Researchers compared different types of rice plants with different panicle shapes to understand why some varieties have better grain quality. They found that the position of the grain on the panicle affects its weight and seed setting rate. Generally, grains at the top of the panicle are heavier and have higher seed setting rates than those at the bottom. Primary branches have heavier grains than secondary branches. Grains at the top of the panicle are heavier in erect panicle varieties compared to curved panicle varieties.