Regulation of Regeneration Rate to Enhance Ratoon Rice Production

Ratoon rice (Oryza sativa L.) is a sustainable planting model, and its planting area has been increasing year by year. However, there is a lack of literature reviewing the measures and mechanisms to regulate the regeneration rate, as well as the challenges in the production of ratoon rice. This study explores the effects of different varieties, climatic conditions (light and temperature), and cultivation measures (fertilizer management, cropping system, harvest method, water management, and plant growth regulators) on the regeneration rate and grain yield of the ratoon season. It summarizes 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 main factors currently limiting the development of ratoon rice. A significant positive correlation between the regeneration rate and grain yield of the ratoon season was found, regulated by varieties, temperatures, light resources, and cultivation measures. Improving the regeneration rate can effectively increase the production of ratoon rice. Notably, rice varieties with high regeneration ability exhibit characteristics such as a suitable growth period, a developed root system, high single-stem weight, a relatively small ratio of grain number to green leaf area, and strong lodging resistance in the main season. Additionally, the germination of regenerated buds is regulated by the accumulation and transport of endogenous hormones (indole-3-acetic acid, gibberellins, and cytokinins), photoassimilates (non-structural carbohydrates), and reactive oxygen metabolism. To further demonstrate the grain yield potential of the ratoon season, improvements are needed in three key areas: the cultivation system of low-stubble ratoon rice, the development of specialized harvesters, and the breeding of rice varieties with high-temperature tolerance during the main crop and low-temperature tolerance during the ratoon crop.