Control of nutrient solution supply to tomato plants grown in a soilless culture system suitable for use on sloping land.

摘要

The effects of installing a soilless culture system and a sloped greenhouse on tomato production in a hillside field were studied. Between 2002 and 2005, we compared tomato cultivation using a sloped greenhouse and a soilless culture system with the conventional rain shelter cultivation. The greenhouse was built on a ground with a slope of 4-20 degrees , approximately 300-360 m above sea level. The higher temperatures in the sloped greenhouse during the early spring and autumn allowed earlier planting, and longer harvesting season and cycle compared to the conventional rain shelter. Tomato (cultivars Momotaro 8 and Momotaro Fight) were transplanted from the end of April to the beginning of May in the sloped greenhouse, and from the end of May to the beginning of June under the conventional rain shelters. Tomato yields in the sloped greenhouse with the soilless culture system were much higher, due to the longer cycle, than those obtained in the conventional rain shelters. We also investigated a reasonable substrate and method for controlling the nutrient solution supply to tomato plants grown in the soilless culture system. Two kinds of bark and rockwool were used as substrates of the system. There were no significant differences in the yields in each substrate. We compared two methods of controlling the supply of nutrient solution. In one method, solution was supplied whenever the cumulated solar radiation reached a set point. For the other method, the solution supply was controlled during a 24-h time switch. Fruits yields were also the same between the two methods of controlling the supply.