Abstract
Tomato plants were pruned and trained to a single-truss cropping system and grown hydroponically in a greenhouse kept at minimum air temperatures of 5°C, 10°C, 15°C, and 20°C. The yield and fruit quality were studied. When flower buds attained the size of rice garains, tomato seedlings were transplanted, and treatment began. Higher minimum air temperatures advanced maturity, considerably shortened the length of cultivation, but decreased the average weight of the fruit. Minimum air temperature had a greater affect on reducing the cultivation period than it had on decreasing fruit yield. Fruit growth rate was not increaesd significantly at higher minimum air temperature. We postulate that at higher air temperatures, the fruit became mature before sufficient fruit growth occurred. Hence, the fruits were smaller at harvest. The Brix of fruit was affected little by minimum air temperature, but the titratable acidity of the fruit juice was significantly increased by high minimum air temperatures.
