Increasing atmospheric [CO₂] from glacial to future concentrations affects drought tolerance via impacts on leaves, xylem and their integrated function

Abstract

Summary Changes in atmospheric carbon dioxide concentration ([CO2]) affect plant carbon/water trade-offs, with implications for drought tolerance. Leaf-level studies often indicate that drought tolerance may increase with rising [CO2], but integrated leaf and xylem responses are not well understood in this respect. In addition, the influence of low [CO2] of the last glacial period on drought tolerance and xylem properties is not well understood.We investigated the interactive effects of a broad range of [CO2] and plant water potentials on leaf function, xylem structure and function and the integration of leaf and xylem function in Phaseolus vulgaris.Elevated [CO2] decreased vessel implosion strength, reduced conduit specific hydraulic conductance, and compromised leaf specific xylem hydraulic conductance under moderate drought. By contrast, at glacial [CO2], transpiration was maintained under moderate drought via greater conduit specific and leaf specific hydraulic conductance in association with increased vessel implosion strength.Our study involving the integration of leaf and xylem responses suggests that increasing [CO2] does not improve drought tolerance. We show that under glacial conditions changes in leaf and xylem properties could increase drought tolerance, while under future conditions greater productivity may only occur when higher water use can be accommodated.

Winners always win: growth of a wide range of plant species from low to future high CO2

“…2013) as does water supply (Ward et al. 1999; Medeiros and Ward 2013) and temperature (Cowling and Sage 1998; Ward et al. 2008).…”

Examining plant physiological responses to climate change through an evolutionary lens

“…A focus on physiology is critical because these processes scale from individual to ecosystem levels. For example, [CO 2 ] rise and climate change that alter photosynthetic rates may shift plant growth rates, overall productivity, and resource use (Ainsworth and Rogers, 2007;Norby and Donald, 2011;Medeiros and Ward, 2013). Other physiological responses to altered climate include increasing leaf sugars with elevated [CO 2 ], which may influence major life history traits such as flowering time and fitness via sugar-sensing mechanisms (Springer et al, 2008;Wahl et al, 2013).…”

Elevated [CO2] alleviates the impacts of water deficit on xylem anatomy and hydraulic properties of maize stems

“…We observed that A stem and also K max was correlated with the supported A leaf across all treatments (Figure ). Water transport through the stem xylem is essential for replacing water loss during leaf transpiration, so it is often assumed that greater leaf area as a result of environmental change can increase the transport capacity of the xylem to meet water demand (Atkinson & Taylor, ; Gebauer & BassiriRad, ; Plavcová & Hacke, ; Medeiros & Ward, ). Conversely, assimilation can drive leaf development until a limitation on stem development limits further leaf area development.…”

“…The centrifuge method was first and widely used to determine the stem xylem cavitation vulnerability curve (Alder, Pockman, Sperry, & Nuismer, ) and also reliable for nonwoody plants (e.g., Maize, Li et al, ; Sunflower, Rico et al, ; Phaseolus, Medeiros & Ward, ; Arabidopsis, Tixier et al, ). We used a centrifuge (H2050R‐1; Xiangyi, China) and a custom‐built rotor, modified to suit maize stem segments based on the design on the website of Sperry lab (http://sperry.biology.utah.edu/methods.html) in 2016.…”