Evolution and development of five generations of rice

In recent one hundred years, rice (Oryza sativa L.) varieties have undergone constant upgrading with the development of modern rice farming. According to the genetic basis, characteristics and evolution of rice varieties, this paper divides rice varieties into five generations (G). The first generation (1G) is tall rice, the second generation (2G) is semi-dwarf rice, the third generation (3G) is intra-subspecific hybrid rice, the fourth generation (4G) is inter-subspecific introgression rice, and the fifth generation (5G) is inter-subspecific hybrid rice. In five generations of rice, 1G of tall rice was replaced by semi-dwarf rice after the 1960s, and no more popularly planted afterwards. 2G of semi-dwarf rice, 3G of intra-subspecific hybrid rice, and 4G of inter-subspecific introgression rice are still being used today. 5G of inter-subspecific hybrid rice is coming to be applied. The emergence of each generation of rice is a major innovation in varieties, and has brought about changes in rice breeding and production. Understanding the evolution of rice generations is helpful to grasp rice development direction.