Role of Copper in Onion Production
Copper has a key role to play in lignin formation.
It is also linked to chlorophyll performance.
Trials in Brazil show that copper can improve crop marketability by enhancing skin color.
Copper effect at growth stages
| Stage | Copper effect |
| Vegetative Growth | Ensure photosynthetic growth is not limiting |
| Bulb Formation | To maintain leaf growth |
| Bulb Fill | For good skin quality |
See more on Onion Growth Stages.
General Guidelines for Copper Application
Adequate supplies of copper are important for bulb skin and onion scale development, as a result of the element’s role in lignin production.
Copper Deficiencies in Onion
Tips of young leaves turn white and twist into a corkscrew or bend at right angles. Bulbs have thin, yellow outer scales, are less solid, and are often earlier maturing. Deficiencies are more common on organic or sandy soils and where excessive nitrogen rates have been applied.
