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Remote-Sensing Measures of Cotton Maturity – Cutout and Boll Opening

F. Aubrey Harris, Patrick J. English, Donald L. Sudbrink, Steve P. Nichols, Charles E. Snipes, Gene Wills, and James Hanks


Imagery data were used in 2001 to classify a cotton field into two zones based on COTMAN spray termination rules. NDVI (Normalized Difference Vegetation Index) was used to classify portions of the field to spray (NAWF = 5 + <350 HU) or no spray (NAWF = 5 + > 350 HU) where NAWF = Node Above first position White Flower. Replicated experiments with planting date and cotton variety treatments were conducted in 2002 and 2003 to determine if radiometry data and/or multi-spectral imagery data could be used to estimate time of cutout (NAWF = 5) in a cotton crop. This report focuses on radiometry data acquired with a GER 1500® spectroradiometer. Reflectance data were used to calculate percent reflectance from which various indices were calculated and analyzed for correlation to NAWF and percent open bolls. The widely used NDVI was not closely correlated to NAWF or percent open bolls. Two other indices, VARI (Visible Atmospherically Resistant Index) and GVI (Green Vegetation Index), were closely correlated to the maturity parameters, especially for 2002 data.

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Document last modified 04/27/04