土壤水分胁迫对茶树光合作用-光响应特性的影响

Effect of soil water stress on photosynthetic light response curve of tea plant(Camellia sinensis)

采用盆栽试验研究正常供水(土壤含水量为田间最大持水量的75%)、轻度水分胁迫(55%)、中度水分胁迫(35%)和重度水分胁迫(20%)条件下,茶树"铁观音"和"福鼎大白茶"2年生幼苗光合作用-光响应特性。结果表明:"铁观音"、"福鼎大白茶"光合作用-光响应曲线符合指数模型。在正常供水条件下,"铁观音"、"福鼎大白茶"的最大光合速率(Pnmax)分别为8.169μmol(CO2)·m-2·s-1、3.946μmol(CO2)·m-2·s-1,表观量子效率(AQY)分别为0.039μmol(CO2)·μmol-1、0.024μmol(CO2)·μmol-1,光饱和点(LSP)分别为973.07μmol·m-2·s-1、775.78μmol·m-2·s-1,光补偿点(LCP)分别为5.15μmol·m-2·s-1、6.49μmol·m-2·s-1,暗呼吸速率(Rd)分别为1.025μmol(CO2)·m-2·s-1、1.040μmol(CO2)·m-2·s-1。土壤水分胁迫使"铁观音"、"福鼎大白茶"Pnmax、AQY、LSP显著降低,而LCP及Rd提高。无论在正常供水还是在水分胁迫下,"铁观音"均表现出更高的光合活性,其Pn、Pnmax、LSP及AQY均比"福鼎大白茶"高,而Rd、LCP比"福鼎大白茶"低。表明生长在同一生境中的"铁观音"对光照、土壤水分的生态适应能力高于"福鼎大白茶"。

Two-year-old seedlings of tea plants（Camellia sinensis cv.Tieguanyin and C.sinensis cv.Fudingdabaicha） were cultivated in a pot experiment to investigate the photosynthetic parameters with light intensity of PAR 0～2 000 μmol·m^-2·s^-1 under four water stress treatments： 75%（normal water supply）,55%（slight water stress）,35%（mild water stress） and 20%（severe water stress） of soil field capacity.The results show that light response curves of net photosynthetic rate（Pn） in ＂Tieguanyin＂ and ＂Fudingdabaicha＂ tea plants follow an exponential equation model.Under normal water supply condition,＂Tieguanyin＂ and ＂Fudingdabaicha＂ maximum net photosynthetic rates（Pnmax） are 8.169 μmol（CO2）·m^-2·s^-1 and 3.946 μmol（CO2）·m^-2·s^-1;apparent quantum yields（AQY） are 0.039 μmol（CO2）·μmol^-1 and 0.024 μmol（CO2）·μmol^-1;light saturation points（LSP） are 973.07 μmol·m^-2·s^-1 and 775.78 μmol·m^-2·s^-1;light compensation points（LCP） are 5.15 μmol·m^-2·s^-1 and 6.49 μmol·m^-2·s^-1;and dark respiration rates（Rd） are 1.025 μmol（CO2）·m^-2·s^-1 and 1.040 μmol（CO2）·m^-2·s^-1 respectively.Under soil drought stress,Pnmax,AQY and LSP decrease while LCP and Rd increase.Compared with ＂Fudingdabaicha＂,＂Tieguanyin＂ presents higher Pn,Pnmax,LSP and AQY,but lower LCP and Rd;indicating that ＂Tieguanyin＂ has higher adaptation capacity to different soil water supply and light intensity than ＂Fudingdabaicha＂ under the same environmental conditions.