Improving the UAV-based yield estimation of paddy rice by using the solar radiation of geostationary satellite Himawari-8

Abstract

The objectives of this study were to improve the yield estimation of paddy rice based on the unmanned aerial vehicle remote sensing (UAV-RS) and solar radiation data sets. The study used the UAV-RS-based normalized difference vegetation index (NDVI) at the heading stage, the solar radiation data of geostationary satellite Himawari-8 and the solar radiation data of polar orbiting satellite Aqua/ MODIS. A comparison of two satellite-based solar radiation data sets (Himawari-8 and MODIS PAR) showed that the coefficient of determination (R 2 ) of estimated yield based on Himawari-8 solar radiation was 0.7606 while the R 2 of estimated yield based on the MODIS PAR was 0.4749. Additionally, the root mean square error (RMSE) of Himawari-8 solar radiation was 26.5 g/m 2 while the RMSE of estimated yield based on the MODIS PAR was 39.2 g/m 2 (The average observed yield was 489.3 g/m 2 ). The Estimated yield based on Himawari-8 solar radiation, therefore, outperformed the MODIS PAR-based estimated yield. The improvement of the temporal resolution of the satellite-based dataset allowed by using the Himawari-8 data set contributed to the improvement of estimation accuracy. Satellite-based solar radiation data allow yield estimation based on remote sensing in regions where there are no ground observation data of solar radiation.

Examination of appropriate observation time and correction of vegetation index for drone-based crop monitoring

“…July 22 nd between the panicle formation stage and the heading stage was an important time for observing paddy rice growth and using the results to adjust fertilization regimes. August 5 th heading stage was important for estimating the yield or protein content of brown rice by using the drone-based observation data Hama et al, 2020a;2020b . We developed a correction formula by using the data obtained on July 22 nd , and verified the formula using the data from both July 22 nd and August 5 th . The weather on July 22 nd was clear with occasional clouds, and was generally clear on August 5 th .…”