Effect of vegetal protein hydrolysate on ripening and berry quality in viticulture

Protein hydrolysates are an important group of plant biostimulants based on a mixture of peptides and amino acids; they are mainly obtained by enzimatic and/or chemical hydrolyses of proteins from vegetal derived raw materials. The research deals with the effects of vegetal protein hydrolysate supplied by foliar application on grapevine ecophysiological, vegetative and productive characteristics, to improve yield and quality in case of abiotic stress conditions. This study was carried out in Tuscany (Italy) in the heart of Chianti production area on a Sangiovese vineyard. The main problem of this area is the high sugar content at harvest and a low polyphenols content: the goal of this research is to separate the technological maturation from phenolic one. The product was sprayed on canopies during the 2016 growing season to enhance production, preserving the quality and promote an early balanced maturation, in terms of sugar content and color (accumulation of anthocyanins). Measurements of leaf gas exchange, chlorophyll content and leaf water potential, were carried out. Yet, from veraison to harvest, berry samples were collected for analysis of soluble solids (°Brix), titratable acidity (g/L of tartaric acid), pH, and berry weight (g), potential content of anthocyanins and total and extractable polyphenols (mg/L). The treatment increased photosynthesis and transpiration in the hottest period of the season. Moreover, the results show a good balance between polyphenols , anthocyanins and sugar content in grapes, already one week before harvest. This result assumes an important meaning especially to preserve both environment and berry quality.