水稻纹枯病不同分级标准病情指数间的关系

研究了水稻纹枯病不同分级标准的病情指数间的关系以及病株率与病情指数间的相互关系。结果表明;按9级标准计算的病指与按4级或5级标准计算的病指间的关系均可用线性函数描述。在病指<0.07时,按9级标准计算的病指与按国际9级标准计算的病指间的关系也呈线性关系;当病指>0.07时,呈幂函数关系。病株率与病指间的关系呈幂函数关系。分别建立了这些关系的数学模型,经检验结果基本合理可靠。本文还讨论了这些关系在病害监测上的应用。

Relationships among Disease Indices of Different Gradation Standards of Rice Sheath Blight

The relationship among disease indices (DI's) of different gradation standards of rice sheathblight, and the relationship between disease incidence and severity (I-S relationship) were studiedthrough field trials individually. The results showed that the relationship between DI of the 9-grade-standare and the 4-grade-standard, the relationship between DI of the 9-grade-standard andthe 5-grade-standard might be determined with linear functions. The relationship between DI's of9-grade-standard and international 9-grade-standard (DI9--DI9' relationship) could be describedwith linear function as well when DI of international 9-grade-standard was below 0. 07; DI9-DI9' relationship might be desribed with exponential function when DI9' was above 0. 07.Equations for these relationships of rice sheath blight were build up individually. Simulated curveswere compared with actual value that had not been used in developing model. The result indicatedthat the models were reasonable. Rice growth stage did not affect the relationship of DI's ofdifferent gradation standard evidently, but affected I-S relationship of rice sheath blight. It wasdicussed how to use the relationships in disease monitoring.