The researchers studied how shading time and nitrogen levels affect the growth and quality of rice grains. They found that shading before heading reduced grain yield due to shorter panicles and fewer grains. Shading after heading also decreased yield because of lighter grains. However, high nitrogen levels helped offset these effects and increased grain yield. The time it took for grains to reach full weight was shorter with shading before heading, but longer with shading after heading. Overall, high nitrogen levels improved milling quality but reduced eating and cooking quality.