Role of Nitrogen in Tomato Production

Nitrogen is a key component of enzymes, vitamins, chlorophyll and other cell constituents, all of which are essential for crop growth and development. It is thus one of the most important nutrients required for high tomato crop yields.

Nitrogen effect at growth stages

Stage Nitrogen effect
Establishment Promote strong early growth
Vegetative Growth Ensure continued growth
Flowering - Fruit Set Maintain plant growth and maximize flower numbers
Fruit Ripening - Maturity In reduced amounts to maintain fruit fill
See more on Tomato Growth Stages.

General guidelines for Nitrogen application

Crops remove around 4.8 – 5.3lb for every ton of fruit produced. High rates of 223lb/ac or above are needed for average 44.6t/ac field crops. However, too much nitrogen can depress yields so it is important to confirm rates following local trials. Nitrogen form is particularly important in the tomato crop and it is critical to maintain a good balance between ammonium and nitrate forms to maintain fast growth and crop productivity.

Nitrogen deficiencies in Tomato

Tomato plants are thin and upright in appearance when nitrogen is deficient. Leaves are small and pale green to yellow in color. Symptoms are first seen in the old leaves and gradually progress to new growth. If severe, the older leaves develop a purple color before dropping from the plant. Flowers may fall prematurely and fruit that develop are smaller than usual. Excess nitrogen results in dark leaves, luxuriant growth, less flowers and plants that are more susceptible to disease and moisture stress. Fruit set is reduced and fruit color is poor. Ripening is delayed due to a suppression of K and Mg.

See more about nitrogen and other nutrients deficiencies in tomatoes on Tomato Crop Nutrition.