Identification of Aphid Infestation in Mustard by Hyperspectral Remote Sensing

Abstract

Spectral reflectance was taken in healthy as well as aphid infested canopies of mustard in field as well as in the laboratory. The spectral reflectance of aphid infested canopy and healthy canopy taken in the laboratory had significant difference in NIR region. In the visible region, the reflectance peak occurred in healthy canopy at around 550-560 nm while this peak was lower by 31% in the aphid infested canopy. The reflectance for healthy crop was found to be more in visible as well as NIR region as compared to aphid infested canopy. The most significant spectral bands for the aphid infestation in mustard are in visible (550-560nm), and near infrared regions (700-1250 nm and 1950-2450 nm). The different level of aphid infestation can be identified in 1950-2450 nm spectral regions. Spectral reflectance of the mustard canopy for different varieties had significant difference in the reflectance at different phenological stages in NIR (720-1360 nm) region. Also the peak at 550-560 nm in the visible region was lower at maturity stages as compared to vegetative, flowering and pod formation stages. Spectral indices viz NDVI, RVI, AI and SIPI had significant correlation with aphid infestation. Hence these indices could be used for identifying aphid infestation in mustard