Research about global sustainable soilless curture in the open field conditions using small-planet greenhouse

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This research project was carried out from 1998 to 2000 for the purpose of developing simplified soilless culture systems and growing softwares adapted to a wide range of clim atic and geographical conditions, and sustainable agriculture such as saving fertilizer and water. At that time, full open-roof greenhouses (Cabrio type) were built for controlling several environmental conditions with micro-computers. At first, we investigated the distribution of temperature and solar radiation, and effect of a shade-curtain on high temperature control in these greenhouses. As a result, temperature was almost uniform, but solar radiation varied widely inside the greenhouse, and the shade-curtain enhanced temperature build-up. Also we investigated the physico-chemical properties of several substrates. Results indicated that these organic substrates could replace rockwool. As a preliminary examination, we investigated the effect of substrate volume, and composition on the growth and yield of tomato grown in the open field. Tomato and lettuce were grown on simylated tropical conditions, and established a growing systems using indigenous substrates. From these results, we experimated the nutrients control system based on integrated solar radiation, and recognized that the system is environment-friendly.Through these researches, it is necesary to make further investigation on the absorption of water and fertilizer with respect to plant's growth stage and environmental conditions.