烤烟不同部位叶片的光合特性研究

为明确烤烟不同部位叶片生长发育及品质差异形成的光合生理机制，以‘豫烟10号’为材料，在旺长期烟株现蕾时测定不同部位叶片光合特性及环境因子日变化进程，并采用通径分析法分析各环境因子对其净光合速率（Pn）的直接和间接影响。结果表明：（1）在现蕾期，‘豫烟10号’不同部位叶片Pn日变化均为“单峰型”，上、中、下部叶Pn日均值分别为13．25、11．7l、6．26μmolCO2／（m^2·s），下部叶鼢显著低于上、中部叶。（2）气孔导度（Gs）对烤烟蒸腾作用的影响大于光合作用。随岱的增加，不同部位叶片砌和蒸腾速率（Tr）呈上升趋势，总体来看，各部位叶片开峰值出现时间与岱峰值出现时间基本一致，二者均滞后于砌峰值出现时间。（3）烤烟不同部位叶片主要决策变量均为光合有效辐射（PAR），主要限制变量均为大气温度（Ta）。由此可知，要提高烤烟不同部位叶片砌，需采取一定措施如增大株间距离来提高PAR，控制各部位叶片所处微环境乃，进而改善各部位叶片温度（Tl），基本保持大气CO2浓度（Ca）不变。

Study on Photosynthetic Characteristics of Leaves in Different Positions in Flue-cured Tobacco

To confirm the photosynthetic physiological mechanism qf growth and quality variance formation of the flue-cured tobacco leaves in different stalk positions, the photosynthetic characteristics of the flue-cured tobacco leaves in different stalk positions and environmental factors that affect photosynthesis were discussed. Taking ＇Yuyan 10＇ as the materials, the photosynthetic characteristics and environmental factors diurnal variation process of the flue-cured tobacco leaves ＇in different stalk positions were determined in the fast grow stage, and path analysis method was used to analyze the direct and indirect effects of environmental factors on the net photosynthetic rate （Pn）. The results indicated that： （1） the Pn diurnal variation of the leaves in different stalk positions were ＇unimodal type＇. The Pn daily average values of the upper, middle and lower leaves were 13.25, 11.71, 6.26 μmol CO2/（m^2. s） and the value of the lower leaves was significantly lower than the upper and middle leaves. （2） Stomatal conductance （Gs） had greater influence on flue-cured tobacco transpiration than the photosynthesis. With the increase of the Gs, the Pn and the transpiration rate （Tr） of the flue-cured tobacco leaves in different stalk positions showed ascendant trend. Overall, the peak time of the blade Tr and Gs was consistent, while they both lagged behind the peak time of Pn. （3） The main decision variables of theflue-cured tobacco leaves in different stalk positions were the photosynthetic active radiation （PAR） and the main restriction variables were the atmospheric temperature （Ta）. Therefore, to improve the Pn of the flue- cured tobacco leaves in different stalk positions, certain measures such as reducing the planting density needed to be taken to increase the PAR appropriately and control the microenvironment Ta, thereby improving the various parts of the blade temperature （Tl）. Keeping atmospheric CO2 concentration （Ca） basically constant was also necessary.