Role of Iron in Onion Production

Iron is associated with chlorophyll formation and photosynthesis.

Iron deficiency

Iron deficiency (left), complete nutrition (right)

Iron effect at growth stages

Stage Iron effect
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 Iron Application

Applications of iron, such as foliar or fertigation, can be used to increase early leaf production and crop productivity.

Iron Deficiencies in Onion

Generally, onions appear insensitive to iron deficiency, with most soils supplying adequate levels of iron to meet crop needs. Under extreme deficiencies, leaves become completely chlorotic and bleached.