Ideal nitrogen concentration in leaves for the production of high-quality grapes cv ‘Alicante Bouschet’ (Vitis vinifera L.) subjected to modes of application and nitrogen doses

Abstract

The low N use efficiency of vines calls for more efficient fertilization processes, which must mitigate losses caused by volatilization. Thus, N dose applications through different methods, such as fertigation, can potentiate N harnessing by vines. The study aimed to determine ideal N concentration in leaves for the production of high-quality grapes cv ‘Alicante Bouschet’ (Vitis vinifera L.) subjected to modes of application and N doses. The experiment was carried out in a bifactorial arrangement (N dose x modes of application) in a vineyard implanted in 2011, in Southern Brazil. The N doses were 0, 20, 40, 60, 80, and 100 kg N ha−1 year−1. The modes of application were N application without irrigation (NAWI), N application followed by irrigation (NAFI), and N application via fertigation (Fert). The study lasted three crop seasons. Complete leaves were collected at flowering and veraison to determine total N concentration. Grape yield and yield components were determined. Total soluble solids, total anthocyanins, and total polyphenols in grape must be assessed. The maximal recovery rate in grapes was at 36 kg N ha−1, when N concentration was higher than 2.75 % in leaves at flowering, and higher than 2.25 % at veraison, regardless of the N application mode. The concentrations of total anthocyanins, total polyphenols, and total soluble solids in grape must have diminished at doses higher than 60 kg N ha−1. Thus, N concentration in leaves can be used as a reference for grape yield, the concentration of anthocyanins, and soluble solids as indicators of high-quality grape.