ABSTRACT
Information on nitrogen fertilization in growing vines is still a very limited subject, especially for crops on sandy soils in the Pampa Biome in Rio Grande do Sul, where viticulture has expanded considerably in the last decade. This study aimed to assess the impact of N doses on growth of young plants of Chardonnay and Pinot Noir vines and N forms present in sandy soil in the Pampa Biome. The experiment was conducted from October 2011 to December 2012 in a vineyard in Santana do Livramento, in Southern Rio Grande do Sul State, in soil with 82 g kg-1 clay in the 0-20 cm layer. Vines of Chardonnay and Pinot Noir varieties were subjected to applications of 0, 10, 20, 40, 60, and 80 kg N ha-1 year-1. Total N in leaves, SPAD readings, stem diameter, plant height, and dry matter of the pruned material were evaluated in two growth cycles and three times. Soil samples were collected at 0-10 and 10-20 cm depths at four crop growth stages, in which N-NH4 +, N-NO3 -, and total N were analyzed and the mineral N was calculated. The N levels applied to young vines, although they did not provide relevant changes in the N-NH4 +, N-NO3 -, and mineral N contents in the soil, were able to increase the N content in the leaves, increasing plant vigor. because the reason is that there was an increase in stem diameter, plant height, and dry matter of pruned material in most evaluation periods. These parameters suggest better growth patterns and uniformity of young grapevines with possible positive effects in anticipation of production, demonstrating the importance of nitrogen fertilization strategies to the growing vines in the sandy soil conditions of the Pampa Biome.
Key words:
nitrogen; leaf analysis; SPAD-520; Vitis vinifera