Managing Taste and Pungency of Onion Bulbs

Taste and pungency of onions are key quality characteristics of this crop. They vary among types and cultivars. Pungency is largely due to the level of sulfur - based non-protein amino acids they contain. Sweetness can be assessed by the levels of sugars in the bulb. Although measurement of these elements can be difficult, it is well known that good nutrition is essential to managing taste and pungency of onion bulbs.

Crop Nutrition and Onion Bulb Taste and Pungency

Sulfur and Onion Pungency

Sulfur is critical to the taste and pungency of the bulb. Supplies need to be tailored to suit the desired market requirement. Sulfur can also improve skin strength and color, and has a marked effect on the pungency of the onion through increasing the pyruvic acid content of the bulb. Therefore, it is important to use the right soil and an appropriate rate and timing of sulfur that satisfies market demands.

Sulfur and Sugar Content

Sulfur also has a marked effect on bulb sugar content, so soil type and use of sulfur as part of a nutritional program have to be carefully considered in order to meet market requirements. For example, sweet onions benefit from being grown in low sulfur soils and should have low S-fertilizer regimes with most of the S applied early season to minimize uptake into the onion bulb.