Contribuicao para o estudo da fertilizacao da vinha: influencia da fertilizacao azotada, fosfatada e potassica na producao e na qualidade dos mostos da casta loureiro na regiao demarcada dos vinhos verdes

A study was performed, in the Portuguese Demarcated Region of Green Wine, to evaluate the influence of nitrogen, phosphorus, and potassium fertilization on the yield, must quality, plant vigour and blades and petioles macro nutrient concentrations of grapevine (Vitis vinifera L.), c v. Loureiro. The study was based on a long-term fertilizer trial arranged into complete randomized blocks with three replications. The experimental treatments consisted of twelve of the all possible combinations of a factorial experiment with three factors (N, P, and K) at four levels each. From 1992/93 to 1995/96, in each experimental plot, total grape yield, and plant vigour were evaluated. Samples of the basal cluster opposite leaf were collected annually, at 35 days after full bloom, and both blades and petioles concentrations of N, P, K, Ca and Mg were determined. Experimental results show that neither yield nor plant vigour were affected by nitrogen, phosphorus and potassium fertilization. Conversely, must ph decreased and malic and tartaric acid levels were increased by increasing nitrogen fertilization. Must total acidity decreased with applied potassium. Also, nitrogen fertilization decreased K and increased Mg concentrations in both blades and petioles; Regarding the last two nutrients, an opposite effect was found with potassium and phosphorus fertilizationAvailable from Fundacao para a Ciencia e a Tecnologia, Servico de Informacao e Documentacao, Av. D. Carlos I, 126, 1249-074 Lisboa, Portugal / FCT - Fundação para o Ciência e a TecnologiaSIGLEPTPortuga