Abstract: The relationships between per panicle weight loss rate and per panicle’s number of rice false smut ball and diseased grains were calculated, respectively. The results indicated that there were significantly negative correlation between panicle weight and per panicle smut ball numbers and diseased grains. According to the per panicle smut ball numbers, rice false smut grading standard was determined: grade 0, 1, 2, 3, 4 and 5 corresponding to 0, 1, 2, 3, 4~5 and more than 6 （including 6）smut balls per panicle. On the other hands, according to the per panicle diseased grain numbers, rice false smut grading standard was determined: grade 0, 1, 2, 3, 4 and 5 corresponding to 0, 1, 2~3, 4~6, 7~13 and more than 14 （including 14） infected grains per panicle. The authors suggested that per panicle smut ball numbers should be adopted for grading standard of rice false smut in investigation in the field. Nevertheless, it was better by using per panicle diseased grain numbers as grading standard of rice false smut in the experiments and demonstration projects.

Key words: rice false smut, grading of disease severity, standard

摘要： 根据单穗稻曲球数和单穗病粒数的不同，分别计算与穗质量损失率的关系。结果表明，单穗稻曲球数和单穗病粒数与穗质量存在极显著的负相关关系。以单穗稻曲球数为分级标准，0~5级的各级稻曲球数分别为0、1、2、3、4~5、6以上；以单穗病粒数为分级标准，0~5级的各级单穗病粒数分别为0、1、2~3、4~6、7~13、14粒以上。根据研究结果，建议在稻曲病病情调查时使用以单穗稻曲球数为标准的病情分级方式，在试验示范项目中使用以单穗病粒数为标准的病情分级方式。

关键词: 稻曲病, 病情分级, 标准