Critical nitrogen ranges for growth stages of tomato in soilless culture under greenhouse conditions in the tropics

Abstract

ABSTRACT Indiscriminate use of soluble fertilizer in hydroponics affects yield and quality of tomato (Solanum lycopersicum L.) and could contribute to environmental pollution. The study was conducted to determine the critical nitrogen dose, and corresponding tissue nitrogen range, at growth stages of hydroponically (coco-peat bag culture) grown tomato under tropical, semi-intensive, greenhouse conditions where mean day and night temperatures were 28–32 and 25–28°C, respectively, and mean relative humidity was 75–80%. Critical N application rates to obtain maximum yield for vegetative, early reproductive, middle reproductive and late reproductive stages were 10, 50, 90, and 140 mg/plant/day, respectively, providing critical plant tissue N concentrations at 5, 3.5, 4, and 4.3%, respectively. Application of the critical N dose at each growth stage will optimize yield and quality of tomato while reducing loss of nitrate to the environment.