Relationship between X-band backscattering coefficients from high-resolution satellite SAR and biophysical variables in paddy rice

The objective of this study was to explore unique capabilities of X-band satellite synthetic aperture radar (SAR) sensors for the assessment of rice growth and yield. X-band SAR images were acquired by COSMO-SkyMed at spotlight mode during the maturing stage. Detailed plant biophysical and morphological measurements were made on the ground concurrently with the satellite SAR observations. The backscattering coefficients (sigma(0)) of rice canopies and water surfaces were consistent over two years. The sigma(0) values in rice canopies were higher than the water surfaces by 8 dB. Although the sigma(0) was poorly correlated with the volume-related canopy variables such as leaf area index (LAI), the X-band sigma(0) was best correlated with the panicle biomass among all biophysical variables. This is the first evidence suggesting the potential of satellite SAR image for the direct assessment of rice yield at regional scales.