National Key R&D Program of China (2022YFD2301100)；supported by Yunnan Fundamental Research Projects (grant NO.202101AT070273）
Ratooning ability is a key trait for breeding a new sugarcane cultivar. Sugarcane has a long growth cycle, and there are many factors that affect the rooting ability. Therefore, the evaluation of rooting ability has always been a difficulty. This study used 212 sugarcane germplasm resources from different countries and regions at home and abroad as research materials, and conducted a rapid evaluation of sugarcane ratooning ability using the method of two harvests each year in Longan, Guangxi and Kaiyuan,Yunnan, respectively. The comprehensive evaluation of sugarcane ratooning ability was conducted using the combination of two important traits, namely plant growth and aboveground stalk biomass and the main components. The results showed that the distribution frequency of all indexes showed a trend of being high in the middle and low on both sides, but all showed a non-normal distribution. The ratooning ability of sugarcane is greatly affected by environmental conditions, and there are extremely significant differences in the four ratooning indexes at two points. There is a highly significant positive correlation between the two indexes. Only one principal component was extracted from both experimental sites, with a principal component contribution rate of 80.25% in Kaiyuan, Yunnan site, and 62.68% in Longan, Guangxi site. Cluster analysis divided the 212 germplasm materials into 10 subgroups of 5 groups. For the entries in the first group, 4 individual indexes of ratooning ability were all at a high level, making them the first choice for strong ratooning germplasm resources, with only 9 materials. For those in the second and third groups, various indexes showed relatively high levels or individual indexes were very prominent. This group can be used as the second echelon of strong ratooning germplasm resources, and it contained a total of 38 germplasm resources. For the entries in the fourth and fifth groups, various indexes showed an average or poor ratooning ability, and they were not recommended to be used as strong ratooning germplasm resources, and it contained a total of 165 germplasm resources, accounting for 77.83%. The scarcity of high-quality and strong ratooning germplasm resources indicates that strengthening and accelerating the evaluation of sugarcane germplasm resources are important for breeding the new varieties with strong ratooning ability.