Types and methods of Indica super rice varieties in the middle and lower reaches of Yangtze River

【Objective】To provide scientific support for giving full play to super-high-yield potential of super-rice varieties through the precise matching of super-high-yield and stable-yield cultivation techniques, studied the panicle-grain typing indicators and methods of super rice varieties in the middle and lower reaches of Yangtze River.【Method】Taking 68 Indica type super rice varieties as the classification objects, which passed the national approval(in the middle and lower reaches of Yangtze River) or by Hunan, Hubei, Jiangxi, verified the scientificity of the classification results of the classification coefficient method, through the comparison with the literature classification method, the expert experience method and the comparison between data from different sources.【Result】The classification coefficient method divided 8 cultivars such as Ganxin 203 and Shengtaiyou 722 into multi-panicle or partial-panicle cultivars, and 8 cultivars such as Luliangyou 996 and Wuyou 368 were divided into panicle-grain balance type, 52 cultivars such as Wufengyou 286 and Wufengyou T025 were classified as large panicle or partial grain cultivars. Among the 25 varieties that have been approved for multiple times, the classification coefficient method showed that 88.0%(22) of the varieties had the same classification results in different years and regions. And that meaned the classification coefficient method could better eliminate the interference of environmental variation on variety typing, and within a certain environmental variation limit, the genetic characteristics of the variety itself could be displayed more stably. Compared with the previous literature, the classification coefficient method made up for its shortcomings that it could only distinguish panicle-large type varieties and could not distinguish paniclerich type and panicles-grains-balanced type varieties, and the classification results were more repeatable. Compared with the expert experience method, the classification coefficient method has stronger ability to classify and aggregate varieties with similar panicle and grain number characteristics, and the variability or randomness of the typing results was smaller, more reasonable and accurate, and easier to master and widely popularized.【Conclusion】The classification coefficient method is more advantageous than the existing methods for panicle-grain classification of indica super rice varieties in the middle and lower reaches of the Yangtze River, and is of great significance to promote the full potential of super rice varieties to achieve high yield.