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Nondestructive Measurement of Grapevine Leaf Area by Ground Normalized Difference Vegetation Index

^a ECAV, UMR EGFV, Institut des Sciences de la Vigne et du Vin de Bordeaux, Domaine INRA de la Grande Ferrade, BP 81, 33883 Villenave d'Ornon Cedex, France
^b Chateau Couhins, Chemin de la Gravette, BP 81, 33883 Villenave d'Ornon Cedex, France

View larger version (21K): [in this window] [in a new window]   Fig. 1. Schematic protocol to collect normalized difference vegetation index (NDVI) and vertical leaf area index (VLAI) measurements in Exp. 2 and 3. The VLAI is estimated on the leaves present in each of the 10 0.2 by 0.61 m rectangular areas. For the same area NDVI measurements are performed each centimeter: for this size area NDVI is averaged on 20 measurements. L: low canopy area scanned by the GreenSeeker; M: medium area scanned by the GreenSeeker; H: high canopy area scanned by the GreenSeeker.

View larger version (9K): [in this window] [in a new window]   Fig. 2. Relationship between normalized difference vegetation index (NDVI) and measured gap fraction per 0.01 by 0.61 m rectangular area, using a single layer of vine leaves (young in white, older in black).

View larger version (17K): [in this window] [in a new window]   Fig. 3. (A) Relationship between mean normalized difference vegetation index (NDVI) and measured gap fraction per 0.2 by 0.61 m rectangular area. (B) Relationship between mean NDVI and measured vertical leaf area index (VLAI) per 0.2 by 0.61 m rectangular area.

View larger version (11K): [in this window] [in a new window]   Fig. 4. Relationship between mean normalized difference vegetation index (NDVI) and measured vertical leaf area index (VLAI) per 1 by 0.61 m rectangular area, including all the data collected from 12 May to 12 July 2004 corresponding to the lower part of the canopy.

View larger version (72K): [in this window] [in a new window]   Fig. 5. Three normalized difference vegetation index (NDVI) maps (2004) of plot 2 obtained by Ordinary Kriging. The name of each map (L, M, and H) refers to the strip scanned with the GreenSeeker as indicated in Fig. 1. The NDVI measurements were performed every row (North-South oriented). Lower vigor areas (white encircled, L map) and high vigor (black encircled, M map) are both found when measuring the medium part of the canopy (M map), as representative of the whole.

View larger version (112K): [in this window] [in a new window]   Fig. 6. Plot 2 normalized difference vegetation index (NDVI) and pruning weight maps obtained by ordinary Kriging. Pruning weight map is based on mean pruning weight of 96 experimental plots, whereas NDVI maps are based on continuous measurements in each row.

View larger version (92K): [in this window] [in a new window]   Fig. 7. Plot 3 normalized difference vegetation index (NDVI) map (June 2005). This plot showed two areas of distinct vigor, and was thus segmented in two (dotted line) for maturing controls (results in Table 1). The vertical line segments represent the vine rows.