The Response Of The Photosynthesis Characterristics Of Series Coniferous And Broadleaved Species To Soil Water Stress In Front Mountain Of Daqing

In this paper, determination and study on the variation of photosynthetic rate,Chlorophyll fluorescence characteristics in different soil water of Betula platyphylla suk.,Acer ginnala Maxim,Populus davidiana Dode.,Quercus wutaishanica Mayr.,Cotoneaster acutifolia Turcz's used Licor-6400 Portable photosynthesis system ,the result shows:(1) The days of the Chlorophyll fluorescence characteristics index began to decrease when the natural dehydration lagging behind the photosynthetic rate.(2) The effects of soil water content changes to net photosynthetic rate is very small when the soil water content is larger; When the soil water content dropped to a certain time, net photosynthetic rate began to drop, and the result show that the soil water content began to drop was basically the same in Stomatal conductance and net photosynthetic rate in test trees.(3) The effects of soil water content changes to Chlorophyll fluorescence characteristics index is very small when the soil water content is larger; When the soil water content dropped to a certain time, Chlorophyll fluorescence characteristics index began to drop. The result shows that the soil water content of NPQ and ETR began to drop was bigger the Fv/Fm began to drop soil water and smaller the net photosynthetic rate began to drop soil water.(4) According to the relationship between the photosynthetic rate and soil water content , We can be divided into three levels of soil water stress: Mild soil water stress,Moderate soil water stress and Serious soil water stress, and the soil water content of net photosynthetic rate began to drop,the soil water content of ETR began to drop and the soil water content of Fv/Fm began to drop was they critical point.(5) Through drought membership function method comprehensive evaluation the trees drought resistance, the adaptability of tress to drought descending order from big to small is Populus davidiana Dode(0.771)> Quercus wutaishanica Mayr(0.540)>Acer ginnala Maxim(0.340)> Betula platyphylla suk.(0.312)> Cotoneaster acutifolia Turcz(0.227)...