CO2 effects on the waterlogging response of 'Gisela 5' and 'Gisela 6' (Prunus cerasus x Prunus canescens) sweet cherry (Prunus avium) rootstocks

Climate change is submitting countries of the Mediterranean arc to periods of drought alternating with heavy rain and waterlogging. Eventual floods along with the rising CO2 in the atmosphere present an unpredictable scenario that affects crop survival. The effect of both stresses combined has been studied in sweet cherry plants. 'Gisela 5' and 'Gisela 6' were evaluated as rootstocks of the sweet cherry cultivar 'Burlat'. Plants were placed in a controlled-climate chamber for 7 days, then they were submitted to waterlogging for another 7 days and the response to this stress and the subsequent recovery were studied (7 more days). The experiment was carried out at 400 μmol mol−1 CO2 (ambient CO2) and 800 μmol mol−1 CO2, at 26 °C, and plant water status and growth, net CO2 assimilation, transpiration, stomatal conductance, water potential, chlorophyll fluorescence, relative water content, anions content, proline, lipid peroxidation, soluble sugars, and starch were measured. Differences in the response and in its intensity were detected in both rootstocks. Some parameters - such as photosynthesis, soluble sugars, starch, TBARS, and NO3− - varied depending on the CO2 conditions and the waterlogging effect. Elevated CO2 was able to increase photosynthesis and thereby help plants to overcome waterlogging.