Many species of rice can be found in the northern sector of Quang Ninh. Excellent species are developing rapidly but many bad species still exist. Many species have been cultivated for many years but due to lack of care and selection some of them are undergoing mixing and regression. The increasingly poor seeds have given unstable yields. Therefore, it is important to select excellent seeds that will give high and stable yields.
Trans. of Khoa Hoc Ky Thuat Nong Nghiep (North Vietnam) p592-594 Oct, 1964.