title: Relationship between hyperspectral indices, agronomic parameters and phenolic composition of Vitis vinifera cv Tempranillo grapes.
abstract: 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.
  
  
  CONCLUSIONS
  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. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
authors.affiliation: Grupo de Investigación en Polifenoles, Unidad de Nutrición y Bromatología, Facultad de Farmacia, University of Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.
authors.forename: Ignacio
authors.identifier: http://orcid.org/0000-0001-8794-8328
authors.initials: I
authors.lastname: García-Estévez
authors.affiliation: Grupo de Investigación en Polifenoles, Unidad de Nutrición y Bromatología, Facultad de Farmacia, University of Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Quijada-Morín
authors.affiliation: Grupo de Investigación en Polifenoles, Unidad de Nutrición y Bromatología, Facultad de Farmacia, University of Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.
authors.forename: Julián C
authors.initials: JC
authors.lastname: Rivas-Gonzalo
authors.affiliation: Instituto Hispano Luso de Investigaciones Agrarias, CIALE. University of Salamanca, Villamayor, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Martínez-Fernández
authors.affiliation: Instituto Hispano Luso de Investigaciones Agrarias, CIALE. University of Salamanca, Villamayor, Spain.
authors.forename: Nilda
authors.initials: N
authors.lastname: Sánchez
authors.affiliation: Instituto Hispano Luso de Investigaciones Agrarias, CIALE. University of Salamanca, Villamayor, Spain.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: Herrero-Jiménez
authors.affiliation: Grupo de Investigación en Polifenoles, Unidad de Nutrición y Bromatología, Facultad de Farmacia, University of Salamanca, Campus Miguel de Unamuno, Salamanca, Spain.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Escribano-Bailón
mesh_terms: D000383:Agriculture; D005638:Fruit / Q000737:chemistry / Q000254:growth & development; D010636:Phenols / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D027843:Vitis / Q000737:chemistry* / Q000254:growth & development
chemical_list: D010636:Phenols; D010936:Plant Extracts; D012987:Soil
keywords: Tempranillo grapes; hyperspectral indices; phenolic composition; principal component regression; water status