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本文引入聚集度指数(I;C;Iδ和M等)及平均拥挤度～平均密度系数的测定方法研究了纹枯病(Pellicularia sasakii)株在杂交稻田的空间分布型。研究表明,纹枯病株和丛的分布是:分布的基本成份是聚集的(α>0),即有明显的成团性。而集群内的分布是均匀的(β<1)。发病丛率(M)与病株率(P)间关系可由经验模型:(?)=0.28004M~(1.07148)(R=0.942,P<0.01;X~2=56.21,P>0.05)来描绘;当发病丛率大于50%,则更符合指数曲线关系:(?)=3.50743e~(0.02886M)(R=0.91,P<0.01)发病株率(P)与病情指数(Y)之间的关系,亦可用曲线方程:(?)=25.4004Ln[-Ln(1-P)]~(0.95904)(X~2=28.82,P>0.05)来定量表述。借助经验模型,可由发病丛率估算出发病株率,进而对病情指数作出可信的估计,从而实现更简易的抽样。据空间分布信息,以平行跳跃式抽取13样方(即65丛),用于纹枯病调查,其精确度达83%以上。
In this paper, the spatial distribution patterns of Pellicularia sasakii strain in hybrid rice paddy were studied by measuring aggregation degree index (I; C; Iδ and M) and average crowding degree ~ average density coefficient. Studies have shown that the distribution of sheath blight and plexus is: the distribution of the basic components are aggregated (α> 0), that is, there are obvious agglomeration. The distribution within the cluster is uniform (β <1). The relationship between incidence rate (M) and disease rate (P) can be described by empirical model: (?) = 0.28004M ~ (1.07148) (R = 0.942, P <0.01; X ~ 2 = 56.21, P> 0.05) ; When the plexus incidence rate is more than 50%, the relationship between the exponential curve and the disease index (Y) is more in line with the exponential curve: (?) = 3.50743e ~ (0.02886M) (R = 0.91, P <0.01) The curve equation can also be used to quantify the expression: (?) = 25.4004Ln [-Ln (1-P)] ~ (0.95904) (X ~ 2 = 28.82, P> 0.05). With empirical models, the rate of diseased plants can be estimated from the incidence plexus, which in turn gives a credible estimate of the disease index, resulting in a simpler sampling. According to the spatial distribution information, 13 samples (ie 65 plexuses) were extracted by parallel jumping for the investigation of sheath blight, with an accuracy of over 83%.