Effect of continuous and intermittent solution circulation on tomato plants grown in NFT

This experiment was carried out during the autumn in 1998 and spring in 1999. Three different tomato varieties were grown in NFT systems in which nutrient solution was circulated continuously or intermittently. The intermittent flow system was controlled by a timer set for 45 minutes flowing and 15 minutes off. In autumn, harvest season extended for 4 months. Intermittent flow increased cumulative yields compared to continuous flow by 106.8, 50.7 and 14.2 % in the first 3 months of picking in order. However, there was no significant difference between continuous and intermittent circulation in respect to total yield. In spring, solution circulation regime did not affect neither the early nor the total yield. Although there were no significant differences between intermittent and continuous flow in fruit quality characteristics in autumn, intermittent flow resulted in a marked increase in the EC of fruit juice and decrease in dry matter and vitamin C content in spring. In both seasons, significant differences were found between varieties with respect to some parameters, but the interactions between circulation regime and variety were not significant.