| This paper studied plant transpiration through regulating and controlling environmental factors in greenhouse. We expected to find optimum environment condition for decreasing "inefficient" transpiration and improving water use efficiency. These would provide a basis for water economized using of facilities agriculture. The main results are as following:1. On the basis of the stem heat balance principle to measure the plant transpiration, with the instruments to collect meteorological data in greenhouse, we studied the variational rules of tomato sap flow under different environmental treatments through shading and obturating environment.The results showed the trend of tomato sunny sap flow was invariable in the obturated greenhouse,but sap flow was obviously diminished.Besides illuminance,temperature and humidity were necessary environmental parameters to affect tomato sap flow in greenhouse. Under the treatment of changing illuminance artificially in the daytime, sap flow was gradually diminished following the illuminance reduced, they had similar rules. But the sap flow curve was lagged to the illuminance curve, and had a time delay. When the greenhouse became dark in the daytime, sap flow was gradually diminished, but sap flow value was far bigger than sap flow value at night. When the greenhouse was in the dark in the different time section, the diminished speed of tomato sap flow was different.2. Through pot experiment, air temperature and humidity at growth point of amaranth, and transpiration consumption were studied under different surface coverage degrees in greenhouse. The results showed, the air temperature and humidity increased as the coverage degree rose. During day and night, transpiration decreased as coverage degree increased. Meanwhile, stepwise regression analyses revealed significant correlation between transpiration rate, daytime transpiration consumption and meteorological parameters under different surface coverage degrees. The effects of different surface coverages on root-top ratio, chlorophyll content, transpiration consumption, dry matter accumulation and water use efficiency of potted amaranth were extremely significant. Except water use efficiency increasing with the coverage degree enhanced, others diminished with the coverage degree increased. Water use efficiency of 15/16 circle coverage is 1.45 times of the comparison treatment; transpiration consumptions of 15/16 circle coverage, 3/4 circle coverage, 1/2 circle coverage and non-circle coverage treatment were 32.65%, 54.64%, 63.36% and 69.98% of the comparison treatment, respectively. Transpiration was bated and water use efficiency was enhanced at the same time passing sealing the part of space.3. Wind speed is a key factor to affect plant growth and transpiration. Setting different wind speed of two vegetable (sweet pepper and amaranth), we studied the effects of wind on vegetable transpiration and growth through pot experiment in greenhouse. The results showed, difference among day transpiration of sweet pepper seedlings under different wind speed was small, with day transpiration generally increasing as wind speed rose. As sweet pepper grew up, potted day transpiration disparities at different wind speed increased, day transpiration at 0.8m·s-1 exceeded its at 1.2m·s-1, now potted day transpiration showed by: T2> T3> T1> CK. In the late experiment period, CK's exceeded its at 0.4m·s-1, presented as: T2> T3> CK> T1. But according to the curves of potted amaranth transpiration rate and day transpiration, the effects of wind on potted amaranth transpiration is not much, their patients are identical affected by different wind speed. In general, transpiration rate and daily transpiration at 1.0m·s-1 are maximum, followed by those of 0.4m·s-1 and 0.0m·s-1, and the least at 2.0m·s-1. By all above results, there are differences in the effects of wind speed treaments of two experiments on two vegetables transpiration. There are many reasons passing analysis, crop itself exists genetic differences; two experimental seasons were different, there were notable differences of temperature and humidity environment factors; Wind speed treatments diversity, especially maximal wind speed was different; and supplying wind time was various. These are all possible reasons to cause two experimental result differences. Stepwise regression analyses revealed significant correlation between transpiration and meteorological parameters under different wind speeds. The best wind speed for sweet pepper growth and transpiration in greenhouse was 0.8m·s-1, it was 1.0m·s-1 for amaranth. Potted sweet pepper yield and crop water productivity under the most high wind speed (1.2m·s-1) were minimum; likewise, potted amaranth dry matter weight and water use efficiency were minimum. It was obvious that excessive wind speed increased "inefficient" transpiration, and reduced crop yield.4. Setting water supply tension at 10hPa, 30hPa, 50hPa and 70hPa, we studied the effects of water supply tension on transpiration and fresh matter accumulation of potted tomato by using negative pressure pot device in greenhouse. The results showed that the negative pressure pot device can realize the accuracy control to substrate moisture content, the substrate moisture content of pot equipment are 88%, 76%, 63% and 57% respectively under water supply tension at 10hPa, 30hPa, 50hPa and 70hPa. Daily transpiration of potted tomato is different because of the different substrate moisture treatments. At the beginning, daily transpiration of potted tomato at 30hPa is maximum, the second is 10hPa, and the least is 50hPa. During Medium-late Stage of experiment, daily transpiration of potted tomato at 10hPa is the first. At the same time, stepwise regression analyses revealed significant correlation between daily transpiration and meteorological parameters under water supply tension. Based on the fresh matter accumulation curve of potted tomato, the differences among the fresh matter accumulation of potted tomato caused by substrate moisture treatments are very significant, its of the 30hPa tension is maximal, followed by 10hPa and 50hPa, it is minimum at 70hPa. The effects of water supply tension in greenhouse on transpiration rate and stomatal conductance of potted tomato are extremely significant, it is notable effect to photosynthetic rate, but the effects to chlorophyll content and intercellular CO2 are not significant. Meanwhile, the effects of water supply tension on yield, transpiration water consumption and crop water productivity are extremely significant. The transpiration water consumption at 10hPa water supply tension is maximal, its yield is minimum. Therefore, excessive substrate moisture content increased "inefficient" transpiration, and reduced crop water productivity.5. Setting double-coverage treatment to the pot, we may regulate temperature and humidity in the closed pot. Dehumidifying and cooling, at the same time trying to recycle transpiration water to the pot. we will stride inaugurated one-step in the economical utilization of facility agriculture water resources. According to the principle of temperature disparity for heat exchange on this chapter, we explored preliminarily experimental effect of dehumidification, cooling down and recycling transpiration water. Firstly, we made use of temperature difference between water and air to dehumidify, cool down and recycle transpiration water in small closed environment. During the experiment initial stage, the effect of dehumidifying and cooling was remarkable. Compared with the closed check pot, its temperature reduces 3℃or so and its relative humidity comes down 7% at 12:30; dehumidifying and cooling effect in other time is inferior to that at noon, but its temperature cools down averagely 2.4℃in the daytime, and its relative humidity reduces averagely 5%. But several days later, recycled transpiration water all aggregates in U-tube, ultimately full of the bottom of U-tube, it makes air flow can not complete circulation, the test was fail. Afterwards, based on soil-to-air temperature difference for heat exchange, by using air pump to recycle vapor, we designed device to dehumidify, cool down and recycle transpiration water in the closed pot microenvironment. During the experiment, dehumidifying and cooling effect is not obvious in night. Temperature is basically consistent between the closed check pot and the pot treated by soil-air heat exchange in night; compared with the closed check pot, its relative humidity decreases averagely 6.2%; in night without opening pump, relative humidity of the pot treated by soil-air heat exchange field- gas heat exchange handles is 5.6% lower than that of the check. In the daytime with pump operation, compared with the closed check pot, temperature goes down averagely 2.5℃and relative humidity reduces 10% or so. At noon, there is the most notable effect of dehumidifying and cooling, its temperature decreases 5℃relative to the check, the temperature difference is 1.5℃or so between in the treated pot microenvironment and in greenhouse; humidity reduces 15%. Condensed water for cooling recycles to the pot under the drive of high speed flow.
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