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为明确斑枯病对罗布麻光合生理特征的影响,并据此制定其斑枯病严重度分级标准,在田间条件下研究了斑枯病不同严重度罗布麻叶片的光合生理特征。结果表明:健康罗布麻叶片净光合速率为15.65μmol·m-2·s-1、气孔导度为0.283 mol·m-2·s-1、蒸腾速率为7.98 mmol·m-2·s-1、胞间CO2浓度为467μmol/mol,回归方程计算所得健康叶片的净光合速率与实测值接近。随着罗布麻斑枯病严重度增加,叶片净光合速率、气孔导度和蒸腾速率呈显著指数下降趋势,胞间CO2浓度呈上升趋势;严重度指标与净光合速率、气孔导度、蒸腾速率、胞间CO2浓度回归方程的决定系数从大到小依次为相对变色面积>相对病斑面积>病斑数,三者与净光合速率的决定系数依次为0.849、0.796和0.537。根据净光合损失率分别为0、0.1%~10%、10.1%~20%、20.1%~50%、50.1%~80%、80.1%~90%和90.1%~100%及其对应的相对病斑面积和相对变色面积,可将斑枯病严重度分为7级。
In order to clarify the effects of spot blight on the photosynthetic physiological characteristics of Apocynum venetum L., the grading criteria of the severity of spot blight were established. The photosynthetic characteristics of Apocynaceae leaves at different seasons were studied under field conditions. The results showed that the net photosynthetic rate of Apocynum venetum leaves was 15.65μmol · m-2 · s-1, stomatal conductance was 0.283 mol · m-2 · s-1 and the transpiration rate was 7.98 mmol · m-2 · s-1 , And the intercellular CO2 concentration was 467 μmol / mol. The net photosynthetic rate of healthy leaves calculated by regression equation was close to the measured value. The photosynthetic rate, stomatal conductance and transpiration rate of leaves showed a significant exponential declining trend with increasing sesamia severity, and the intercellular CO2 concentration showed an upward trend. Severity index and net photosynthetic rate, stomatal conductance, transpiration rate The decay coefficients of the regression equation of intercellular CO2 concentration were relative color change area> relative lesion area> lesion number, and the determination coefficients of net photosynthetic rate and chlorophyll a were 0.849,0.796 and 0.537 respectively. According to the net photosynthetic loss rates were 0, 0.1% ~ 10%, 10.1% ~ 20%, 20.1% ~ 50%, 50.1% ~ 80%, 80.1% ~ 90% and 90.1% ~ 100% Spot area and relative color change area, the severity of spot blight can be divided into seven levels.