不同氮素水平下二氧化碳加富对草莓叶片光抑制的影响

Effects of elevated CO_2 on photoinhibition of strawberry leaves under different nitrogen levels

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0.4mmol.L-1)和不同CO2浓度下(700和390μl.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,12mmol.L-1供氮水平的草莓叶片净光合速率升高了62.7%,4和0.4mmol.L-1供氮水平则分别降低了7.4%和21.3%;12mmol.L-1供氮水平的Fm和Fv/Fm在强光胁迫时降辐减小,暗恢复时Fm和Fv/Fm恢复程度提高,而4和0.4mmol.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.

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 QB-non-reducing PSⅡ reaction centers [ （ Fi - Fo ） / （ Fp - Fo ） ] , and net photosynthetic rate （Pn） of strawberry leaves under conditions of elevated CO2 （700 μl2L^-1） and ambient CO2（390 μl·L^-1 ） at three levels of nitrogen application （ 12, 4 and 0. 4 mmol·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 P. in treatment 12 mmol N·L^-1 increased by 62.7%, while that in treatments 4 and 0. 4 mmol N· 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 ·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 ·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.