The effect of daily nutrient applications on yield, fruit quality, and nutrient uptake of hydroponically cultivated tomato

Daily nutrient additions reduced nutrient supply and concentration in the hydroponic solution without affecting fruit yield and quality of tomato 'Renaissance', grown during the winter of 2003-2004 and the summer of 2004. The results were compared to those obtained by the conventional EC-based plots. In the daily nutrient addition plot, all nutrients were supplied according to water uptake by tomato plants under three different application rates (Low, Medium, and High nutrient solution). The nutrient levels in the Medium treatment were reduced, except for sulfur, to 53-66% with respect to the EC-based treatment in the winter experiment and 73-77% in the summer experiment. Nitrogen and phosphorus concentration in the Low and Medium nutrient solution did not exceed 10 mg.L-1 and 3 mg.L-1, respectively, except for 30 days after the transplanting. The total amount of macro nutrient absorbed and dry weight accumulated by leaves increased with increasing nutrient supply. The yields from the Medium and High treatments were equal to the EC-based treatment. Daily nutrient addition increased soluble solids content and ascorbic acid, but it did not influence titratable acidity in fruits. It was estimated that the addition of 50 mg N.plant(-1).day(-1) is adequate to maintain normal growth by tomato plants, provided the water uptake was kept at 0.5 L.plant(-1).day(-1). N could be increased to 130 mg.plant(-1).day(-1) with an increase in water uptake. Thus, this system of nutrient additions that can be easily regulated could increase productivity of tomato fruits by preventing excess vegetative growth, and simultaneously reduce the environmental impact of wastewater.