稻曲病（Ustilaginoidea virens）病穗和病粒的空间分布型

用频次分布法测定了水稻稻曲病病穗和病粒在稻田中的分布，结果表明：在２０块稻中，有１９块田曲病病穗分布符合聚集分布，仅１块田符合随机分布，稻曲病病粒的分布在１９块田中均符合聚集分布。又用８种聚集度指数测定了稻曲病病穗和病凿的分布型。结果表明，稻曲病的病穗和病粒的分布均是聚集的，其分布的基本成分为疏松个体群，个体群内分布是随机的。病穗和病粒的个体群面积分别为４－８穴和２－４穴。

Spatial distribution patterns of diseased panicle and diseased grain of rice green smut (Ustilaginoidea virens)

The test of frequency distribution and 8 indices of aggregation were used to study the spatial distribution patterns of diseased panicle and diseased grain of rice green smut caused by Ustilaginoidea virens in late paddy. The results indicated that 19 out of 20 sets of diseased panicle samples and all 19 sets of diseased grain samples fitted an aggregated pattern, and that only one, in which the mean of diseased panicle was the lowest(0.12 panicle per hill), fitted a random pattern. All indices indicated that the distribution of the diseased panicle and diseased grain of rice green smut were of an aggregated pattern. The basic component of distribution was loose colonies, the distribution pattern of basic components was aggregated and intra colony distribution was random. The sizes of colony of diseased panicle and diseased grain of rice green smut were 4 8 hills and 2 4 hills respectively.