How to improve onion quality

Nutrition programmes based on crop nutrient needs are key to influencing both yield and quality. Crop nutrition influences dry matter content, firmness and storability as well as taste and pungency, all important factors in determining the quality of onion crops.

Balanced nutrition is needed for quality onions

Macronutrient distribution in onions

Nitrogen excess can cause quality issues

Nitrogen has greatest effects on onion yield although too much nitrogen softens the bulb and increases storage rot diseases.  However nitrogen can also influence quality by helping to increase skin thickness.

Effect of nitrogen rate on onion skin quality

Phosphate has a positive effect on storage quality

Phosphorus has a positive effect on storage quality of onions and garlic, especially when high rates of nitrogen have been used.

Effect of phosphate  on onion storability

Potassium allows higher rates of nitrogen to be applied

The use of potassium allows growers to maintain high rates of nitrogen for yield with reduced risk of storage problems such as rots or sprouting. 

Effect of potassium on onion bulb dry matter

Calcium is important to ensure good quality onions

Calcium is particularly important for bulb density, integrity and long-term storage with minimal disease problems. Magnesium also has a role to play in improving storage quality characteristics.

Effect of calcium and magnesium on onion storage

Boron helps calcium uptake

Boron has been shown to improve storage quality, which could be associated with the micronutrient’s role in improving calcium accumulation in the bulb.

Effect of boron on onion storage quality