TY - JOUR T1 - Comparison of Different Vegetative Indices for Calibrating Proximal Canopy Sensors to Grapevine Pruning Weight JF - American Journal of Enology and Viticulture JO - Am J Enol Vitic. DO - 10.5344/ajev.2021.20042 SP - ajev.2021.20042 AU - James A. Taylor AU - Terence R. Bates Y1 - 2021/04/23 UR - http://www.ajevonline.org/content/early/2021/04/22/ajev.2021.20042.abstract N2 - Canopy sensing in viticulture is widely associated with the term NDVI (Normalized Differences Vegetation Index). However, there are many other vegetative indices that can be calculated from information captured with Visible-NIR sensors. A proximal canopy sensor was used to survey 27 vineyards in the Lake Erie Concord belt and pruning weights (PW) collected at a density of ~25 samples per vineyard. Seven vegetation indices (VIs) were derived from the sensor data and the first principal component (PC1) extracted from a principal components analysis of the seven VIs. The VIs and PC1 were regressed against the local PW measurements and ranked in terms of their goodness of fit. Over the 27 vineyards, there was no single VI that out-performed the others, although VIs that used the red-edge band had a slight advantage over VIs using the red band. It is therefore recommended to use the NDRE (Normalized Differences Red Edge index) in place of the NDVI when predicting PW from terrestrial-based proximal canopy surveys. The PC1 derived from the decomposition of all seven VIs did appear to convey some benefit to PW prediction compared with a single VI approach, particularly with just NDVI. More research into the potential for multivariate approaches is recommended. ER -