Study on Photosynthesis of Populus euphratica in Relation to Groundwater Depths and High Temperature in Arid Environment Made Progress

The stream flow of the lower reaches of the Tarim River has sharply decreased and the temperature of the Tarim Basin experienced significant monotonic increases which exacerbate the environmental stresses of Populus euphratica growth.

Dr. Honghua ZHOU, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, analyzed the photosynthetic characterization of Populus euphratica and their response to increasing groundwater depth and temperature. The results showed that the growth condition and photosynthetic characterization of P. euphratica were closely related to groundwater depth. The rational groundwater depth for the normal growth and photosynthesis was 3–5 m. However, P. euphratica could keep normal growth through a strong drought resistance depended on the stomatal limitation and osmotic adjustment when it faced mild or moderate drought stress, respectively, at a normal temperature (25°C). High temperature (40°C) significantly reduced photosynthesis and drought stress exacerbated the damage of high temperature to the photosynthesis. Moreover, P. euphratica would prioritize the resistance of high temperature when it encountered the interaction between heat shock and water deficit through the stomata open unequally to improve the transpiration of leaves to dissipate overheating at the cost of low water use efficiency, and then resist water stress through the osmotic adjustment or the stomatal limitation.

In conclusion, the hypothesis that “The interaction between heat shock and water deficit has a more severe effect on the photosynthesis of P. euphratica than each of these stress conditions experienced individually.” was tested.

The result was published in the Photosynthetica, 2010, 48(2): 257-268.