What to do to solve the riddle of vine rootstock induced drought tolerance
Climate change will increase the frequency of water deficit situation in some European regions, by the increase of the evapotranspiration and the reduction of rainfalls during the growing cycle. This requires finding ways of adaptation, including the use of plant material which is more tolerant to drought. In addition to the varieties used as scions that result in the typicality of wines, rootstocks constitute a relevant way of adaptation to more stressful environmental conditions.
The rootstock genotype impacts grapevine functioning at three levels: the absorption of water, the water transport and the water consumption. The variability of root anatomy, root depth and water extraction capacity may explain water deficit responses differences observed or measured between rootstocks in pot or in field experiments. Whole root hydraulic conductance differed between sensitive and tolerant rootstocks. Vine water use are related to the leaf area and the vigor conferred, but also to regulatory processes, partially independent during the day and the night. Gas exchanges regulation along the day and night but also with the variation of the water status, i.e. the transpiration plasticity to water status, is in fact partially controlled by rootstocks.
Despite the empirical knowledge and the increasing interest dedicated research on grapevine rootstocks, the mechanisms involved in all these responses to water deficit remain poorly understood. Data from the literature and recorded in Bordeaux will be synthesized. Some challenges have to be met to get further crucial information about the traits conferring a higher adaptation to water deficit in order to speed up the selection of new rootstocks tolerant to drought. These challenges, i.e. the variability of the responses due to water status scenario (the intensity and the occurrence in the cycle of the water deficit), the choice of the traits measured and their plasticity, as well as rootstock scion interactions, will be discussed.
Issue: ICGWS 2023
1 EGFV, University of Bordeaux, Bordeaux Sciences Agro, INRAE, ISVV
2 Department of Agricultural and Environmental Sciences, University of Milan, via G. Celoria 2, 20133 Milano, Italy