Research progress on QTLs loci affecting rice retooning ability and screening system for ratoon rice

Mining rice yield potential is one of the most important directions of rice research. Ratoon rice is a kind of rice that utilizes the axillary buds that survive on the rice pile after the first season of harvesting, the buds germinate into tillers under suitable light, temperature, nutrients and other conditions, and then proceed to heading and maturity. Growing ratoon rice saves a lot of manpower and material resources while ensuring that the rice yield is basically the same as that of double-cropping rice, and it is of great significance for stabilizing national food security. In this paper, the reported QTLs related to rice retooning ability were reviewed, and we found that the contribution rates of the reported QTLs related to rice retooning ability were low, and the related research was not in depth and not closely related to production. The present situation of evaluation criteria for rice retooning ability was summarized. We found that the SPAD attenuation index of the first season rice in the early stage, the sprouting rate of ratoon rice in the middle stage, and the daily yield and heat utilization rate in the late harvest stage were important indicators for evaluating the retooning abilities of rice varieties, which could be used to screen rice varieties with strong retooning abilities. The effects of stump height on yield and quality of ratoon rice were summarized. Finally, we proposed to focus on important rice traits such as high quality, high yield, disease resistance, and other traits related to strong retooning ability, to mine new genes and their excellent natural variation by multi-omics analysis, to develop functional molecular markers, and to combine genome-wide association study with molecular module breeding technology to carry out research on accurate identification of rice germplasm resources with strong retooning abilities, new gene exploration, germplasm innovation and new variety breeding.