GROUND BASED HYPERSPECTRAL REMOTE SENSING FOR DISEASE DETECTION OF TOBACCO PLANTS

摘要

Greenhouse experiment was conducted in the Institute “N. Poushkarov”, Department Plant Protection Kostinbrod, with young tobacco plants infected with TSWV (Tomato Spotted Wilt Virus). Remote sensing technique, spectral reflectance, was applied for detecting and assessing the development of the viral infection. At growth stage 4-6 expanded leaf some of the plants were inoculated with TSWV by using infected material from a pepper fruit with severe symptoms of yellow spotting. Hyperspectral reflectance data of healthy (control) and infected leaves was collected by a portable fibre-optics spectrometer in the visible and near-infrared spectral ranges. The measurements were conducted on the 14th and 20th days after the inoculation. Spectral reflectanceanalyses were performed in green, red, red edge, and NIR regions. The differences between the reflectance spectra of control and infected leaves were assessed by means of the Student’s t-criterion at ten selected wavelengths and first derivative analysis. The viral concentration in the leaves was determined by the serological method DAS-ELISA. On the 14th day no visual changes in some of the infected leaves occurred but the differences of averaged reflectance spectra against the control were statistically significant at four of the investigated wavelengths and the presence of TSWV was established, i.e. the latent infection has been occurred. Reflectance spectra of the other leaves differed statistically signiflcantly at eight wavelengths. On the 20thday the statistical analysis indicates an increase of the number of statistically significant differences and the shift of the red edge position, i.e. the infection is deepening that is in agreement with serological analyses.