HYPERSPECTRAL FIELD SPECTROMETRY FOR ESTIMATING GREENBUG (HOMOPTERA: APHIDIDAE) DAMAGE IN WHEAT

摘要

Remote sensing techniques have the potential to provide information about vegetation characteristics. Therefore, this study was designed to determine the ability of a hyperspectral field spectrometer along with a digital camera to estimate greenbug (Schizaphis graminum Rondani) damage to wheat (Triticum aestivum L.) in field condition. Percentage reflectance data and digital images were collected over 1 m~2 wheat plots in four fields in mid-May of 2005. Percentage reflectance data were transformed into spectral vegetation indices and a damage quantification software package was used to determine percentage damage in each of the digital images. The percentage damage was also visually assessed on the ground. A simple linear regression procedure was conducted to investigate the relationships between spectral vegetation indices and percentage damage obtained from the ground and digital images. The results show that there were strong relationships between percentage damage and a newly developed Damage Sensitive Spectral Index (DSSI_(1-3)). The coefficients of determination (R~2) were 0.77, 0.86, 0.92, and 0.95 for the percentage damage determined using the digital images and DSSI_(1-3) for fields 1-4, respectively. The relationships between the percentage damage collected on the ground and DSS_(I1-3) were 69%, 81%, 89%, and 92% for the fields 1-4, respectively. These results strongly suggest that percentage reflectance and digital image data can be used to estimate greenbug damage in wheat under field conditions with a high degree of accuracy and precision.