Authors: Panneton, Bernard¹; Guillaume, Serge²; Roger, Jean-Michel²; Samson, Guy³

Source: Applied Spectroscopy, Volume 64, Issue 1, Pages 6A-30A and 1-139, (January 2010) , pp. 30-36(7)

Publisher: Society for Applied Spectroscopy

Abstract:

Precision weeding by spot spraying in real time requires sensors to discriminate between weeds and crop without contact. Among the optical based solutions, the ultraviolet (UV) induced fluorescence of the plants appears as a promising alternative. In a first paper, the feasibility of discriminating between corn hybrids, monocotyledonous, and dicotyledonous weeds was demonstrated on the basis of the complete spectra. Some considerations about the different sources of fluorescence oriented the focus to the blue-green fluorescence (BGF) part, ignoring the chlorophyll fluorescence that is inherently more variable in time. This paper investigates the potential of performing weed/crop discrimination on the basis of several large spectral bands in the BGF area. A partial least squares discriminant analysis (PLS-DA) was performed on a set of 1908 spectra of corn and weed plants over 3 years and various growing conditions. The discrimination between monocotyledonous and dicotyledonous plants based on the blue-green fluorescence yielded robust models (classification error between 1.3 and 4.6% for between-year validation). On the basis of the analysis of the PLS-DA model, two large bands were chosen in the blue-green fluorescence zone (400-425 nm and 425-490 nm). A linear discriminant analysis based on the signal from these two bands also provided very robust inter-year results (classification error from 1.5% to 5.2%). The same selection process was applied to discriminate between monocotyledonous weeds and maize but yielded no robust models (up to 50% inter-year error). Further work will be required to solve this problem and provide a complete UV fluorescence based sensor for weed-maize discrimination.

Keywords: FLUORESCENCE SPECTROSCOPY; MONOCOTYLEDONOUS; DICOTYLEDONOUS; DISCRIMINATION; PLANT FLUORESCENCE; PARTIAL LEAST SQUARES; PLS; DISCRIMINANT ANALYSIS

Document Type: Research article

DOI: http://dx.doi.org/10.1366/000370210790572106

Affiliations: 1: Horticultural R&D Centre, Agriculture and Agri-Food Canada, St-Jean-sur-Richelieu, QC, Canada, J3B 3E6 2: Cemagref, UMR ITAP, 34196 Montpellier, France 3: Département de chimie-biologie, Université du Québec à Trois-Rivières, Trois-Rivières, QC, Canada, G9A 5H7

Publication date: 2010-01-01

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