Santosh Kalauni* and Paul Schreiner
*Oregon State University, Horticulture; College of Agricultural Science; 4017 Agriculture and Life Sciences Building; Corvallis, Corvallis, OR, 97331
(kalaunis@oregonstate.edu)

The supply of mineral nutrients is essential for optimal vine growth and fruit production. We studied the impact of nitrogen (N), potassium (K), and magnesium (Mg) fertilization on nutrient status, productivity, and fruit composition over two years in western Oregon vineyards. The N trial in Chardonnay used three rates of soil-applied N. The K trial, conducted in a K-deficient Pinot noir vineyard, had four treatments, three rates of soil-applied K and a single foliar treatment. A Mg trial in a Mg-deficient Pinot noir vineyard included three rates of foliar-applied Mg. Each treatment was replicated four times using a randomized block design at each vineyard. The Chardonnay trial showed that leaf blade and petiole N status at bloom and veraison were elevated to greater extent as the rate of N increased, although minor variations occurred among tissue and time. Yeast assimilable nitrogen in must increased with increasing rate of N in year 1, but was similar in year 2 at medium and high rates of N. Soil-applied K increased leaf blade and petiole K at bloom and veraison in Pinot noir in year 2, but foliar K applications did not. However, all three added K treatments increased K in woody canes at dormancy. In the Mg trial, both the low and high rates of Mg applied to the canopy elevated leaf blade Mg status by veraison and reduced the extent of Mg-deficient leaf symptoms developing in late summer, but petioles did not respond to Mg fertilization. In all three trials, neither vine size nor yield increased thus far by fertilizer additions. In addition, cluster size, berry size, and must maturity indices have yet to be altered by N, K, or Mg additions. It will be interesting to see if productivity, yield, or fruit composition will be altered in the future.

Funding Support: National Institute of Food and Agriculture-Specialty Crop Research Initiative