楸树无性系光合特性研究

Photosynthetic Characteristics of Catalpa bungei Clones

以10个楸树无性系为试验材料,利用Li-6400光合测定仪对其光合特性进行了比较研究。结果表明：楸树净光合速率（Pn）日变化为典型的双峰曲线,气孔限制是光合＂午休＂的主要调节因素。楸树所有无性系光合作用对光照强度（PAR）单一生态因子水平的响应均可以用二次方程描述。楸树的光补偿点（LCP,11.37~57.4μmol.m-2.s-1）和CO2补偿点（CCP,57.73~77.06μmol.mol-1）在10个无性系间存在显著差异。10个楸树无性系的净光合速率、气孔导度、蒸腾速率和瞬时水分利用效率在无性系间存在极显著差异。在光饱和点（LSP）条件下,10个无性系净光合速率处于18.8~24.4μmol.m-2.s-1之间。环境因子与光合指标存在显著的相关关系,PAR和空气湿度（RH）对楸树无性系瞬时Pn影响最大。

With the help of Li-6400 photosynthesis measuring system,10 Catalpa bungei clones were studied.The comparative research of photosynthetic characteristics of the ten clones showed that the daily net photosynthetic rate of C.bungei presented a typical double-peak curve,stomatal limitation was a major regulating factors of photosynthetic ＇noon depression＇.The photosynthetic response of all the ten C.bungei clones to the light intensity（PAR） could be described as a quadratic equation.There were significantly differences in light compensation points and CO2 compensation points among the ten C.bungei clones.The LCP and CCP were between 11.37～57.4 μmol·m-2·s-1 and 57.73～77.06 μmol·mol-1.The net photosynthetic rate,stomatal conductance,transpiration rate and water use efficiency were differed significantly among 10 clones.The range of Pn was between 18.8～24.4 μmol·m-2·s-1.Under the condition of LSP,a significant correlation between ecological environmental factors and physiological indicators was observed.PAR and RH were the most effective factors for Pn.