Abstract
Limited nutrient supply control of tomato grown in substrate culture using a double trough bed was investigated. Two experiments were conducted to determine the effect of a reduced amount of nutrient supply. Experiment 1. Treatment with 50 me NO3-N·plant−1·week−1 was considered in the cultivation and management of limited nutrient supply control. As a result, the yield till 4th truss was not significant compared with that under an EC-based control method. However on the 5th to 6th truss, the yield was decreased. At the late growth stage of 6th truss pinching of tomato, the results showed that 50 me NO3-N·plant−1·week−1 should be increased. Experiment 2. The influence of the amount of NO3-N applied at the 6th truss pinching tomato growth stage was investigated. In limited nutrient supply control, the blooming periods of the 2nd, 4th and 6th flower clusters were treated with increasing amounts of 50, 70, 90 me NO3-N·plant−1·week−1, respectively. Compared with that under an EC-based control, these treatments reduced the inorganic component rate by 33% (NO3-N), 56% (NH4-N), 53% (PO4-P), 41% (K), 22% (Ca) and 76% Mg, respectively. These results show that it is possible to apply limited nutrient control on tomatoes grown by substrate culture using a double trough bed, resulting in the reduction of the inorganic component, particularly NO3-N.
