Photosynthetic Acclimation of a Desert Species Nitraria tangutorum to Long Term Rain Addition in North-Western China

Precipitation patterns might change because of global climate change in mid-latitude regions, while the study on how photosynthetic physiological characteristics acclimate and the response mechanisms to long term rain addition of desert plant in arid and semi-arid regions on the Northwest of China are still relatively scarce.In order to understand the acclimatization and explore the adaptive mechanism of typical desert plant Nitraria tangutorum Bobrov to rain addition, gas exchange parameters and photosynthetic physiology characteristics of N. tangutorum at the eastern edge of the Ulanbuh Desert on the Northwest of China under five rain addition treatments (increased 0%, 25%, 50%, 75% and 100% of local mean annual precipitation, respectively) were measured.The results show that photosynthetic capacity enhanced after rain addition.The impact extent of precipitation on photosynthesis was related to rain addition amount which was not less than 75% (110 mm) rain addition played significantly accelerated effects on photosynthesis and transpiration.The supplement watered plants carbon and water exchange were affected significantly which indicated that there was a process for N. tangutorum to adapt to the increased precipitation.The apparent quantum efficiency (AQY), light saturation point (LSP), initial carboxylation efficiency (CE) and CO 2 saturation point (CSP) increased, indicating an enhanced activity of carboxyl enzyme and increased the capacity of N. tangutorum to use light and carbon dioxide.Therefore, under global change scenario, N. tangutorum would improve the photosynthetic capacity and mediate the function of photosynthetic organization to adapt to new water conditions in the future.