Role of Zinc in Onion Production
Zinc is important for the development and function of growth regulators (e.g. auxin) that influence internode elongation.
It is also involved in chloroplast development and thus important for photosynthesis.
Young plants are particularly sensitive to zinc deficiencies and trials in India show that use of zinc can improve seed germination.
Zinc can also improve seed yield, as trials in India show.
Zinc effect at growth stages
| Stage | Zinc effect |
| Pre-Planting | Ensure good shoot growth |
| Vegetative Growth | Ensure photosynthetic growth is not limiting |
| Bulb Formation | To maintain leaf growth |
| Bulb Fill | Less critical, but to maintain growth and prolong bulking |
See more on Onion Growth Stages.
General Guidelines for Zinc Application
Zinc uptake can be restricted by excessive use of phosphorus. Thus it is important that zinc and phosphorus are balanced, particularly during early stages of growth.
Zinc Deficiencies in Onion
Deficient plants are stunted and have twisted, outward bending leaves. Older leaves take on an orange mottled appearance. Younger leaves have a faint chlorosis and yellow striping. Bulbing can be delayed and crops may not store well. Problems are more common on high pH or calcareous soils or during cold, wet weather.
