Nutraceutical profiling of elite onion germplasm and breeding hybrids with improved nutraceutical quality

Onion (Allium cepa L) is a major reservoir of important nutraceutical ingredients. Herein, nutraceutical profiling of elite germplasm was assessed and hybrids with improved nutraceutical quality were selected. The nutraceutical components were screened through Fourier Transform Infrared Spectroscopy (FTIR) analysis (scan range 4000-400cm-1) followed by spectrophotometric/colorimetric quantification in oven dried bulb samples. Line × Tester (L×T) analysis was used to identify potential hybrids with better nutraceutical quality. Based on common functional groups obtained from FTIR analysis, as well as bulb color, the onion genotypes were categorized into six groups viz., white, yellowish brown, light brown, dark brown, brown and purplish brown. Results indicated that the purplish brown, yellowish brown and dark brown genotypes had maximum concentration of pyruvic acid, total flavonoids and total phenolic content, while vitamin C content showed weak association with color pigmentation. The onion variety 'Onion Swat' contained the highest level of pyruvic acid (17.18 μM) and 'MKS8823GO' had the highest vitamin C content (13.83mg/100mL). The L×T analysis revealed that out of 35 crosses, 'MKS-77127 × Onion Swat' and 'MKS-77127 × MKS777' were the best hybrids with improved nutraceutical quality. Further, observations for specific combining ability, general combining ability, genetic versus environmental variance, heritability and heterosis indicated that the studied parameters were genetically inherited and could be improved significantly by adopting an appropriate breeding strategy.