Interactive effects of elevated CO2 concentration and drought stress on some physio-morphological and biochemical characteristics of Quercus brantii seedlings

Abstract

The elevated atmospheric CO₂ concentration is expected to increase plant growth and productivity and improve water use efficiency. Hence, elevated CO₂ is considered to mitigate to some extent the adverse effects of drought. We aimed to investigate physio-morphological and biochemical responses of 2-year-old Persian oak (Quercus brantii Lindl.) seedlings to the elevated CO₂ concentration and drought alone and when combined. Persian oak seedlings were grown in growth chambers at two CO₂ concentrations (ambient; 380 ppm and elevated; 700 ppm) and two water regimes (well-watered; 100% of field capacity and water stress; about 50% of this value) for one growing season (8 months). The results showed elevated CO₂ concentration significantly increased collar diameter, shoot height, leaf area, biomass production, root volume, photosynthetic traits, leaf pigments (chlorophyll and carotenoids) content, and relative leaf water content. While, it decreased total N content of leaves, proline content, electrolyte leakage, Malondialdehyde content, and antioxidant enzymes (catalase, peroxidase, and ascorbate peroxidase) activity in comparison to ambient CO₂ concentration. However, the root length was unaffected in response to elevated CO₂. In contrast, drought had an adverse effect on the studied traits except for root length. These effects were alleviated by the presence of CO₂, as apparent in physio-morphological and biochemical traits. Our findings suggest that in different proposed climate change scenarios, Persian oak trees may tolerate drought in the presence of elevated CO₂.