Landry Rossdeutsch,* Paul Schreiner, Patricia Skinkis, Joseph Orton, and Laurent Deluc
*Oregon State University, Oregon State University, 4017 Agriculture and Life Sciences Bldg, Department of Horticulture, Corvallis, OR 97331 (landry.rossdeutsch@oregonstate.edu)
The scion growth potential (vigor) of grafted grapevines results from the three-way interaction between environment, scion genotype, and rootstock genotype. Since nitrogen (N) availability is a major driver of grapevine growth, understanding N regulation in scion and rootstock will lead to new insights to control canopy size in vineyards. We are developing a model system to study N regulation by evaluating the N supply responses of 12 scion-rootstock combinations with known differences in scion and rootstock vigor. Our primary objectives are to understand the influence of scions and rootstocks on growth parameters and resource allocation and to evaluate the role of N uptake regulation in scion growth response. To address the first objective, we measured components of vine water relations and gas exchange, plant biomass, carbon (C), and N allocation in four plants tissues (leaves, stem, trunk, and roots). Preliminary results supported the expected vigor behavior of the three Pinot noir scions used in this experiment, but this was not true for the four rootstocks examined. N availability altered C and N allocation in all tissues, but scion vigor was not affected. The N requirement for one-year old vines was satisfied by our lowest N rate and the experiment will be repeated under greater N limitation. However, this first trial will allow us to study the role of C and N reserves on scion vigor during the second growing season. We are addressing the second objective by comparing N uptake and N transport between two rootstocks using 15NO3. Several experiments are underway to compare N uptake kinetics over a range of N concentrations and N transport rate in response to plant N status. These analyses will be complemented with gene expression studies targeting N transport and signaling in roots and leaves.

Funding Support: OWRI Fermentation Initiative