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A Comparison of Two Techniques for Nondestructive Measurement of Chlorophyll Content in Grapevine Leaves

^a Center for Advanced Land Management Information Technologies (CALMIT), School of Natural Resources, Univ. of Nebraska-Lincoln, Lincoln, NE 68583-0517
^b Agricultural Research and Development Center, Univ. of Nebraska-Lincoln, Ithaca, NE 68033-2234
^c Center for Advanced Land Management Information Technologies (CALMIT), School of Natural Resources, Univ. of Nebraska-Lincoln, Lincoln, NE 68583-0517

View larger version (15K): [in this window] [in a new window]   Fig. 1. Relationships of the SPAD readings (left y axis) and Red Edge Chlorophyll Index (CIred edge) (right y axis) versus the laboratory-determined chlorophyll content for the 20 Edelweiss leaves.

View larger version (12K): [in this window] [in a new window]   Fig. 2. Noise equivalent of chlorophyll estimation by SPAD and Red Edge Chlorophyll Index (CIred edge) plotted vs. Chl content. As chlorophyll <300 mg/m2 (yellowish to green leaves), noise equivalent of SPAD was slightly less than noise equivalent of CIred edge. When chlorophyll >300 mg/m2, noise equivalent of SPAD increases drastically indicating sharp decrease in accuracy of estimation of moderate-to-high chlorophyll content by SPAD. Noise equivalent of CIred edge remained constant in a wide range of chlorophyll variation.

View larger version (21K): [in this window] [in a new window]   Fig. 3. Comparison of Minolta SPAD-502 chlorophyll meter readings with chlorophyll content derived from Eq. [5] with measured reflectance for 288 Edelweiss grapevine leaves. (A) Chlorophyll contents ranged from 63 to 576 mg/m2: 288 yellowish to dark green leaves; (B) Chlorophyll exceeded 300 mg/m2: 148 green to dark green leaves.