| Budget Amount *help |
¥12,300,000 (Direct Cost: ¥12,300,000)
Fiscal Year 2001: ¥3,900,000 (Direct Cost: ¥3,900,000)
Fiscal Year 2000: ¥8,400,000 (Direct Cost: ¥8,400,000)
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| Research Abstract |
In this study, advanced environmental control techniques for cultivation and storage were developed to attain the qualitative improvements of tomato fruits.
1. Qualitative improvement of fruits during hydroponic cultivation
In the granular rockwool cultivation, water stress was applied to tomato plants by the irrigation control to improve the fruit quality, and various indexes for the irrigation control were examined. Especially, two indexes, (1) leaf temperature index defined as the ratio of the difference between non-evaporative surface temperature and evaporative surface temperature and the difference between non-evaporative surface temperature and leaf temperature and (2) index of the accumulated transpiration of tomato plant which is estimated from solar radiation and saturation deficit, were effective for obtaining high quality tomatoes characterizing with Brix of 8%.
2. Qualitative improvement of fruits during storage
The storability of two types of harvested tomatoes, grown in wate
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r stress and non-water stress conditions, were investigated. An optimal temperature operation to minimize the water loss rate and respiration rate of the fruits during storage was explored using intelligent control techniques. The application of water stress to tomato plants during cultivation allowed the water loss of fruits during storage to be significantly reduced and provided a longer storability. Changes in the water loss rate, respiration rate and skin color, as affected by the temperature, were identified using neural networks. The optimal 6-step set points of temperatures that minimize the water loss rate and respiration rate were sought through simulations of the models using genetic algorithms. A single heat stress T = {40, 15, 15, 15, 15, 15℃} was obtained as an optimal. A temperature operation first rising to the highest level and then dropping to the lowest level in the given range provided a lower rate of the water loss than by keeping constant at the lowest level through whole process.
Thus, it is assumed that the combination of the water stress application to the plants during cultivation and the heat stress application to the fruits during storage is useful for the production of high quality tomatoes. Less
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