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应用频次拟合法对植物病株(或病斑)进行田间分布型测定,调查麻烦,计算繁琐,并易出现各种分布型皆不符合的现象,不便推广应用。六十年代以来,应用研究昆虫种群空间分布型的种群扩散型指数等方法,近年来在研究植物病害病株空间分布型方面有所应用(敬甫松等1983,刘逸卿等1984)。我们在应用频次拟合法的同时,采用扩散系数(C)、扩散型指数(Iδ)及平均拥挤度(M)等方法进行小麦纹枯病病株空间分布型的测定,同时进行了抽样数量的测定。 田间调查方法 小麦品种分别为郑州761,百泉3039,宝丰7278,长势均匀一致,小区面积0.1亩。 于小麦抽穗期进行纹枯病发病情况调查。采用全查法,每小区中间查一行。以10株为一样本单位,每行共查500个样本,记载每样本病株数。三个品种,共查10个小区。 于小麦抽穗期、灌浆期分别进行五点抽样、棋盘式抽样和“Z”字形抽样。抽样田块小麦品种为百泉3039,重复三次,每次样本数分别为200株和300株,并用全查法(5000株)的结果作为对照。
Frequency fitting method of plant disease (or lesion) field distribution determination, investigation of trouble, calculation cumbersome, and prone to all kinds of distribution are not consistent with the phenomenon of inconvenient to promote the application. Since the 1960s, the application of population dispersal index method for studying insect population spatial distribution has been applied in the study of spatial distribution of plant disease diseased plants in recent years (Jingusuu et al 1983, Liu Yiqing et al 1984). Using the method of frequency fitting, we used the methods of diffusion coefficient (C), diffusion index (Iδ) and average crowding degree (M) to determine the spatial distribution of wheat sheath blight diseased plants. At the same time, Determination. Field survey methods Wheat varieties were Zhengzhou 761, Baiquan 3039, Baofeng 7278, growing evenly, the plot area of 0.1 acres. Investigation on the incidence of sheath blight in wheat heading stage. Using full check, check the middle row of each district. Taking 10 strains as a sample unit, a total of 500 samples were examined in each row, and the number of diseased plants per sample was recorded. Three varieties, a total of 10 plots. In the heading stage and filling stage of wheat, five samplings, checkerboard sampling and zigzag sampling were conducted respectively. The sampled plots of wheat varieties were Baiquan 3039, repeated three times with 200 and 300 samples per sample, respectively. The results of the whole method (5000 plants) were used as a control.