不同氮素水平下二氧化碳加富对草莓叶片光抑制的影响

用便携式调制叶绿素荧光仪和光合仪研究了强光下不同供氮水平（12、4和0.4 mmol·L^-1）和不同CO₂浓度下（700和390 μl·L^-1）丰香草莓叶片的荧光参数及净光合速率的变化.结果表明，CO₂和氮素对草莓叶片光抑制有明显的互作效应.在富CO₂下，12 mmol·L^-1供氮水平的草莓叶片净光合速率升高了62.7%，4和0.4 mmol·L^-1供氮水平则分别降低了7.4%和21.3%；12 mmol·L^-1供氮水平的F_m和F_v/F_m在强光胁迫时降辐减小，暗恢复时F_m和F_v/F_m恢复程度提高，而4和0.4 mmol·L^-1供氮水平却相反.表明氮素供应不足时草莓叶片在富CO₂环境下光合作用出现适应性下调，光抑制增强.

Effects of elevated CO2 on photoinhibition of strawberry leaves under different nitrogen levels

By using PAM-2000 portable chlorophyll fluorometer and HCM-1000 photosynthesis measurement system, this paper measured the initial fluorescence (Fo), maximal photochemical efficiency of PSII (Fv/Fm), maximal fluorescence (Fm), amount of inactive PS II reaction centers (Fi-Fo), proportion of Q(B)-non-reducing PS II reaction centers (Fi-Fo)/(Fp-Fo)], and net photosynthetic rate (Pn) of strawberry leaves under conditions of elevated CO2 (700 microl x L(-1)) and ambient CO2 (390 microl x L(-1)) at three levels of nitrogen application (12, 4 and 0.4 mmol x L(-1)). The results showed that there was a significant joint effect between CO2 and N on the photoinhibition of strawberry leaves. Under elevated CO2 condition, the Pn in treatment 12 mmol N x L(-1) increased by 62.7%, while that in treatments 4 and 0.4 mmol N x L(-1) decreased by 7.4% and 21.3%, respectively. When exposed to high light and subsequently recovered in dark for 4 hours, the strawberry leaves in treatment 12 mmol N x L(-1) showed less changes of Fm and Fv/Fm in elevated CO2 than in ambient CO2, while those in treatments 4 and 0.4 mmol N x L(-1) were in adverse, suggesting that for the strawberry leaves in elevated CO2, nitrogen deficiency could result in an acclimatized decrease of photosynthesis and an increase of photoinhibition.