黄河三角洲柽柳与芦苇光合特性比较

选取黄河三角洲典型植被优势种柽柳(Tamarix chinensis)和芦苇(Phragmites australis),以全天自然光的日变化为光照梯度,研究两者对光强的响应规律,比较它们的光合荧光特性。结果显示,柽柳具有较高的光补偿点和光饱和点,在高光强时蒸腾依然旺盛,并且气孔调节能力较强,以反应中心状态转换和可逆失活进行能量调节,最大可能减少无谓的能量散失,光系统有效量子产量高,从而保证了较高的电子传递速率;芦苇气孔调节和光能利用能力较柽柳低,在高光强时出现净光合速率和蒸腾速率的降低及电子传递饱和现象,随光照增加,光系统有效量子产量下降较大,采取热耗散的方式散失过剩光能以避免光损伤。本次光响应研究的尝试证明其具有一定的合理性,但仍有待进一步验证。

A comparison of photosynthetic characteristics between Tamarix chinensis and Phragmites australis in the Yellow River Delta

Dominant species of typical vegetation in the Yellow River Delta,Tamarix chinensis and Phragmites australis,were chosen for the study of their photosynthetic characteristics.We use the diurnal changes of natural sunlight to simulate the photosynthetic active radiation gradations.From the result, we detect that T.chinensis characterizes the high level of light compensation point and light saturation point.The transpiration is strong and the stomatal regulation is effective under the high light condition.The state transition and reaction center's turnover are the main pathway to energy dissipation so that the thermal loss can be avoided to keep high photosystem II quantum efficiency and electron transport rate.P.australis is different from T.chinensis in light and water utilization,and the ability of stomatal regulation is lower in controlling photosynthesis and transpiration.When the light is becoming stronger,quantum efficiency of photosystem II decreases rapidly and the electron transport curve is becoming smoothly.Excess of excitation energy is de-excited by thermal dissipation processes in case the photodamage happened.This experiment for testing a new light-response method is successful and persuadable,but it still needs to be tested further.