The stomatal dynamic response of hybrid poplars in a changing climate: under drought and heat combined stresses, impact on whole-plant transpiration efficiency

S. BERVILLE, D. COMBEMALE, C. BURE, J.C. OLRY, M-N. VAULTIER, D. LE THIEC
UMR SILVA, Lorraine University-AgroParisTech-INRAE, F-54000 Nancy, France

Periods of drought and heatwaves have been planned to be more frequent and intensives. A key for plants to adapt to this changing-climate world is to optimize the stomatal dynamic to balance the photosynthesis and water loss. Recent findings were able to show significant variability of stomatal dynamics between genotypes, but not much is known about factors influencing stomatal dynamics and its consequences on biomass production, transpiration and water-use efficiency (WUE). Less is known about the impact of heat and drought combination on stomatal dynamic. To better study the opening and closing stomata, two hybrids populus (P. deltoides x P. nigra; Carpaccio and I-214) chosen on their sensitivity to drought were studied. We explored the stomatal behavior with changing irradiance and high VPD after a heatwave (36°C) combined or not with moderate drought. Our results show differences on the stomatal dynamics between genotypes in control and stress conditions. Moreover, I-214 has a higher sensitivity to drought stress and also to drought combined with heatwave than Carpaccio. We will show correlations between all parameters and whole-plant water use.