土壤水分对金银花叶片气体交换参数及水分利用效率的影响

Effects of Soil Moisture on the Gas-exchange Parameters and Water Use Efficiency of Lonicera japonica Thunb.

利用CIRAS－2型便携式光合作用仪，测定了不同土壤水分条件下3年生金银花叶片的净光合速率（Pn）、蒸腾速率（Tr）及水分利用效率（WUE）等生理参数的光响应过程，阐明其气体交换参数及水分利用效率对土壤水分和光合有效辐射的响应规律，探讨了金银花正常生长发育所需的土壤水分和光照条件。结果表明：金银花叶片的P。一及WUE对土壤水分和光合有效辐射的变化具有明显的阈值响应；金银花叶片正常生长（同时具有较高Pn和WVE）的适宜土壤质量含水量（Wm）为121～206g·kg^-1，适宜的光合有效辐射为600～1600μmol·m^-2·s^-1；Wm为172g·kg^-1左右为“最佳高产高效水”，最佳光合有效辐射为800～1000μmol·m^-2·s^-1。以光合生理参数为指标对金银花土壤水分有效性及生产力进行分级与评价，确定既在62g·kg^-1以下为“无效水”；Wm在234g·kg^-1以上和62～90g·kg^-1阈值内属于“低产低效水”；在121～145g·kg^-1阈值内为“中产中效水”；在172～206g·kg^-1阈值内为“高产高效水”。

Little is known about the optimum soil moisture and light Thunb. Using CIRAS-2 portable photosynthesis system, the light intensities for the growth of Lonicera japonica responses of photosynthetic and physiological parameters of three years old leaves, such as net photosynthetic rate （ Pn ）, transpiration rate （ Tr ） and water use efficiency （WUE） were thus measured under different soil moisture conditions. The results showed that Pn, Tr and WUE of leaves have critical response to the levels of soil moisture and the variation of photosynthetic active radiation （PAR）. In order to maintain the plant growing normally and having higher P, and WUE synchronously, the fitting mass water content （Wm） was about 121--206 g·kg^-1, and the fitting PAR was in the range of 600--1 600 μmol·m^-2·s^-1 . The ＂optimal high productivity and high efficiency water＂ of Wm was about 172 g · kg^-1 , and the optimal PAR was in the range of 800--1 000 μmol·m^-2·s^-1 Based on photosynthetic physiological parameters, the soil water availability and productivity of Lonicera japonica were classified and evaluated. The results showed that on Lonicera japonica woodland, the Wm less than 62 g · kg^-1 belonged to ＂Non-available water＂ ; in the range of 62 -90 g · kg^-1 and more than 234 g· kg^-1, ＂low productivity and low efficiency water＂ ; 121--145 g · kg^-1, ＂Middle productivity and middle efficiency water＂; 172--206 g · kg^-1, ＂High productivity and high efficiency water＂.