Leaf chlorophyll concentration can now be sampled non-destructively with commercially available sensors. One such sensor, the CM-1000, uses reflectance measurements in the visible and near infrared to estimate leaf chlorophyll concentration. In perennial crops such as tree fruit, these sensors may be used to assess the nutrient status of individual plants (e.g., trees) and allow for monitoring both spatially and temporally. A related tool for assessing leaf chlorophyll concentration at the canopy scale is remote sensing. Ideally, the remote sensing measurements could be used to spatially interpolate the individual plant measurements made with the handheld sensors. In this paper we evaluate concurrent CM-1000 and reflectance spectrometer measurements within a nitrogen trial on apple (Malus domestica Bork.) to address two questions. First, how well do measurements from handheld chlorophyll meters compare with NDVI and other indices from remote sensing? Second, do narrow band indices such as RVSI and MCARI offer additional sensitivity to nitrogen availability over the standard broad band indices such as NDVI? These questions are addressed through established (3rd year) small plot N fertilizer trials conducted in a commercial Fuji apple orchard.
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