Three-Line Hybrid Rice in China: Sustained Improvements in Yield, Quality, and Resistance Over Fifty Years

China pioneered the commercial application of hybrid rice ( Oryza sativa L.) throughout the world. Not only did Chinese scientists demonstrate that self-pollinating plants can achieve hybrid vigor, which was a groundbreaking theoretical breakthrough; they also established commercial rice breeding as one of China's most advanced agricultural models. In doing so, they made remarkable contributions to national food security. This paper looks back at 50 years of evolution of the three-line varieties of rice approved by the state and provinces through analyzing the following: statistics of the approval of varieties of individual restorer/sterile lines, dynamics of the area of adoption of specific rice varieties, and phenotypic changes in key agronomic traits, including yield and the grades of quality and resistance. The study comprehensively reviews China’s extraordinary journey in three-line hybrid rice breeding over the past half century, summarizes major achievements and lessons learned, and explores future directions for the three-line breeding of rice.