苜蓿霜霉病病原及其生物学特性研究

目的]对天水地区苜蓿霜霉病病原及生物学特性进行较为系统的研究。方法]在苜蓿生长季节，观察和描述症状。采用悬滴法，研究温度、pH值和营养液对孢子囊萌发的影响，采用硫酸法控制小容器相对湿度测定湿度对孢子囊萌发的影响。结果]经鉴定，苜蓿霜霉病病原为Peronospora aestivalis Syd，孢子囊萌发的适宜温度为15—21℃，最适温度为18℃；孢子囊在相对湿度100％时的萌发率为5．56％，相对湿度低于95％时不能萌发；孢子囊萌发的适宜pH值为6．15～7．69，最适pH值为6．91；1：5的苜蓿叶片汁液对孢子囊的萌发有较强的刺激作用。结论]该研究为苜蓿霜霉病的防治提供理论依据。

Study on Pathogen and Its Biological Characteristics of Alfalfa Downy Mildew

Objective]The research aimed to study the pathogen of alfalfa downy mildew and its biological characteristics.Method]The disease was observed in the field.Germination rate of sporangium in different temperature,pH and nutrition was examined with suspending drop method.Slide germination method was used to observe its germination in different humidity maintained by different concentration of H2SO4.Result]The pathogen was Peronospora aestivalis Syd.The optimum temperature range for sporangium sprot was from...