土壤湿度对黄荆光合作用光响应过程的影响

Effect of Soil Moisture on Light Response Process for Vitex negundo

以黄荆为试材,利用CIRAS-2型全自动便携式光合作用测定系统,测定并分析了不同土壤湿度对黄荆光合作用光响应过程的影响,以期为黄荆良好的生长发育提供坚实的植物生理生态学基础。结果表明:黄荆的光合速率、蒸腾速率、叶片水分利用效率、光能利用效率对土壤含水量和光合有效辐射的变化都有明显的阈值响应。根据Pn对光合有效辐射的响应特征得出,适度的土壤水分胁迫能提高黄荆对光照的适应能力。根据Pn和WUE对土壤湿度的响应特征得出,轻度水分胁迫能提高黄荆的Pn,当土壤相对含水量RWC约为57.7%时,黄荆的Pn达到最大值;中度水分胁迫能够提高黄荆的WUE,在RWC约为48.8%时,黄荆的WUE达到最大值。综合Pn、WUE与土壤湿度的定量关系认为,黄荆适宜的土壤湿度时RWC为39.6%~57.7%。在此土壤湿度范围内,黄荆在维持较高光合速率的同时,也有较高的水分利用效率。

In order to provide a solid foundation for the analysis ot plant physlologacal ecology, the effects of soil moisture on photosynthetic light response process of Vite：r negundo were studied by CIRAS-2 automatic and portable photosynthesis measuring system made in the USA. The results showed that the photosynthesis rate （Pn）,transpiration rate （Tr）,leaf water use efficiency （WUE）, light use efficiency （LUE） had obvious threshold response to soil moisture and photosynthesis active radiation（PAR）. According to Pn of PAR response characteristics of soil moisture,the adaptability to light could be improved in moderate stress. According to the response characteristics of Pn and WUE on soil moisture, Pn could be improved in mild water stress~ when the soil relative water content （RWC） was about 57.7% ,Pn reached the maximum value. WUE could also be improved in moderate water stress, and it reached the maximum value in 48.8%. Together the quantitative relationship between Pn,WUE and soil moisture,Vitex negundo could also maintain a high photosynthetic rate and water use efficiency in the range of soil moisture 39.6 % to 57.7%.