| The modern greenhouse provide the possibility of suitable climatecondition for plant growing., but the optimum control of environmental parameters is still the problem because it varies depend on the various plant species, various growth periods, various section for whole day so it is very complex to set up a expert system for optimal control of environment. Based on the water potential, the thesis try to search some simple approaches to get the relationship between the adaptability of plant and environmental parameters.This experiment was carried out from 2002 to 2003 under NFT system, DFT system and substrate culture in the east-China type multi-span plastic greenhouse and artificial climate chamber, which located in the Institute of Agriculture Bio-environment, Zhejiang University. On the basis of analysis some physiological indices such as the leaf water potential, the adaptability of soilless cherry tomato to adversity environment was evaluated and the key technological system was studied systematically. The main results are as follows:(1) The growth and some relative physiological characteristics of cherry tomato in the phytotron NFT were compared with ones of cherry tomato grown in soil (control). The results showed that several physiological indices were improved, including the higher leaf water potential and the higher succinic dehydrogenase activity in the root tissue. The plant growth was also enhanced, e.g. the higher fruit yield, the higher plant and more leaves.(2) The diurnal variation of leaf water potential of cherry tomato seedling in NFT was compared with those in soil. The correlation of leaf water potential with the environmental factors was also studied. The resultsshowed that during a sunny day, the diurnal variation of leaf water potential of tomato seedling in soil was greater than those in NFT. The change pattern was that the leaf water potential increased with the increasing of air humidity and decreased with the increasing of light intensity and air temperature. In view of leaf water potential, the tomato plants in NFT had better adaptability to environment variation than the plants in soil.(3) The influence of high temperature stress on several physiological indices of cherry tomato in NFT and in soil was studied in this paper. The variation of physiological indices, including leaf water potential, photosynthetic rate and superoxidey dismutase of cherry tomato under high temperature stress was measured. The results showed that the physiological indices mentioned above decreased dramatically when the plants were planted in soil under high temperature condition, while only a slight decreas was found from the plants planted in NFT. It can be concluded that the heat resistance of tomato seedling under NFT was stronger than that under soil culture.(4) The variations of some physiological indices of cherry tomato at fruiting stage in DFT and in soil were examined in response to low light intensity created by shading in the east-China type multi-span plastic greenhouse. The results showed that leaf water potential, net photosynthetic rate and root activity of cherry tomato in soil were decreased significantly, while those indices of cherry tomato in DFT was slightly affected. So it can be concluded that the adaptability of cherry tomato in DFT was better than that in soil.(5) The effects of different intermission irrigation in NFT on the leaf water potential of cherry tomato at all growth stages were studied. The correlation of leaf water potential with the environmental factors was also discussed. The results showed that the leaf water potential decreased with the development of cherry tomato. In the three treatments, the longer the intermittence time was, the more the leaf water potential decreased. We found that the best one was the treatment with 20-minute intermittence timeand 15-second irrigation time, since it not only saved energy, but also it enabled tomato to maintain high leave water potential. It was clear that environment factors had great influe...
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