Innovations in Hybrid Rice Seed Production: Integrating Agronomy, Mechanization, and Biotechnology

Hybrid rice utilizes heterosis to significantly safeguard global food security. However, the dominant "three-line" and "two-line" seed production systems rely heavily on manual labor and are highly vulnerable to climate fluctuations. These limitations have become a core bottleneck for the industry's sustainability. To address this, this review systematically summarizes recent advances and proposes a novel "dual-track" analytical framework. The Proximal Track focuses on integrating agronomy with machinery. It analyzes mechanized innovations in split- and mixed-planting models, evaluating mixed-sowing strategies based on targeted phenotypic sorting (seed coat color and grain thickness), selective herbicides, and gene editing (thermosensitive female sterility). Meanwhile, the Distal Track explores molecular-driven breakthroughs. It clarifies the core advantages of third-generation seed production technology (SPT) for enabling unrestricted crossing and the large-scale propagation of male sterile lines, before analyzing the latest progress in "one-line" synthetic apomixis for the permanent fixation of heterosis. Finally, the manuscript proposes creating tailored parental chassis varieties for mechanization and introducing AI-driven meteorological-crop models to predict complex genotype-by-environment risks. Ultimately, this framework guides the paradigm shift from "Agronomic-mechanistic integration" to "Reproductive pathway rewiring," laying a solid foundation for the strategic leap from the "three-line" and "two-line" systems to the "one-line" method.