Effects of flooding on the photosynthetic response of Hemarthria altissima to drought
In the hydro fluctuation belt of the Three Gorges Reservoir Area (TGRA) plants are subjected to a long period of flooding which can affect their growth and survival. In additional, when the flooding recedes, plants may experience drought stress that can also affect their growth and photosynthesis. Thus, screening for suitable species that can survive these fluctuating conditions is necessary for the successful restoration of vegetation to the hydro fluctuation belt of the TGRA. Hemarthria altissima, a plant commonly found in the TGRA, may be one such suitable plant in the remediation process of the hydro fluctuation belt. H. altissima has a high survival rate and is well adapted to flooding; however, the response of these plants to drought following flooding and the physiological mechanisms behind this response are unknown. In order to characterize these mechanisms, we studied leaf gas exchange, stomatal limitation (Ls) and water use efficiency (WUE) in H. altissima under different water regimes in the hydro fluctuation belt of the TGRA. We applied the following six water regimes: control (CK, soil water content 60% 63% of soil water field capacity) soil surface flooding (SF, with water level 5 cm above the soil surface) total flooding (TF, with water level 1 m above the soil surface) control drought (CD,