Many farming operations aim at controlling the leaf area of the vine according to its load. There are several techniques, direct and indirect, of estimate of this leaf area in a specific way, but impossible to implement at great scales. These last years, research in airborne and satellite remote sensing made it possible to show that a multispectral index of vegetation, computed from measurements of reflectances (red and near infrared), the « Normalised Difference Vegetation Index » (NDVI), is well correlated to the « Leaf Area Index » (leaf area per unit of ground) of the vine. Nevertheless these methods of acquisition and processing data are rather constraining and complex.
Recently, N-Tech Industries in collaboration with Oklahoma State University developed a ground sensing apparatus, the GreenSeekerTM, which measures the NDVI.
In this study, the GreenSeekerTM, active sensor, is shown to function independently of the climatic conditions when it is used with a screen. The NDVI delivered by the GreenSeekerTM is mainly sensitive to the variations of porosity of the foliage. However, it can be used to carry out a follow-up of the foliar growth of the vine, but with much of precautions. Linked to a GPS, it makes it ple to chart relative variations of vigor at an intraplot level.
Authors: J.P. GOUTOULY (1), R. DRISSI (1), D. FORGET (2) and J.P. GAUDILLÈRE (1)
(1) INRA, UMR Œnologie-Ampélologie Équipe Écophysiologie and Agronomie Viticole
71, avenue Edouard-Bourlaux B.P.81, 33883 Villenave d’Ornon cedex, France
(2) INRA, Domaine expérimental viticole de Couhins, 33883 Villenave d’Ornon cedex, France
Keywords: Vitis vinifera, remote sensing, GreenSeekerTM, NDVI / LAI