Since 1964, Yuan Longping has been studying hybrid rice. In 1973, he realized three-line matching. In 1974, he bred the first hybrid rice combination Nanyou No. 2. In 1975, he successfully developed hybrid rice planting technology. It laid the foundation for the large-scale promotion of hybrid rice. Yuan Longping's hybrid rice research was groundbreaking in China, but it was not the first in the world. In 1965, Shinjo Nagatomo in Japan obtained a three-line package of japonica rice, but it was not used for production. .