EVALUATION OF AN INDIRECT METHOD FOR LEAF-AREA INDEX DETERMINATION INTHE VINEYARD - COMBINED EFFECTS OF CULTIVAR, YEAR AND TRAINING SYSTEM

The performance of the plant canopy analyzer LAI-2000 was evaluated in three seasons to estimate vineyard LAI (leafarea index) in the Bordea ux area. Measurements were made in a vertical-trellised vineyard with 5555 Semillon and Sauvignon blanc vines per ha, and with 2525 lyre-tra ined Cabernet franc vines per ha. Various LAI-2000 sampling protocols were tested and the data compared with destructive determinations. Whi le the results from single vines a ere not satisfactory, very good rel ationships were obtained if five consecutive vines were used. In the v ertical-trellised vineyard, a very accurate and direct estimate of LAI could be obtained with the LAI-2000 using a combination of ''parallel '' and ''diagonal'' sampling protocol. LAI values obtained by direct a nd LAI-2000 had a 1:1 correspondence and were identical for both, year and cultivar. For the lyre system, a local calibration was required, mainly because of the contribution of shoots, perennial vine parts and posts. This calibration was easily obtained by progressively removing leaves from the vines.