Carbon assimilation in oak (Quercus spp.) populations under acute and chronic high-temperature stress

Abstract

This study tried to evaluate the influence of high temperatures (HT) on carbon assimilation of two oak species (Quercus cerris and Quercus robur). The screening of their populations, which are assumed to have a different resistance and acclimatization potential to adverse environmental conditions, can provide essential information for its implementation in reforestation strategies. By employing principal component analysis, the aim was to determine the most variable physiological characteristics of plants exposed to extremely HT during vegetation periods. After 2 d of HT treatment, a significant decline of photosynthetic and transpiration rates, and stomatal conductance were observed in plants of all investigated populations. The decrease of photosynthetic parameters after 2 d of HT treatment was regulated by the stomatal closure which caused the limitation of CO2 assimilation. Contrary, a chronic HT stress led to an increase in gs and inhibition of photosynthesis at the level of carboxylation.

Keywords

• fluorescence; gas exchange; heat stress; random forest analysis; water-use efficiency.