Christopher Chen,* Nina Romero, and M. Andrew Walker
*University of California Davis, 1 Shields Ave, Davis, CA 95616 (codchen@ucdavis.edu)

As our climate changes and temperatures rise, water scarcity and high evapotranspiration has led to a greater buildup of sodium chloride in agricultural soils. Grapevines, like most perennial crops, are glycophytic and lack sufficient responses to high soil salinity in their immediate rooting zone. Salt toxicity can lead to detrimental effects on growth, yield, and overall vine health. There is a need to understand how NaCl affects grapevine photosynthesis and address the potential for different forms of salt tolerance in grapevines. Measurements of transpiration, stomatal conductance, and net assimilation rates were conducted across two trials on grapevine rootstocks exposed to NaCl concentrations of 0, 25, 50, 75, and 100 mM. Because several rootstock selections varied between experiments, five selections were shared across both trials for continuity. The preliminary trial tested the photosynthetic response of eight rootstocks when irrigated with NaCl solution at concentrations of 0, 25, 75, or 100 mM NaCl over 21 days. Differences between selections were only significant at concentrations of 75 mM or greater. A second trial was conducted with nine rootstock selections, all grafted to Cabernet Sauvignon and similarly exposed to 50 mM NaCl. Three measurement time points showed a delineation in photosynthetic response early in the latter trial. However, the observed differences were no longer significant following 21 days of exposure. These trials quantify the response of different Vitis spp. rootstocks under varying NaCl concentrations. More importantly, they explore the potential for translating salt-tolerant qualities of rootstocks to grafted scions in field conditions.

Funding Support: California Grape Rootstock Improvement Commission