Effect of nitrogen, phosphorus, potassium, magnesium and liming on the composition of tomato fruit

Abstract

Abstract Some aspects of the composition of tomato fruit from a 3 2 NK × 2 3 PMgCa factorial nutritional trial have been studied for four seasons. Increasing applications of potassic fertilisers significantly increased the titratable, total and combined acidities, potassium content, refractive index and specific conductivity of the expressed fruit juices. The effects of nitrogen were not so pronounced and, with respect to acidity, potassium content and specific conductivity, were influenced by the level of potassium applied. The potassium content and the acidity of the fruit juices were closely correlated. Nitrogen applications significantly depressed the sugar content of the fruit, but potassium and phosphorus had little effect. Phosphorus reduced the acidity, potassium content and specific conductivity, particularly at low potassium levels. Magnesium and lime had little effect on tomato fruit composition.