence the crosses between the genotypes of these clusters can be tried for improvement of yield.EnglishThesis