不同灌溉处理对铁观音茶树光合作用的影响

以田间栽培的2年生铁观音茶树为试验材料，应用叶绿素荧光诱导动力学技术，以不灌溉为对照，分析不同灌溉间隔时间处理［5 d（T₁）、10 d (T₂)、15 d (T₃)、20 d (T₄) 和25 d (T₅)］对铁观音茶树叶片光合作用的影响.结果表明: 随着灌溉间隔期的延长，2年生铁观音茶树叶片水势和叶绿素含量降低; 净光合速率(P_n)先上升后降低，在T₂下达到最大(15.55 μmol·m^-2·s^-1); 光系统Ⅱ(PSⅡ)的原初光能转化效率(F_v/F_m)、可变荧光衰减(ΔF_v)和可变荧光淬灭速率(ΔF_v/F_o)均在T₂下达到最大值,分别为0.844、342.5和4.03.初始荧光(F_o)随着灌溉间隔期的延长而降低，而对照的F_o则呈上升趋势，表明干旱可对茶树叶片PSⅡ造成损害.灌溉间隔期为10 d处理有利于茶树叶片光合电子的传递和CO₂的同化，提高茶树的光合作用效率.

Effects of different irrigation treatments on photosynthesis of Tieguanyin tea plants.

By using chlorophyll fluorescence kinetics technique, the effects of different irrigation intervals, i.e., 5 d (T₁), 10 d (T₂), 15 d (T₃), 20 d (T₄), and 25 d (T₅), on the photosynthesis of 2-year Tieguanyin tea plants were investigated in the field, with no irrigation as the control. The results showed that the leaf water potential and chlorophyll content decreased with increasing irrigation interval, while the net photosynthesis (P_n) increased first and decreased then, reaching its highest value (15.55 μmol·m^-2·s^-1) in treatment T₂. The ratio of the variable to maximal fluorescence (F_v/F_m), the variable fluorescence quenching (ΔF_v), and the variable fluorescence quenching rate (ΔF_v/F_o) all got the highest in treatment T₂, being 0.844, 342.5, and 4.03, respectively. The initial fluorescence (F_o) decreased with increasing irrigation interval, while a reverse changing trend of F_o was observed in the control, demonstrating that PSⅡ reaction center was damaged by drought stress. In conclusion, irrigating per 10 d was favorable to the photosynthetic electron transport and CO₂ assimilation of the tea plants, which would enhance their photosynthesis efficiency.