Deciphering trait diversity in rainy-season onion: a comprehensive evaluation of morphological, nutritional,...

The present study employed a comprehensive multi-traits-based approach to evaluate thirty-one onion genotypes for morphological, biochemical, mineral, and molecular traits with the objective of identifying nutritionally superior genotypes suitable for rainy-season cultivation. Substantial genotypic variability was observed for major quality traits, including total phenols (172.76-446.73 mg/100 g FW), flavonoids (138.40-627.07 mg/kg FW), total antioxidants (FRAP) (1284.15-5538.31 µmol/100 g FW), pyruvic acid (1.33-11.65 µmol/g FW), total sugars (2.42-6.76%), reducing sugars (1.28-3.91%), non-reducing sugars (0.42-4.86%), total soluble solids (8.3-14.3°Brix), anthocyanin (2.87-44.18 mg/100 g DW), moisture content (85.36-89.13%), dry matter (10.87-14.64%), and mineral composition. Multi-trait donor genotypes combining yield, biochemical and mineral traits were identified through integrated PCA, PCA biplot and clustering analyses, with DOGR-2103 emerging as a key superior genotype. DOGR-2104 and DOGR-2101 also exhibited desirable combinations for yield and quality traits, while DOGR-2119 and DOGR-2114 were associated with quality and mineral traits. SSR marker analysis further identified RHRO-2022-10 and DOGR-2107 as genetically distinct genotypes with potential utility in molecular breeding and hybridization programs. In addition, principal component analysis revealed strong positive associations among sugars, total soluble solids, dry matter, and antioxidant-related traits, indicating their utility in selecting genotypes suitable for enhanced nutritional quality, processing efficiency and storability. In contrast, moisture content exhibited an inverse relationship with most of the quality attributes, highlighting the importance of developing low-moisture and high dry-matter rainy-season genotypes for improved storability and processing quality. Further, the identified trait-specific superior and genetically diverse donors represent valuable breeding foundation for developing nutritionally rich high quality onion cultivars suited to rainy-season. It also highlights the potential of bio-fortification for enhancing market value and consumer preference for both fresh consumption and processing in onion.