Photosynthesis of Populus euphratica in relation to groundwater depths and high temperature in arid environment, northwest China

Abstract

The photosynthetic characterization of Populus euphratica and their response to increasing groundwater depth and temperature were analyzed based on net photosynthetic rate (P N ), stomatal conductance (g s ), intercellular CO 2 concentration (C i ), transpiration rate (E), water use efficiency (WUE) and stomatal limitation (L s ) measured by a portable gas-exchange system (LI-6400) in the lower reaches of the Tarim River. Light-response curves were constructed to obtain light-compensation and light-saturation points (LCP and LSP), maximum photosynthetic rates (P max ), quantum yields (AQY), and dark respiration rates (R D ). The growth condition of P. euphratica, soil moisture, and groundwater depth in the plots were analyzed by field investigation. 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, the stress groundwater depth for mild drought was more than 5 m, for moderate drought was more than 6 m, for severe drought was more than 7 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 P N 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 WUE, and then resist water stress through the osmotic adjustment or the stomatal limitation.

Morphological, anatomical and physiological leaf traits of Q. ilex, P. latifolia, P. lentiscus, and M. communis and their response to Mediterranean climate stress factors

“…Limitations to plant growth imposed by the Mediterranean climate are mainly due to plant carbon balance in response to stress factors (Galmés et al 2007). In particular, water stress associated to high air temperatures and an excess of light during summer, may result in a chronic photo-inhibition or down-regulation of photosynthesis causing a marked decrease in CO 2 assimilation (Zhou et al 2010). Carbon balance depends on the ratio between photosynthesis and respiration (Lambers et al 1998), and both these factors change in response to climatic conditions (Baldocchi and Amthor 2001).…”

Adaptation strategies of desert riparian forest vegetation in response to drought stress

“…Each of these response types promotes different abilities to resist and withstand stress. In general, prior to more fundamental damage incurred by extreme and sudden water shortage, plants respond adaptively to most stress factors by effectively selecting an optimized solution (Zhou et al ., ). An in‐depth study of the adaptation mechanisms with which plants respond to drought stress is therefore imperative for understanding the differences in drought adaptation methods and drought‐resistance characteristics of various plants.…”

Hydraulic redistribution of soil water in Populus euphratica Oliv. in a central Asian desert riparian forest

“…So, many studies were carried out to reveal the appropriate ecological groundwater depth. These studies tried to establish a simple and effective way to reflect the complex plant–water relationship, using a variety of different perspectives and scales such as using biochemical parameters (Chen et al ., ; Zhuang and Chen, ; Ruan et al ., ), photosynthesis characters (Chen et al ., ; Zhou et al ., ), leaf water potential of individual plants (Fu et al ., ) or by studying community stability(Chen et al ., ; Hao et al ., ; Hao et al ., ) and groundwater quality(Li et al ., ). Although considerable research has been carried out, water use strategies such as hydraulic lift have not been considered.…”