Resumo

GALINDEZ-JAMIOY, Carlos A.. Nitrogen nutritional classification of sugarcane crops by wavelet synthetization of canopy hyperspectral data. Ing. compet. [online]. 2022, vol.24, n.1, e22311211.  Epub 30-Out-2021. ISSN 0123-3033.  https://doi.org/10.25100/iyc.24i1.11211.

Reflectance optical spectra of sugarcane canopy are analyzed by means of a continuous wavelet transformation (CWT), using the Ricker function as the mother wavelet transform, which represents the absorption due to physiological characteristics as the content of water, nutrients, or chlorophyll. The spectra correspond to four nitrogen levels, which represent different fertilization states, leaving the other variables such as irrigation, fertilizer source, season, and application method as constants. Each spectrum was grouped by fertilization level, to analyze the wavelet spectrogram of each one. As a result of this CWT analysis, it was obtained that the dyadic 8th scale shows relevant information on the absorption of the sugarcane crop at the wavelength of 760 nm, a wavelength previously reported in the literature as a variable that shows a high correlation with the nitrogenization of the sugar cane plant. The results of the wavelet analysis, at the wavelength of 760 nm ( 0.6nm, show that by means of the maximum absorption data, the crop can be classified to know whether it is or not within a region of optimal fertilization (with four sigmas). Similarly, this study shows a correlation of R2 = 0.91 between the information of the maximum wavelet power, analyzing the -8 scale, with the level of nitrogen fertilization of a sugarcane crop.

Palavras-chave : canopy; continuous wavelet transform; nitrogen fertilization; optical spectroscopy; Ricker function; sugarcane crop.

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