The researchers studied how to accurately measure leaf area in rice fields using remote sensing data. They found that existing methods worked well at the beginning of the crop growth, but were less accurate after the heading stage. This was because the presence of panicles changed the canopy structure and affected the measurements. By comparing different ways of measuring canopy reflectance, they developed a new method to remove the effects of panicles and improve the accuracy of leaf area measurements in rice fields after the heading stage.