Non-invasive real-time monitoring of vineyard soils, berries and leaves with FT-NIR spectroscopy

Production of high quality wines requires a permanent monitoring during the entire winemaking process. A healthy production, ensured by tailor-made strategies that will lead to consumer's satisfaction is of the utmost importance. The influence of the terroir characteristics on the features of a wine has always been prone to much debate amongst the wine industry. The composition of grapes is the result of the characteristics of each individual terroir. Soil impact on growth of the vineyard, grape variety characteristics and ultimately wine quality is well known. Current strategy for analysing soils (pedology) is based on wet chemistry methods, which are often laborious, expensive, time-consuming and may be of limited use. An efficient, high-throughput analytical method for estimating the impact of soil quality, tillage and thinning on the grapes quality is of paramount importance for the wine industry. Near infrared spectroscopy (NIRS) is a rapid, non-destructive, inexpensive and accurate analysis technique and its use in soil evaluation for discriminating different types of soil as well as soil constituents is rapidly increasing. Results obtained from direct monitoring of four Portuguese vineyards in different locations (wine appellation regions “Alentejo”, “Dão”, “Douro” and “Vinhos Verdes”) using two different portable near-infrared spectrometers are presented. In-situ measurements of soils (at different depths), plant leaves and berries were performed on different stages of the ripening period. Spectral analysis was performed with chemometric methods: PCA and PLS-DA. This monitoring approach revealed to be an excellent tool for the support of a vineyard's micro-zoning process.