[EN] BACKGROUND: The phenolic composition of grapes is key when making decisions about harvest date and ensuring the quality of grapes. The present study aimed to investigate the relationship between the detailed phenolic composition of grapes and the agronomic parameters and hyperspectral indices, with the latter being measured via field radiometry techniques.
RESULTS: Good correlations were found between phenolic composition (both anthocyanin and flavanol composition) and some
hyperspectral indices related to vigor, such as the NDVI (normalized difference vegetation index) and the SAVI (soil adjusted
vegetation index). The strongest correlations were observed between the phenolic composition of grape skin at harvest time
and variables measured from grapes at veraison time, as well as variables determined from grapevines at harvest time. The
potential usefulness of these hyperspectral indices calculated from measurements performed directly on grapes or grapevines
for estimating the anthocyanin and flavanol composition of grape skins was indicated by the high coefficients of determination
(R2 = 0.7955 and R2 = 0.8594, respectively) as obtained by means of principal component regression.
CONCLUSION: According to the results of the present study, hyperspectral indices calculated from measurements performed
directly on grapes at veraison time or on grapevines at harvest time may be useful for estimating the anthocyanin and flavanol
composition of grape skins. This suggests that field radiometry might provide valuable information for estimating the phenolic
composition of grapes, which may prove to be very useful when establishing strategies for harvest planning.
