Remote Sensing Study of the Influence of Herbicides Fluridone and Acifluorfen on the Spectral Reflectance of Pea Plant Leaves (Pisum sativum L.)

Results from a remote sensing study of the leave spectral reflectance of pea plants (Pisum sativum L. cultivar Scinado) treated by the photosynthetic herbicides fluridone and acifiuorfen are presented. According to the mode of action, fluridone belongs to Fl (photobleaching) group of herbicides, and acifiuorfen -to the group E as classified by the Herbicide Resistance Action Committee. The pea plants were grown hydroponically in a growth chamber in a nutritious medium to which the herbicides were added at two low concentrations (1 muM, 0.1 muM for fluridone, and 25 muM, 2.5 muM for acifiuorfen). The high-resolution spectral data were obtained in the visible and near infrared ranges of the spectrum (450/850 nm) using a USB2000 fiber optic spectrometer at a spectral resolution (halfwidth) of 1.5 nm. After data analysis, optimal spectral intervals for evaluation of the herbicide action were specified. The changes occurring in the spectral reflectance of the pea plants were assessed in four intervals: 520/580 nm (region of maximal reflectivity of green vegetation), 640/680 nm (region of maximal leave absorption), 690/720 nm (red edge region), and 720/770 nm (near infrared region) using the t-criterion of Student and linear discriminant analysis. Statistically significant differences were found between the spectral reflectance data of leaves of control and treated with herbicides plants at a significance level p<0.05 for the two fluridone concentrations and for 25 muM concentration of acifiuorfen. The applied approach provides fast and reliable remote sensing of plant response to the environment.