Biostimulation to Tempranillo grapevines (Vitis vinifera L.) through a brown seaweed during two seasons: Effects on grape juice and wine nitrogen compounds

Abstract There is little available information about the effects of seaweed biostimulation to grapevines on grape juice and wine nitrogen content. This trial aimed to study the effects of the biostimulation through an Ascophyllum nodosum fertilizer to Tempranillo grapevines at low (Ld: 0.25 % v v−1) and high (Hd: 0.50 % v v−1) dosages on must and wine amino acids and ammonium during two seasons. The content of these compounds in musts and wines were measured by UHPLC. The results showed that precipitations could have affected berry size and enological parameters of musts and wines. In the driest season (2017), Ld treatment increased the concentration of several amino acids in musts such as His, Arg, Ala, Gaba, Pro, Val, Met, Ile, Trp, Orn, Lys, and total amino acids. In the rainiest season (2018), the Hd treatment was the most effective, increasing the content of His, Cit + Thr, and Trp. Generally, a high yeast assimilable nitrogen (> 279.4 mg N L-1) content in the must allowed to reach a high concentration of amino acids in wines. Therefore, seaweed foliar application to grapevines allowed to improve amino acid content in musts in both seasons and its effectiveness depended of climate conditions of the season and the dosage applied.