Nitrogen fertilization of Cabernet Sauvignon grapevines: yield, total nitrogen content in the leaves and must composition

English. Grapevines grown on sandy soils are subjected to the application of supplemental nitrogen (N); however, there is little information available regarding the impact of these applications on yield, plant nutritional state and must composition. The aim of this study was to evaluate the yield, nutritional state and must composition of grapevines subjected to N fertilization. Cabernet Sauvignon grapevines were subjected to annual applications of 0, 10, 15, 20, 40, 80 and 120 kg N ha-1 in 2008, 2009 and 2010. During the 2008/09, 2009/10 and 2010/11 harvest seasons, leaves were collected during full flowering and when the berries changed color, and the total N content was analyzed. The grape yield and the enological characteristics of the must were evaluated. The response to applied N was low, and the highest Cabernet Sauvignon grape yield was obtained in response to an application of 20 kg N ha-1year-1. The application of N increased the nutrient content in the leaf collected at full flowering, but it had little effect on the total nutrient content in the must, and it did not affect the enological characteristics of the must, such as soluble solids, pH, total acidity, malic acid and tartaric acid.

Portuguese. As videiras cultivadas em solos arenosos são submetidas a aplicações de nitrogênio (N), porém são poucas as informações sobre o seu impacto na produção, estado nutricional e a composição do mosto. O trabalho objetivou avaliar a produção, estado nutricional e composição do mosto em videiras submetidas à aplicação de N. Videiras Cabernet Sauvignon foram submetidas à aplicação anual de 0, 10, 15, 20, 40, 80 e 120 kg N ha-1, em 2008, 2009 e 2010. Nas safras de 2008/09, 2009/10 e 2010/11 foram coletadas folhas no pleno florescimento e na mudança da cor das bagas, e analisado o teor de N total, avaliada a produção de uva e no mosto foram determinados atributos enológicos. A resposta à aplicação de N foi pouco expressiva, tanto que a maior produção de uva de Cabernet Sauvignon foi obtida com a aplicação de 20 kg de N ha-1 ano-1. A aplicação de N aumentou o teor do nutriente na folha coletada no pleno florescimento, mas pouco afetou o teor de nutrientes totais no mosto e não interferiu os atributos enológicos do mosto, como os sólidos solúveis, pH, acidez total e ácido málico e tartárico.