The researchers studied how to improve the quality of high-yielding japonica rice in Northeast China. They used a breeding method that combines different types of rice to create new varieties. By analyzing the genetic factors of these new rice lines, they found that certain genes affect traits like amylose content and protein content. They also discovered that a gene related to grain width and the introduction of genes from another type of rice impact the width of milled rice. To maintain good head rice rate, they suggest lowering the introduction of genes from the other type of rice during breeding. This study provides insights into improving the quality of rice in this region.