Nitrogen fertilization of ‘Chardonnay’ grapevines: yield, must composition and their relationship with temperature and rainfall

In soils rich in organic matter (OM), such as those in the elevations of South Brazil, the mineralized N from organic matter does not always meet the N demands of grapevines, thus, N applications are necessary during vine growth. However, the optimal N rate to achieve satisfactory yield and desirable grape enological composition is not known. The study aimed to evaluate yield and must composition of grapevine subjected to N applications, in relation to temperature and rainfall. The experiment was conducted in a vineyard planted in 2003 in the city of Água Doce, located in the Midwest region of the state of Santa Catarina, southern Brazil. The cultivar ‘Chardonnay’ grafted on rootstock 1103 Paulsen, planted in clay, high-OM soil was trained as a spur pruned cordon system. From 2011 to 2014, the grapevines were submitted to the application of N as urea at the following rates: 0, 20, 40, 80 and 120 kg N ha-1 split at bud sprout and full bloom. Leaves, collected at flowering and veraison, were dried, milled and analyzed for total N. At harvest, the number of clusters per plant and yield were recorded. Total soluble solids, titratable acidity, pH and tartaric acid were evaluated on must. Temperature and rainfall data were collected throughout the experiment. The application of N increased N concentration in leaves but had little effect on yield and must composition. According to principal component analysis, a negative correlation between rainfall and N in must was found. The highest N concentration in must was observed in crop season 2011/2012 with low rainfall; the opposite occurred in 2013/2014.