基于FvCB模型估算小麦的最大电子传递速率

Estimation of Maximum Electron Transport Rate of Wheat Based on FvCB Model

在Farquhar、von Caemermer和Berry模型(以下简称FvCB生化模型)中有2个子模型,即非直角双曲线模型和核酮糖-1,5-双磷酸(RuBP)再生速率限制模型,用其可以估算C3植物叶片的最大电子传递速率(Jmax)。为了严格验证由这2个子模型估算植物叶片Jmax的精确度,本研究用LI-6400-40光合测定仪分别测定了2%和21%O2浓度下小麦(Triticum aestivum L.)叶片的光合速率和电子传递速率对光和CO2的响应曲线,并用此2个模型分别拟合了21%O2浓度下小麦光合速率对CO2的响应曲线和电子传递速率对光的响应曲线。结果表明,由非直角双曲线模型拟合小麦电子传递速率对光的响应曲线得到的Jmax为254.86μmol·m^-2·s^-1,显著高于其观测值(236.37μmol·m^-2·s^-1)(P<0.05);由RuBP再生速率限制子模型拟合小麦光合速率对CO2的响应曲线得到的Jmax为260.58μmol·m^-2·s^-1,则显著低于其观测值(298.05μmol·m^-2·s^-1)(P<0.05)。此外,当胞间CO2浓度(Ci)为738.01μmol·mol-1时,小麦处于RuBP再生速率限制阶段,此时其净光合速率及其相应的光呼吸速率分别为61.16和8.55μmol·m^-2·s^-1。在不考虑其他路径消耗光合电子的情况下,小麦在该Ci时同化这些碳至少需要光合电子流为352.24μmol·m^-2·s^-1,这与由RuBP再生速率限制子模型估算的Jmax(260.58μmol·m^-2·s^-1)之间存在显著差异(P<0.05)。这说明非直角双曲线模型和RuBP再生速率限制子模型在估算小麦叶片Jmax上存在缺陷,有待改进。

Both the non-rectangular hyperbolic model and ribulose-1,5-disphosphate(RuBP)regeneration limitation model are the two main sub-models of the FvCB model,which are used to estimate the maximum electron transport rate(Jmax)of wheat(Triticum aestivum).The two sub-models have been widely applied to fit the light-response curves of electron transport rate(J-I curves)and CO2-response curves of photosynthesis,and obtain Jmax.However,it has not been strictly verified whether Jmaxcalculated by the two models are consistent with the observed values.Light-response curves of electron transport rate and CO2-response curves of photosynthesis of wheat under 2%and 21%O2concentrations were simultaneously measured by LI-6400-40,and these data of 21%O2concentration were simulated by the two models.The results showed that the Jmaxestimated by non-rectangular model was 254.86μmol·m^-2·s^-1,and the observation was 236.37μmol·m^-2·s^-1,and the Jmaxestimated by RuBP regeneration limitation model was 260.58μmol·m^-2·s^-1,and the observation was 298.05μmol·m^-2·s^-1.There were significant differences between Jmaxestimated by the two models and the corresponding observation data(P<0.05).Moreover,wheat was under RuBP regeneration limitation while Ciequaled to 738.01μmol·mol-1,and its net photosynthetic rate was 61.16μmol·m^-2·s^-1 and its photoresporatory rate was 8.55μmol·m^-2·s^-1.When other pathway of consumption photosynthetic electron was neglected,the minimum photosynthetic electrons should be 352.24μmol·m^-2·s^-1,which was larger than that of 260.58μmol·m^-2·s^-1 estimated by the RuBP regeneration limitation model.Therefore,it can be concluded that Jmaxestimated by non-rectangular hyperbolic model and RuBP regeneration limitation model did not meet the photosynthetic electrons needed for carbon assimilation,which need to be further improved.