2007 Volume 6 Issue 3 Pages 391-397
Tomatoes were grown in a greenhouse using a hydroponic system with an improved nutrient solution (NO3−N : NH4−N : P : K : Ca : Mg : SO4 = 7.0 : 0.2 : 2.1 : 5.6 : 2.9 : 1.0 : 1.1 me · L−1), which has higher K and lower NH4-N, Ca, Mg and SO4 levels than the Ootsuka-A formula (control). The study investigated the effects of the concentration of the solution within the medium and the volume and concentration of the exhaust solution, on the growth and yield of the tomatoes. Stem diameter at the seventh cluster and above were significantly larger and the yield and ratio of marketable fruits were higher in the improved nutrient solution plot. Fluctuations of NO3-N, Ca, Mg and SO4 levels in the solutions within the medium and in the exhaust was smaller with the improved nutrient solution than with the control. EC also was lower with the improved nutrient solution. There was no difference in P uptake, whereas uptake of K was higher with the improved nutrient solution during the entire season, and from the begining of harvest to pinching for NO3-N, Ca, Mg and SO4. Changes in the ratio of nutrient absorption per water consumption (n/w) were limited and the ratio of n/w to nutrient concentration was 1.0 to 1.2. It was shown that the formation and concentration of the improved nutrient solution matched the uptake ratio of the tomato plant within the conditions of the experiment.
