Monitoring of ripening and yield of vineyards in Nemea region using UAV

Abstract

Context and purpose of the study ‐ Nemea region is the largest POD zone in Greece. Agiorgitiko (Vitis vinifera L. cv.) is the most cultivated variety in Greece with significant wine potential. Due to the extension of the area there is a great variability of soil content and climatic conditions. Seven vineyards in the POD zone were selected and monitored for ripening evolution and yield of vine plots using UAV through the extraction of vegetation indices (NDVI, NDRE, GNDVI and OSAVI). Grapes were harvested at maturity and the enological potential was estimated. Winemaking was applied in order to evaluate the potential of each sub‐zone and in order to search if any connection with the vegetation indices. The aim of this study is to research the “terroir” impact in Agiorgitiko grapes and compare the quality features in order to split the Nemea region in subzones.

Material and methods ‐ Four flights took place during the summer of 2018. The UAV platform used was the DJI Matrice 100 and was equipped with the Parrot Sequoia camera. The collected images were combined into orthosmosaics and further analysis was made by combining these mosaics and extracting vegetation indices. From each vineyard grapes were sampled to be analyzed for their physicochemical properties (sugar content, total acidity, pH, YAN, color characteristics). Furthermore, grapes from each vineyard were harvested on the technological maturity level. The same vinification protocol was applied in all samples. After the alcoholic fermentation was conducted the wines were inoculated with lactic bacteria for malolactic fermentation. Classical analysis was performed in all samples.

Results ‐ Vegetation indices (NDVI, NDRE, GNDVI and OSAVI) showed significant differences in each vineyard. Also, significant differences were observed in grapes and wines originated from different vineyards. Phenolic and anthocyanin profile indicated a greater potential in wines from vineyards in higher altitude.