大气CO2浓度升高对茶树光合生理特性的影响

通过对不同大气CO2浓度水平下的茶树观测试验,研究了大气CO2增长对茶树新梢叶片净光合速率、蒸腾气孔导度、水分利用效率、叶绿素含量和营养元素含量等光合生理特性的影响。结果表明,在大气CO2浓度为550、750μmol·mol-1时,比正常大气CO2水平下茶树叶片日平均净光合速率提高17.9%和25.8%,并缓解和消除了光合午休现象;茶树叶片气孔导度降低7.6%和13.0%,蒸腾速度稍有下降,水分利用效率提高21.6%和35.8%;同时使茶树新梢叶绿素a、叶绿素b、叶绿素总量和类胡萝卜素含量分别提高12.8%～18.4%、14.0%～22.0%、13.1%～19.4%和17.2%～20.1%,但叶绿素a与叶绿素b的比值有所降低。大气CO2浓度的升高使新梢营养元素N、K、Ca含量有不同程度降低,而Mg、Fe、Zn、Mn、Cu含量有所增加。

Effects of Elevated Atmospheric CO2 Concentration on Photo-physiological Characteristics of Tea Plant

The net photosynthesis(Pn), transpiration(Tr), stomatal conductance(Sc), water use efficiency (WUE), chlorophyll contents and nutrient elements content of tea plant under ambient and elevated CO2 conditions were measured, and responses to elevated CO2 were discussed. The results showed that Pn increased by 17.9% and 25.8% under elevated (550 and 750μmol·mol-1)CO2, compared to the ambient air CO2 concentration. At the same time, midday depression of photosynthesis abated or disappeared. Sc reduced by 7.6% and 13.0% and Tr decreased slightly. WUE increased by 21.6% and 35.8%. It was also found that chlorophyll a, chlorophyll b, total chlorophyll and carotennoid contents increased by 12.8%～18.4%, 14.0%～22.0%, 13.1%～19.4% and 17.2%～20.1% in shoots of tea plant. However, the ratio of chlorophyll a to b reduced. The N, K, and Ca contents in shoots decreased to some extent. The Mg, Fe, Zn, Mn and Cu contents increased with CO2 enrichment.