Regulation of Regeneration Rate to Enhance Ratoon Rice Production

Ratoon rice (Oryza sativa L. ) is a sustainable planting model, the planting area has been increasing year by year. And the grain yield of the ratoon season is closely related to the regeneration rate. However, there is a lack of literature review on the measures and mechanism to regulate the regeneration rate, and the challenges in the production of ratoon rice. This study was to explore the effects of different varieties, climatic conditions (light and temperature) and cultivation measures (fertilizer management, cropping system, harvest method, water management, and plant growth regulator) on the regeneration rate and grain yield of the ratoon season from the published papers, summary and analyzes the possible mechanisms that affect the germination of regenerated buds from the perspectives of material accumulation and transportation, hormone metabolism, and molecular mechanisms, and identifies the main factors that currently limit the development of ratoon rice. A significant positive correlation ( r = 0.724, P < 0.001) between regeneration rate and grain yield of the ratoon season, regulated by varieties, temperature and light resources, and cultivation measures, and improving regeneration rate can effectively increase the production of ratoon rice. Notably, rice varieties with high regeneration ability had the characteristics of suitable growth period, developed root system, high single stem weight, relatively small the ratio of grain number to green leaf area and strong lodging resistance in the main season. Additionally, the germination of regenerated buds was regulated by the accumulation and transport of endogenous hormones (indole-3-acetic acid, gibberellins, and cytokinins), photoassimilate (non-structural carbohydrates), and reactive oxygen metabolism. To further unleash the grain yield potential of ratoon season, the planting mode of low-stubble ratoon rice, special harvester, and specialized varieties that have high temperature tolerance during the main crop and low temperature tolerance during the ratoon crop, needs to be further improve.