盐分胁迫下杠柳叶片光合特性的光响应研究

Light Response of Periploca sepium Bunge Leaves Physiological Parameters under Salt Stress

利用CID型便携式光合作用仪测定不同NaCl浓度下杠柳叶片净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）、水分利用效率（WUE）及光能利用率（LUE）生理参数的光响应过程，阐明盐分胁迫下其对光照响应的规律，探讨有利于杠柳正常生长的盐分浓度和光照条件。结果表明：（1）各盐分浓度下杠柳叶片光补偿点（LCP）在21．89～65．05μmol．m^-2·S^-1之间变动，介于阴性植物与阳性植物之间；杠柳随土壤盐分的不同，其光合作用参数对光照强度表现出一定的适应性和可塑性；50mmol·L^-1盐分浓度下杠柳光合同化能力最强，最有利于其干物质的积累，表现出一定的耐盐性。（2）轻度的盐分胁迫（小于50mmol·L^-1）可以提高杠柳叶片的Pn、Gs、WUE和LUE，而盐分胁迫对杠柳的Tr有抑制作用，并随着盐分浓度的增加其抑制作用愈强烈。（3）维持杠柳正常生长的土壤盐分浓度小于50mmol·L^-1，最佳PAR为1000～2000μmol·m^-2·S^-1；而保持杠柳最大WUE和LUE的光照强度分别为800和100μmol·m^-2·S^-1。

In order to clarify the regular pattern which Periploca sepium Bunge responds for the salt stress and investigate the optimum saline concentration and light condition for the growth of P. sepium Bunge,we measured the light response of photosynthetic parameters, such as net photosynthetic rate（Pn）,transpiration rate（Tr） ,stomatal conductance（Gs） ,water use efficiency （WUE） and light use efficiency（LUE） ,to P. sepium Bunge in different saline concentrations with CID portable photosynthesis system. The results show：（1）The LCP of P. sepium Bunge varies from 21.89-65.05 μmol·m^-2·S^-1 under different of saline concentrations. It means that P. sepium Bunge is between the negative and positive plants. With the different of soil salinity, the photosynthesis of P. sepium Bunge for illumination intensity shows some adaptability and plasticity. The photo assimilation ability of P. sepium Bunge is stronger under the 50 mmol . L^-1 Of saline concentration. The accumulation of dry matter is enhanced and the plants show salt resistance to a certain extent. （2）The light salt stress less than 50 mmol . L^-1 carl improve the Pn ,Gs ,WUE and LUE of P. sepium Bunge leaves,and the salt stress has inhibitory effect to Tr ,and the inhibitory effect is positive related with the saline concentration. （3）In order to maintain the normal growth,the fitting saline concentration of soil is less than 50 mmol . L^-1 ,and the optimum PAR is between 1 000-2 000 μmol·m^-2·S^-1 ,and the illumination intensity to maintain the high WUE and LUE is separately 800 μmol·m^-2·S^-1 and 100μmol·m^-2·S^-1.