| The main purpose of this paper is to study the growth of cucumber by measuring the physiological indicators facilities (leaf water potential and transpiration rate, Photosynthesis, stomatal conductance, leaf temperature, photo synthetically active radiation (PAR)) and weather information on the environment (soil water content, temperature, relative humidity), focusing on the study of the relationship between leaf water potential and soil water potential, analyzed the relationship between leaf water potential and other physiological indicators of the environment and weather information. In addition, in the plant incubator, author set temperature, humidity, Light set in several different values of a fixed group, to measure the leaf water potential and soil water potential, to analyze the relationship between the leaf water potential and soil water relationship.According to the experimental program, analysis of data, the author has the following results. In this article, t is the representative of time,ΨS is the representative of leaf water potential, andΨL is the representative of soil water potential.(1) The cucumber′s leaf water potential of the morning is higher, with the rising in temperature, increasing the intensity of radiation, relative humidity, the leaf water potential dropped. In the noon 11:30~15:00, leaf water of cucumber is the lowest; with the increasing of the temperature, radiation intensity, relative humidity, the leaf water potential start to move up. Significantly increasing interval of the leaf water potential is the range between 6:00 in the morning to 14:30, the rest in the fall interval. Because of gradual drought in this experiment, when gradually increase in the degree of drought, leaf water potential on the one day have the roughly similar trend., but with the extent of the drought increased, the daily value of the starting leaf water potential to reduce, and it have the overall downward trend;(2) The author from July 17, 2006 to July 24, 2006, in accordance with the method described in this paper for tracking test in a row. With the soil drying, using statistical methods of curve fitting to analyze the leaf water potential of the moment and extent of changes in the data , the conclusions are shown in table 1;(3) The author did not exhaustively analyze the diurnal variation of soil water potential, only analyzed the conditions without water every day for one week within the same time all the data of soil water potential changes, as a representative to spell out changes in soil water distribution rules. From July 17, 2006 to July 24, 2006, under the conditions without water every day for one week within the same time, the author has the change′s relationship of the soil water potential, that relationship is linear model, the linear model as follows:(4) Taking the method of gray correlation analysis, Analyzed correlation ranking between cucumber′s leaf water potential and physiological indicators of relative humidity and transpiration rate, net photosynthesis rate, stomatal conductance, leaf temperature, PAR, According correlation ranking, which affects greenhouse cucumber leaf water potential factors, the author has the sequence of the photosynthetic rate, air relative humidity, transpiration, stomatal conductance, PAR, leaf temperature and air temperature, the correlation ranking are as follows:0.77904, 0.73899, 0.58771, 0.52774, 0.50956, 0.50731 and 0.49887;(5) In this paper the author set up the GM (1, 8) dynamic model between the greenhouse cucumber leaf water potential and the greenhouse temperature, relative humidity, transpiration, photosynthesis rate, stomatal conductance, leaf temperature, PAR. GM (1, 8) dynamic model was as follows:after testing, the model have the required precision;(6) The author from July 17, 2006 to July 24, 2006, in accordance with the method described in the paper for tracking test in a row. With increasing of the soil drought, analyzed the data of every moment of the leaf water potential and soil water potential by curve fitting using mathematical statistics methods for the analysis, the conclusion is shown in Table 2; Table 2 Every time the relationship between leaf water potential and soil water potential with increasing of soil drought TIME MODEL EQUATION 8:30 10:30 12:30 14:30 16:30 Cubic Quadratic Quadratic Linear Linear 3S2ψL =?0 .702+4.525ψS+7.812ψS+4.494ψ2ψL = ?0 .433+2.546ψS+0.873ψS 2ψL = ?0 .709+2.629ψS+1.122ψSψL = ?1. 773+0.456ψSψL = ?1. 125+0.703ψS(7) From August 1, 2006 to August 2, 2006, under the circumstance of drought, measured leaf water potential and soil water potential, then use SPSS software to data process, the author has the relationship between leaf water potential and soil water potential, that relationship is the linear model, the linear model as follows:ψL = ?0. 578+01.301ψS(8) In the plant incubator, the first group is set up appropriately for the growth of cucumber; the second group is set up for the unfavorable conditions to the growth of cucumber, we can see in two different boxes installed, the leaf water potential have roughly similar trend, the overall downward trend, and growth of cucumber under adverse conditions, the data of the leaf water potential was obvious small, in particular, soil moisture is adequate in the case, the difference ismore obvious, but when the soil moisture deficit, the difference decreases, that situation illustrate that, when adequate soil moisture, mainly as a result of changes in leaf water potential is environmental impacts, when soil moisture deficit, as a result of changes in leaf water potential is the soil water potential, therefore, the main purpose of this paper is necessary and meaningful. By 6-2, in the plant incubator we can see in two different boxes installed, there have the soil water potential trend, the overall downward trend;(9) From August 10, 2006 to 10 September 2006, under no water, measured the leaf water potential and soil water potential, used SPSS software for data processing, The results are as follows, using quadratic model : 2ψL = ?1 .740?1.964ψS?1.718ψS,ψL = ?1 .432+0.406ψS?0.103ψS2 to express the relationship between the leaf water potential and soil water potential are very good, under the first group and second group set-up in the plant incubator; The study of the plant leaf water potential, in particular, the study of the relationship between the leaf water potential and soil water potential, the relationship between the leaf water potential and other environmental factors, to guide reasonable crop irrigation for farmland water balance calculation of the production of important guiding significance, moreover, in the study of soil-plant-atmosphere circulation of water movement, its relationship and so on, can make important academic significance. Thus they lay a solid theoretical base foundation for we can use plant own physiological indicators for the determination of their own water deficit, as well as water-saving irrigation facilities, in addition, to provide theoretical basis for the promotion of greenhouse automation and intelligent development. What direction for the future is the using of electronic technology and computer to control for automatic monitoring of environmental factors, and take automatic management for crop growth.
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