Unraveling the Biochemical Diversity in Short-Day Onion Genotypes

Crop production is directly associated with the improvement of germplasm, which is mainly reliant on genetic diversity. Diversity among various genotypes has been investigated employing a variety of statistical approaches. The most widely utilized of these methods for determining the genetic overlap of genotypes is multivariate. In the present investigation, a total of 27 onion genotypes/advanced lines/varieties comprising high and low total soluble solids (TSS) white onion lines along with red varieties were evaluated at the ICAR-Directorate of Onion and Garlic Research station. Data were recorded on seven biochemical parameters. In multivariate analysis, genotypes were clustered into three major groups: the first group comprised thirteen genotypes with high TSS; however, the second group (eight) comprised low TSS white onion genotypes, and in the third group (six), mostly red varieties were clubbed together. The analysis primarily focused on the trait TSS; it was significantly associated with the antioxidant assay 2, 2-diphenyl-1-picrylhydrazyl(DPPH) AE, while total sugar content was positively associated with the antioxidant assay 2, 2-azinobis (3-ethylbenzothiazoline- 6-sulfonic acid)ABTS. In principal component analysis (PCA), the first three principal components (PCs) with >1 Eigen value contributed 71.36% of the variability among genotypes. Characters with a maximum value at PC1 were total soluble solids (0.48), antioxidant capacity AE DPPH (0.46), and total sugar content (0.49). PC2 comprises total phenolic content (0.62) and total flavonoid content (0.62); for PC3, the major contributors were thiosulfinate content (0.82) and antioxidant capacity ABTS (0.32). From the findings of the present study, the best-performing high TSS lines can be used for advancement through strongly correlated traits using breeding strategies. These sorted high TSS lines (W-103, W-107, and W-123) (>22 °Brix.), high-sugar-content genotypes (W-108, W-111, and W-308), and W-361, which recorded high thiosulfinate content, can be advanced or used as parental material for the development of processing-suitable onion varieties.