棉花黄萎病株空间格局及抽样技术研究

ON THE SPATIAL DISTRIBUTION PATTERNS AND ITS SA MPLIN TECHNIOUE FOR THE COTTON PLANTS INFECTED BY VERTICILLIUM

本文通过聚集度指标(包括:C、C_A、I、I_8、M/X和L/1+X)测定,以及Iwao’sM—X线性回归、Taylor’s幂的法则和格局纹理分析,结果表明棉花黄萎病株空间格局随着病株密度的提高逐步从聚集型向均匀型演变发展。其空间格局的基本成份是疏松的病株个体群,个体群所占面积约为5株棉花,平均约含2.4个病株个体,且个体群内的病株个体呈随机格局。经方差和u检验,结果表明单对角线五点式、双对角线五点式、棋盘式和平行跳跃式等4种取样方法均适用于棉花黄萎病的田间调查,且尤以双对角线五点式为佳。用双对角线五点式取样法调查的最适抽样数:一般病情普查可少至5个样方(每样方系5株棉花),科研调查为30个样方。

The spatial distribution patterns of the cotton infected by verticilliumwere measured by the six indices of aggregation intensity(inducing:C,C_A,I,I_8,(?) and L/1+(?))and the Iwao's M—(?) regresion and the Taylor'spower rules and the distributional vein.The results show the followingaspects:(1)The spatial distribution patterns of the cotton verticillium grad-ually develop from the aggregation distribution to the uniform distributionwith increase in the density of cotton verticillium wilt plants.The basiccomponent of the spatial distribution patterns is loos colony and the distri-bution of colony is uniform.(2) The intra—colony distribution is random.(3) The mean size of colony is about 5 cotton plants and equal to about 2.4individuals. The results of variance analysis and u test show that the all methodsof sampling(Single diagonal of five points,Double diagonal of five points,Scattering ang Paralled) are suitable for the investigation of the cottonverticillium wilt in cotton fields,and the double diagonal of five points isa best way of them.The sample numbers by the double diagonal of fivepoints might be less than 5 squares in the common investigation and 30squares in the scientific investigation.