气候变化对不同水分条件下柿幼树光合作用的影响

以两年生柿树为试材，研究了高浓度CO₂处理（700 μmol·mol^-1）、高温处理（日平均温度高于正常日平均温度约5 ℃）、高温和高浓度CO₂复合处理及对照（温度为外界环境温度，CO₂浓度380 μmol·mol^-1）对不同水分条件下柿树净光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、水分利用效率(WUE)、叶绿素含量和叶绿素荧光参数F_v/F_m、F_v/F_o的影响.结果表明:高温和高浓度CO₂复合处理使处于各水分条件下的柿树T_r、G_s减小，WUE增大；在高、中水分条件(分别为田间持水量的75%～85%和55%～65%)下高温和高浓度CO₂复合处理使柿树P_n增大，在低水分条件(为田间持水量的35%～45%)下使柿树P_n减小.高浓度CO₂处理使处于各水分条件下的柿树P_n、WUE增大，G_s、T减小.高温及高温和高浓度CO₂复合处理下WUE均受土壤水分状况的影响，并随土壤含水量的升高而升高.与对照相比，高浓度CO₂处理还提高了各水分条件下植株叶片水平的水分利用效率、叶绿素a、叶绿素b、叶绿素（a+b）、类胡萝卜素含量及F_v/F_m和F_v/F_o，缓解了水分胁迫，提高了柿树的抗逆能力.

Effects of climate change on photosynthesis of Diospyros kaki under different soil moisture conditions

Taking two-year-old Diospyros kaki as test material,this paper studied the effects of high stomatal conductance(G_s),water use efficiency(WUE),chlorophyll content, F_v/F_m,and F_v/F_o under different soil moisture conditions, with the ambient air temperature and CO_2 concentration(380 μmol·mol~(-1))as the conT_rol. Under all test soil moisture conditions, the combination of high CO_2 concentration and high temperature decreased the T_r and G_s, but increased the WUE. This combination increased the P_n when the soil moisture content was 75%-85%and 55%-65%of field capacity, but decreased the P_n when the soil moisture content was 35%-45%.High CO_2 concentration increased the P_n and WUE but decreased the G_s and T_r under all test soil moisture conditions. The effects of high temperature and its combination with high CO_2 concentration on the WUE depended on soil moisture condition, with the WUE increased with increasing soil moisture content. Comparing with the control, high CO_2 concentration also increased the leaf Chla,Chlb,Chl(a+b), and Car concentrations and the F_v/F_m and F_v/F_o values, relieved the water stress, and increased the stress-resistance of D.kaki.