Study on Characteristics of Gas Exchange and Influencing Factors of Water Use Efficiency of Three Latifoliate Trees
Lü Ai-xia~1, YANG Ji-hua~(1,*) , XIA Jiang-bao~1, ZHENG Zhao-liang~2, WANG Zhao-pin~2(1.Soil and Water Conservation Department of Forestry College, Shandong Agricultural University, Taian, Shandong 271018; 2.Forestry Bureau of Jinan City, Jinan, Shandong 250002)
Gas exchange parameters and water use efficiency of Pistacia chinensis Bunge,Kalopanax septemlobus Koidz and Rekoelreuteria paniculata Laxm were studied under different environmental factors in order to explore the effects of environmental factors on the water use efficiency. The results of diurnal changes were as follows: Photosynthetically active radiation and temperature were synchronous and presented as single-peak curves, while air relative humidity as "U" curve. Transpiration rates were single-peak curves both in dry and rainy season. Photosynthesis rate of Kalopanax septemlobus Koidz was a double-peak curve in dry season, and the rests were all single-peak curves. Water use efficiency were all single-peak curves in rainy season, but in dry season that of Pistacia chinensis Bunge was a single-peak curve and the rest were both double-peak curves. By means of stepping multi-regression analysis the four extremely remarkable and relevant factors were intercellular CO_2 concentration, atmosphere CO_2 concentration, air relative humidity and leaf temperature. The results of primary components suggested that the influencing factors of water use efficiency of Pistacia chinensis Bunge can be classified into two kinds that were temperature and stomatal conductance, while that of the rest can be classified into three kinds which were temperature, stomatal conductance and CO_2 concentration.