Submitted to: American Society of Horticulture Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/22/2001
Publication Date: N/A
Technical Abstract: During wine grape production, fruit and wine quality are affected by the amount of nitrogen (N) applied to the vines during the growing season. However optimum rates and timing of N fertilization for premium wine grapes are generally unknown. We examined the effect of applying three different rates of N fertilizers at pre-bloom and at early veraison to Vitis vinifera L. cv. Cabernet Sauvignon (FPMS Clone 8) on Freedom rootstock grown in Linden, CA. All vines were fertigated with 7.8 kg N ha-1 added as CAN-17 at bud break. At pre-bloom, vines were fertigated with 7.8 kg N ha-1 added as 15-4-4, plus 0 (treatment 1), 5.8 (treatment 2), or 11.5 (treatment 3) kg N ha-1 added as UN32. During early veraison, vines were fertigated with 3.5 kg N ha-1 added as UN32.Over the entire growing season, treatment 1 received 15 kg N ha-1 added as UN32. Over the entire growing, treatment 2 received 22.5 kg N ha-1, and treatment 3 received 30 kg N ha-1. Fruit was collected from each treatment at harvest, juiced, and analyzed for N. Although N applications equaled or exceeded recommended levels of fertilizer in each treatment, total N (124.1 mg N liter-1) and arginine-N (63.0 mg N liter-1) content of the juice were deficient and not significantly different among fertilizer treatments. Vegetative growth of the vines, however, increased with the amount of N applied. This suggests that fruit N content at harvest may be more related to timing of fertilizer application rather than to the total amount of N applied.