Role of Boron in Onion Production
Boron is involved with carbohydrate metabolism and protein synthesis.
It also plays a key role in calcium movement within the plant.
Trials in Brazil confirm the positive effects that boron has on yield.
Boron also influences storage quality on onions. This could be associated with the micronutrient’s role in improving calcium accumulation in the bulb.
Boron effect at growth stages
| Stage | Boron effect |
| Pre-Planting | Ensure good shoot growth |
| Vegetative Growth | Ensure photosynthetic growth is not limiting |
| Bulb Formation | To maintain leaf growth |
| Bulb Fill | To improve storage quality and calcium uptake |
See more on Onion Growth Stages.
General Guidelines for Boron Application
Boron is one of the essential micronutrients for onion production and should not be limiting. While is quickly taken up from the soil, it is relatively immobile in the plant, so foliar sprays are often more effective. It is important to maintain the correct balance of calcium, nitrogen and boron in the soil. High calcium and high nitrogen levels can reduce boron uptake.
Boron Deficiencies in Onion
Young leaves develop yellow and green mottling. Older leaves yellow and dieback. Light yellow lines appear and develop into ladder-like transverse cracks on the upper surfaces of older leaves. They become brittle and deep green in color. Plants can be stunted or distorted. Deficiencies are most common on low pH and sandy soils as it is readily leached.
