Temperature, nitrogen and sulfur fertility influence the flavor pathway in onion (Allium Cepa L.)

The effects of temperature and developmental age, nitrogen fertility, and nitrogen and sulfur fertility interactions on onion flavor were tested. Temperature and developmental age effects on onion flavor were tested by growing onions between 16.5 and 32.2 oC for 50 days and until maturity. Bulbs responded to increasing in temperature with increases in total bulb sulfur, pungency, and flavor precursors. The effects of nitrogen fertility were also studied. Total bulb sulfur, pungency and flavor precursors responded quadratically to nitrogen level, increasing and then decreasing as nitrogen levels increased. In a third study, nitrogen and sulfur nutrition were shown to interact, affecting the flavor pathway. At low levels nitrogen and sulfur interacted to affect most flavor parameters. Additionally, nitrogen and sulfur fertility were shown to influence the accumulation of different precursors, suggesting that the two nutrients regulate flavor precursor accumulation at different points within the flavor pathway.