大豆叶片光呼吸对光强和CO_2浓度的响应

Response of photorespiration of Glycine max leaves to light intensity and CO_2 concentration

利用低氧法(2% O_2)研究了大豆叶片光呼吸速率(R_p)对光强和CO_2浓度的响应。结果表明:当光合有效辐射强度(PAR)小于600μmol·m^(-2)·s^(-1)时,大豆叶片的R_p随光强的升高而几乎直线增加;当PAR约为1200μmol·m^(-2)·s^(-1)时,R_p达到最大值(12.69·mol CO_2·m^(-2)·s^(-1)),随后R_p随PAR的升高呈下降趋势;构建的光呼吸速率与光强的方程式拟合结果表明,大豆叶片最大光呼吸速率为13.42·mol CO_2·m^(-2)·s^(-1),其对应的光强为1207.74·mol·m^(-2)·s^(-1),该拟合值与实际测量值极为吻合(P>0.05);当PAR一定(2000μmol·m^(-2)·s^(-1))时,随着CO_2浓度的增加(0~1200μmol·mol^(-1)),大豆叶片的R_p呈先升高后下降变化,在600μmol·mol^(-1)时达到最大值(9.97·mol CO_2·m^(-2)·s^(-1));构建的光呼吸速率与CO_2浓度的方程式拟合结果表明,大豆叶片最大光呼吸速率为10.21·mol CO_2·m^(-2)·s^(-1),其对应的外界CO_2浓度为625.74·mol·mol^(-1)。该拟合值也与实际测量值极为吻合(P"0.05)。本文所构建的方程式可较好地拟合光呼吸速率对不同光强和不同CO_2浓度的响应,这对定量研究光呼吸提供了强有力的手段。

The light and CO2responses of photorespiration rate （Rp） of soybean （Glycine max） leaves were studied under 2% and 21% O2. The results showed that Rp of soybean leaves increased almost linearly with increasing photosynthetically active radiation （PAR） when PAR was less than 600 μmol·m^-2·s^-1; Rp reached the maximum value of 12.69 μmol CO2·m^-2·s^-1 when PAR was about 1200 μmol·m^-2·s^-1, and then Rp decreased with increasing PAR. The function relationship between Rp and PAR was constructed. The fitted result showed that the maximum value of Rp （Ppmax） was 13.42 μmol CO2·m^-2·s^-1, and the light intensity corresponding to Ppmax was 1207.74 μmol·m^-2·s^-1. The fitted values were extremely in agreement with the measured values （P〈0.05）. As air CO2 concentration （Ca） （0-1200 μmol·mol-1） increased, Rp of soybean leaves increased firstly and then decreased. It reached a maximum value of 9.97 μmol CO2·m^-2·s^-1 when Ca was about 600 μmol·mol-1. The function relationship between Rp and Ca was also constructed. The fitted result showed that the Ppmax was 10.21 SymbolmA@mol CO2·m^-2·s^-1, and the Ca corresponding to the Ppmax was 625.74 μmol·mol-1. The fitted values also accorded with the measured values （P〈0.05）. Thus, it can be concluded that the constructed function relationships between Rp and PAR and between Rp andCa would provide a powerful means for the quantitative study of photorespiration of plant leaves.