沙棘干物质形成的光合作用机制

用LI-6400光合仪在黄土高原中部系统测定了人工沙棘林的各种光合生理指标，主要结果为：叶光强响应曲线暗呼吸速率、表观量子效率、最大光合速率、光补偿点和光饱和点分别为：-3．677μmol·CO2·m^-2·S^-1、0．0517mol·mol^-1、7．367μmol·CO2·m^-2·S^-1、71．15μmol·m^-2·s^-1和213．7μmol·m^-2·S^-1。CO2浓度响应曲线参数CO2补偿点、CO2饱和点、暗呼吸速率、羧化效率及最大光合速率分别为150．00μmol·mol^-1、506．834μmol·mol^-1、-1．100μmol·CO2·m^-2·s^-1、0．0063mol·mol^-1和3．01μmol·CO2·m^-2·s^-1。光合速率日变化为左偏单峰曲线，峰值在10：00～12：00时。沙棘的ETR变化与光合速率同步，最大荧光产量Fm＇在叶片转入黑暗后逐渐上升，17min左右趋于稳定；qP和qN变化不明显；当光适应的叶片转入黑暗下之后，NPQ开始下降，25min左右达到稳定。沙棘荧光强度响应曲线变化与其普通光强响应曲线类似，参数暗呼吸速率、光的补偿点、光的饱和点、最大光合速率和表观量子效率其值分别为-0．511μmol·CO2·m^-2·s^-1、14．72μmol·m^-2·s^-1、259．6μmol·m^-2·s^-1、8．494μmol·CO2·m^-2·s^-1和0．0347mol·mol^-1。沙棘叶片荧光CO2响应曲线与普通光源CO2响应曲线变化规律相似，荧光CO2响应曲线参数暗呼吸速率、CO2补偿点、CO2饱和点、最大光合速率以及羧化效率分别为-0．0914μmol·CO2·m^-2·s^-1、87．12μmol·mol^-1、745．212μmol·mol^-1、17．90μmol·CO2·m^-2·s^-1和0．0077mol·mol^-1。

On Photosynthetic Mechanism of Seabuckthorn Plantations in the Loess Plateau

The different parameters of photosynthetic physiology for seabuckthorn plantation in the Loess Plateau have systematically been determined with LI-6400 Photosynthesis system, which main results as follows： The parameters of the light response curve such as foliar dark respiration rate, apparent quantum efficiency （AQE）, maximum photosynthetic rates, light compensation point （LCP） and light saturation point （ LSP ） are - 3. 677μmol·CO2·m^-2 ·s^-1, 0. 0517mol·mol^-1, 7.367μmol·CO2·m^-2·s^-1 , 71.15 μmol·m^-2·s^-1 and 213.7μmol·m^-2·s^-1 respectively. The parameters of CO2 concentration response curve such as CO2 compensation point, CO2 saturation point, dark respiration rates, carboxylation efficiency （ CE ） and maximum photosynthetic rates are 150. 00μmol·mol^-1 , 506. 834μmol·mol^-1 , - 1. 100μmol· CO2·m^-2·s^-1, 0. 0063 mol·mol^-1 and 3.01μmol·CO2·m^-2·s^-1 respectively. The daily variation of photosynthetic rate is left skewed mono peak curve, which maximum value appears at 10：00-12：00. The change of Electron Transport Rate （ETR） synchronizes with the photosynthetic rate. Fro＇ （maximal fluorescence during a saturating light flash） raises gradually up when leaves are turned to dark, which stabilizes after about 17 minutes interval. The qP （Photochemical quenching） and qN do not vary evidently. When the light energy is being used instantaneously, a low light intensity adopted well the light energy capture efficiency, NPQ （Non Photochemical Quenching） goes gradually down, which stabilizes after about 25 minutes. The fluorescent light response curve for plants is similar to the variation of common light response curve for plants, the fluorescent CO2 curve for plant is similar to that of common light source curve.