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Submitted to: Northwest Center for Small Fruit Research Proceedings
Publication Type: Abstract Only Publication Acceptance Date: 10/14/2005 Publication Date: 12/1/2005 Citation: Schreiner, R.P. 2005. Identifying optimal nutrient concentrations for premium winegrape production based on physiological needs and fruit quality. Northwest Center for Small Fruit Research Proceedings. p.79-81. Interpretive Summary: Technical Abstract: The primary goal of this project is to develop better tissue nutrient standards for winegrape production based on fruit quality and physiological performance. 2005 was the third (and final) growing season of Pinot noir vines in our pot-n-pot, sand-culture vineyard in preparation for the experiment to manipulate N, P, and K supply in 2006 & 2007. Baseline data collected this year showed that vine growth under uniform complete nutrition was excellent (maybe a little excessive). Trunk cross sectional area increased 3-fold over last year. Leaf and petiole nutrient concentrations at bloom were comparable to typical bloom-time values for Pinot noir grown in Oregon, although copper was a little low. No nutrients were at excessively low or high concentrations, so our rate of nutrient supply this year (which will be the control rate next year) appears to appropriate. Measurements of water status of vines and the sand medium showed that vines were mildly water stressed prior to veraison as planned, but we had some difficulty achieving a consistent level of moderate water stress during the ripening period. This was due, in part, to rainfall and large daily changes in evapotranspiration during ripening. We identified the soil moisture content (6.7% in this system) at which vines shut down gas exchange and wilt, so that we can better control the level of intended water stress during ripening in 2006 & 2007. This information combined with daily reference evapotranspiration levels will be used to achieve consistent water stress levels. Our data showed that we cannot rely solely on leaf water potential measurements taken with the pressure bomb as our indicator of plant water stress, as stomatal closure was often observed in leaves that had relatively high leaf water potentials. |
