The Effect of Daily Nutrient Applications on Yield, Fruit Quality, and Nutrient Uptake of Hydroponically Cultivated Tomato

Abstract

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.

Growth and Yield of Tomato Plants as Influenced by Nutrient Application Rates with Quantitative Control in Closed Rockwool Cultivation

“…Treatments consisted of two levels of EC control (high and low EC) in an open system and three levels of the quantitative control in a closed system, in which the daily supply was based on multiples of the standard quantity criterion for the DFT method (Nakano et al, 2006): 1.0 ×, 1.25 ×, and 1.5 ×. Irrigation was supplied according to the standard practices for local commercial soilless cultivation.…”

“…In the quantitative control, three solution concentrations were adapted from the one used in our previous study (Nakano et al, 2006) for each development stage. In all treatments, microelements (Otsuka House No.…”

“…The stock solution was added to the recycling irrigation water via electromagnetic metering pumps (EK type, Iwaki Co., Ltd., Tokyo, Japan) between 06:30 and 07:00 every morning. The quantity of nutrients was determined according to the quantity criteria developed in the DFT study (Nakano et al, 2006), which were determined from the average amount of water absorbed daily during the previous three days (i.e., a three-day running average). In the 1.0 × treatment, when the amount of water absorbed reached 0.2 L/plant, all nutrients (as stock solutions) equivalent to 42 mg N were supplied, and this changed to 14 mg N equivalent per 0.2 L between 0.4 and 1.0 L/plant and per 0.3 L between 1.0 and 1.6 L/plant.…”

“…In our new approach, nutrients are supplied to the plants daily, with the quantity based on the average amount of water absorbed during the previous three days. This index was previously shown to be reliable for predicting the nutrient requirements of plants (Nakano et al, 2006).…”

“…Hosoi and Hosono (2005) used the leaf area of plants as an index, but sampling the leaf area was destructive and impractically timeconsuming. To test a different approach, we used the amount of water absorbed per three-day period as an index that allowed the estimation of plant nutrient demand (Nakano et al, 2006). In this approach, tomato plants grown under the DFT system received a daily supply of all nutrients every morning, and the supplied solution recirculated all day.…”