| Through monitoring simultaneously three physiological indexes(stem flux rate, trunk or stem diameter variations, leaf temperature)of several kinds of plants growing in Xinjiang Karamay Agricultural Comprehensive Development Region, four of which are introduced plants, that is, Fraxinus szaboana, Populus alba×P.alba var. pyramidalis, Populus russkii, Ulmus pumila, two of which are cultivated indigenous plants, that is Tamarix ramosissima, Populus euphratica, four of which are natural desert plants, that is Tamarix leptostachys, Haloxylon persicum, Tamarix ramosissima, Haloxylon ammodendron, and the environmental factors (air temperature, air relative humidity, solar radiation, soil moisture, wind speed) using a Phytalk phytomonitor system which was produced by PhyTech Company in Israel, this thesis systematically analyzes the correlation between them and establishs the mathematics reaction model of the three indexes to environmental factors by stepwise regression analysis. The results are as follows:Change trends of the day process of the stem flux of these plants are approximately same, showing remarkable day and night rhythms, while this fluctuation in day is more evident than in night. Taking Fraxinus szaboana as an example, the extent of the stem flux rate is changeable under different weather conditions. In sunny day, the stem flux rate presents single-peak curve and the day and night variation is evident, the maximum occurs around 15:00 p.m. and the peak is 0.422 mL/h. In cloudy day the stem flux rate appears two-peak curve with peak value 0.333 mL/h and 0.317 mL/h respectively, which occurs around 9:00 a.m. and 12:00 a.m.. But the changes are unsteady in cloudy day and overcast day. According to the day dynamic of the stem flux rate in sunny day, it concludes that these plants, except Ulmus pumila, ascends when solar radiation changes strong, air temperature rise, vapor pressure deficit augments, air relative humidity descends and it reaches peak when these factors reaches peak. In addition, the stem flux rate of these natural desert plants presents obvious"stem flux noon break"at noon and holds high and steady value at night. By stepwise regression analysis, it indicates that the main environmental factors affecting the stem flux rate of these plants are solar total radiation, air temperature, soil moisture, vapor pressure deficit and wind speed, in which the solar radiation is the first.Through analysis on the stem diameter variations of these plants except Haloxylon ammodendron, the results are as follows: The day process of the stem diameter variations has obvious day and night variation law, which shows that there is shrinking in the day and swelling in the night. But the apex value time and valley value time of stem diameter variations of different species reach differently. Taking Fraxinus szaboana as an example, the extent of the stem maximum shrinkage of the stem diameter in sunny day is evidently bigger than that in cloudy day and overcast day. In sunny day, the maximum shrinkage of trunk, leader branch and side branch is -0.17mm, -58um and -88um respectively, while in overcast day is -0.043mm, -29um and -34um. And the extent of the stem diameter variations in cloudy weather comes between the sunny day and the overcast day. Through comparison of the stem diameter variation trends of leader branch and side branch and correlation analysis between them of the same plant, it indicates that the stem diameter variations on different parts of the same plant have the same trend, but the variation extent is different. Both correlation analysis and regression analysis show that the trunk diameter variations are mainly affected by factors of air temperature, soil moisture, vapor pressure deficit, solar radiation and wind speed. Leader branch diameter variations are mainly affected by air temperature, vapor pressure deficit, soil moisture and solar radiation, while side branch diameter variations are mainly affected by air temperature, soil moisture, air relative humidity and vapor pressure deficit.Through analysis on the dynamic variations of the leaf temperature, it indicates that the leaf temperature of these plants keeps with that of air temperature, and air temperature is slightly higher at day but leaf temperature slightly higher on a certain period at night. Taking Fraxinus szaboana as an example, under different weather conditions the difference between leaf temperature and air temperature is obvious in sunny day, smaller at morning and night, larger at noon, and fluctuating near zero in cloudy day and overcast day. The results of regression analysis show that air temperature is the prime and vital factor on influencing leaf temperature.
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