| With the rapid development of our country's economy and the improvement of people's living standard, the demand for high quality, non-pollution and nutrient farm produce is becoming stronger. Agricultural Department of Chinese has planned "Action of Non-pollution'\ "Project of Three-green" to raise quality of farm produce and ensure security of farm produce consumption. Soilless cultivation that has acted as an important means of producing green vegetable and anti-seasonal vegetable had been applied to wide areas, and that technique had been improved rapidly, and showed wider foreground.As a close soilless cultivation system, the Nutrient Film Technique (NFT) cultivation is an economic and effective technique. In this system, the nutrient solution can be used circularly, so that plants can absorb fertilizer and water efficiently. Plant roots partly immerge in the nutrient solution, which not only ensure the demand for water and nutrition adequately, but also resolve the problem of oxygen supply for root system. However, it brings new problems that too long intermittent time may affect plant growth and even result in vegetable losing water seriously because of no water supply for a long time. Otherwise, the cost of the system would be increased with too short intermittent time due to over much electricity consumption, which may affect the technique popularization. The different intermittent time under the NFT cultivation means different irrigation in a day, and it can affect water content of plant and biological indices of plant. Leaf water potential is an important index of reflecting the water situation of whole plant, so we use leaf water potential as signs of water situation of cherry tomato.Therefore, four treatment methods were adopted in this experiment. The design of experiment was as follows: treatment one was providing water for fifteen seconds every ten minutes. Treatment two was providing water for fifteen seconds every twenty minutes. Treatment three was providing water for fifteen seconds every thirty minutes. As control experiment, treatment four was the Deep Flow Technique, which was supplying water once every twenty minutes. We measured leaf water potential of cherry tomato in different growing stages by use of WESCOR type of water potential instrument, and biological indices of cherry tomato in different growing stages. We expected that the method not only can maintain higher leaf water potential of cherry tomato, but also can save energy and water, which provided the theoretical basis for water-saving irrigation of agricultural production.The experiment results showed:(1) Leaf water potential varied with different growing stages under the NFT cultivation. Leaf water potential in the morning reflects the ability that the roots of plant absorb water. The trend was that leaf water potential in the morning reached the highest level in seedling stages, and decreased in anthesis and ripening stages. The midday leaf water potential in seedling stages was higher than that of anthesis. But in ripening stages it was lower than that of seedling stages, and higher than that of anthesis.(2) The diurnal change of leaf water potential was seriously affected by environmental factors. It increased with increasing of air humidity, and decreased with increasing of illumination and air temperature. The response degree to environment increased with prolonging of the intermittent time.(3) Different treatments had influenced leaf water potential differently under the NFT cultivation. The diurnal change of leaf water potential of treatment one was the smallest, and leaf water potential reached the highest level. While the diurnal change of leaf water potential of treatment three was the largest, and leaf water potential was the lowest level. The treatment two not only maintains the higher water potential, but also save water and energy. So the treatment two can be applied to larger areas in agriculture.(4) The correlation between leaf water potential and environmental factors had...
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