秋华柳种群光合作用性能对人工调节水位消涨的响应.

[Objectiv] The present paper aimed to study the changes of photosynthetic performance at different stages during the whole growth period after summer flooding, and to reveal the adaptation mechanism of photosynthetic performance of the Salix variegata Franch populations to the changes of aquatic ecological environment, so as to provide scientific basis for the protection and utilization of this species. [Method] In the study, the S. variegata Franch populations in Guanzhou Island, downstream of the Three Gorges Dam, were used as the test materials. By using the method of field investigation and measurement, different gradient measurement times were set: at the initial stage of exposure (exposure for 60 days）, every 10 days, and at the early, middle and late stages of the whole growth period (exposure for 50 days, 110 days and 170 days）, the photosynthetic performance of the plants were measured respectively, in order to reveal the effects of artificial regulation of rivers on the photosynthetic performance of plant populations and plant growth. [Result] The photosynthetic performance of the S. variegata populations recovered rapidly during the early exposing stage under the regulated water level fluctuation pattern. The photosynthetic rate (Pn）, stomatal conductance (Gs) and transpiration rate (Tr) of plants increased significantly with the growth recovery process. The characteristic values of light response curves including the maximum net photosynthetic rate(Pn max), apparent quantum efficiency (AQY) and photosynthetic pigment content also increased rapidly. The photosynthetic performance of the populations ranked the highest at the early growth stage, followed by the late and middle growth stage in the whole growth period. The net photosynthetic rate increased by 59. 39% and 30. 77% compared with that of the middle and late growth stages, respectively. A similar trend of variation in the characteristic values of light response curve and photosynthetic pigment content was also observed. Pearson correlation analysis indicated that the related parameters of photosynthetic performance of S. variegata populations were significantly correlated with soil water content, and the transpiration rate and carotenoid content were significantly correlated with water level. [Conclusion] The decrease of soil water content and exposing time caused by the river regulation by the large-scale water conservancy and hydropower projects had a serious impact on the photosynthetic performance of S. variegata populations, and further affected the growth of the populations. [ABSTRACT FROM AUTHOR]