臭氧浓度升高条件下大豆光合能力变化及光响应曲线的拟合模型比较

Comparison of Photosynthetic Capacity and Light Response Curve Models of Soybean Under Elevated Ozone Concentration

为研究臭氧(O_(3))浓度升高条件下大豆叶片光合能力、光响应曲线的变化以及光响应曲线拟合模型的适用性,以铁丰29为试验材料,于开顶式气室(OTCs)内进行盆栽试验,设置3个O_(3)浓度(CK:45 nL·L^(-1),T1:80±10 nL·L^(-1),T2:120±10 nL·L^(-1))熏蒸大豆,测量气体交换参数,使用非直角双曲线模型(NRH)、直角双曲线模型(RH)、修正直角双曲线模型(MRH)以及指数模型(EM)4种光响应曲线拟合模型,计算光合参数,并分析比较4种光响应曲线模型的拟合效果。结果表明:O_(3)浓度升高显著降低了大豆叶片的最大净光合速率(P_(max))、表观量子效率(AQE)、气孔导度(Gs)、蒸腾速率(Tr)、胞间CO_(2)浓度(Ci)和水分利用效率(WUE),提高了光补偿点(LCP),光饱和点(LSP)无明显变化,高浓度O_(3)未对大豆叶片的强光利用能力以及暗呼吸速率(R_(d))产生影响。各模型下光响应参数拟合结果显示,修正的直角双曲线模型(MRH)拟合效果较好,但高浓度O_(3)条件下拟合光饱和点(LSP)时,MRH模型拟合效果较差,而指数模型(EM)拟合效果较好。综上所述,O_(3)浓度升高显著降低了大豆叶片的光合能力,在进行光响应曲线拟合时,选择MRH模型较好,其次为EM模型。

In order to study the changes of photosynthetic capacity and light response curve of soybean leaves and the applicability of light response curve fitting model under the condition of elevated ozone(O_(3)) concentration, a pot experiment was conducted in open top chambers(OTCs) with Tiefeng 29 as experimental material. Three O_(3) concentrations(CK: 45 nL·L^(-1), T_(1): 80±10 nL·L^(-1), T_(2): 120±10 nL·L^(-1)) were set to fumigate soybean, and the air pressure was measured. We used four light response curve fitting models including non right angle hyperbolic model(NRH), right angle hyperbolic model(RH), modified right angle hyperbolic model(MRH) and exponential model(EM) to calculate the photosynthetic parameters, furthermore analyzed and compared the fitting effects of the four light response curve models. The results showed that the maximum net photosynthetic rate(P_(max)), apparent quantum efficiency(AQE), stomatal conductance(Gs), transpiration rate(Tr), intercellular CO_(2) concentration(Ci) and water use efficiency(WUE) of soybean leaves were significantly decreased, and the light compensation point(LCP) and light saturation point(LSP) of soybean leaves were not significantly changed with the increase of O_(3) concentration. The ability of respiration and the rate of dark respiration(R_(d)) were affected. The fitting results of light response parameters under each model showed that the modified right angle hyperbolic model(MRH) had better fitting effect, but the fitting effect of MRH model was poor when fitting light saturation point(LSP) was under high O_(3) concentration, while the fitting effect of EM model was better. In conclusion, the increase of O_(3) concentration significantly reduced the photosynthetic capacity of soybean leaves. When fitting the light response curve, MRH model was better, followed by EM model.