Yuen Jonathan E, Forbes Gregory A
Department of Forest Mycology, Swedish University of Agricultural Sciences, SE 750 05 Uppsala, Sweden.
Phytopathology. 2009 Jun;99(6):782-6. doi: 10.1094/PHYTO-99-6-0782.
Resistance and susceptibility are closely related terms but differ in their underlying assumptions and measurement. Standardized methods for determining the level of resistance and susceptibility in potato to Phytophthora infestans, the causal agent of late blight, have traditionally been semiquantitative and are not based on a true interval scale, thus making their use in most mathematical and statistical operations inappropriate. Recently, researchers have attempted to develop interval scales using regression analysis of the direct or transformed area under the disease progress curve (AUDPC). In this article, a similar approach is described based on the relative AUDPC (RAUDPC) of one or two reference cultivars and tested using a data set of field trials involving cultivars with varying levels of susceptibility evaluated in different environments in several countries. The coefficient of variation (CV) among trials of the AUDPC was reduced when the RAUDPC was used and even more so when the RAUDPC was made relative to the RAUDPC of cv. Bintje (RaRAUDPC), which was present in all trials. The RaRAUDPC was used in regression models to estimate scale values for eight potato cultivars in 13 to 15 locations (depending on cultivar). The CVs of scale values measuring variation among sites were similar to those of the RaRAUDPC. Using two cultivars gave a slight improvement in CV, which was statistically significant. The scale developed here has ascending numbers for increasing susceptibility, is simple, and can be constructed as a ratio measure, which permitted the calculation of mean, variance, and CV.
抗性和易感性是密切相关的术语，但在其潜在假设和测量方法上有所不同。传统上，用于确定马铃薯对晚疫病病原菌致病疫霉的抗性和易感性水平的标准化方法一直是半定量的，且并非基于真正的区间尺度，因此使其在大多数数学和统计运算中的应用并不合适。最近，研究人员试图通过对病害进展曲线下的直接面积或转换面积（AUDPC）进行回归分析来开发区间尺度。在本文中，描述了一种基于一个或两个参考品种的相对AUDPC（RAUDPC）的类似方法，并使用了一个田间试验数据集进行测试，该数据集涉及在几个国家不同环境中评估的具有不同易感性水平的品种。当使用RAUDPC时，AUDPC试验间的变异系数（CV）降低，而当RAUDPC相对于所有试验中都存在的宾杰品种（cv. Bintje）的RAUDPC（RaRAUDPC）时，CV降低得更多。RaRAUDPC被用于回归模型，以估计13至15个地点（取决于品种）的8个马铃薯品种的尺度值。测量地点间变异的尺度值的CV与RaRAUDPC的CV相似。使用两个品种时，CV略有改善，这在统计上是显著的。这里开发的尺度随着易感性增加而数字上升，简单且可构建为比率度量，这允许计算均值、方差和CV。
