青海湖防沙治沙区沙棘光合特性与光响应特征研究

为研究青海湖固沙区人工沙棘的光合特性，以青海湖典型的固沙植物沙棘为研究对象，对其光合、蒸腾特性及主要影响因素进行了测定．结果表明，沙棘的光合具有明显的日变化规律，呈双峰型，光合作用速率P。在12：00左右出现峰值，为21．28μmol／（m^2·s）（文中均以CO2固定量为准），日平均值为13．23μmol／（m^2·s），具有“光午休”现象．蒸腾速率Tr与气孔导度Gs日变化动态也呈双峰型，光合作用有效辐射（Rpa）、空气温度丁日及水汽压强差（Pvd）变化规律基本一致，空气湿度（Hr）变化规律则相反；沙棘的Pn，Tr与Rpa，Ta，Gs及pvd呈显著相关，其中，Tr和Pvd影响最为显著；沙棘叶片的水分利用效率（Ewu）的光响应曲线表明，光合有效辐射达到400μmol／（m^2·s）时，Ewu最大．对青海湖防沙治沙与生态恢复有重要的参考价值．

Study on Photosynthetic Characteritcs of Hippophae Rhamnoides Linn and Key Impact Factors in Areas of Desertification Combating around Qinghai Lake

The photosynthetic rate,transpiration rate and key impact factors of Hippophae rhamnoides Linn were measured by using the LI-6400 portable photosynthesis system in sand areas around Qinghai Lake.The results showed that the diurnal variation of net photosynthetic rate,transpiration rate and key impact factors were obvious changing rules.And the daily curve of photosynthetic rate and transpiration rate were the double-peak type curves.The midday depression of photosynthesis was obvious.Photosynthetic available radiation(PAR),air temperature(Ta),and the stomata conductance had positively relationship with the net photosynthetic rate.And the transpiration rate had positively relationship with the vapor pressure deficit.The response curve of water use efficiency(WUE)of Hippophae rhamnoides Linn to PAR showed that when PAR was 400 μmol/(m2·s),WUE arrived at the highest value.The research of the water use efficiency(WUE)of Hippophae rhamnoides Linn will be very important for studying on Hippophae rhamnoides Linn drought resistance mechanism.