玉米茎腐病病原菌致病性及侵染规律的研究

Study on Regularity of infection and Pathogenicities of Pathogenic Fungi of Corn Stalk Rot

利用禾谷镰刀菌（Ｆｕｓａｒｉｕｍｇｒａｍｉｎｅａｒｕｍ）、永生腐霉菌（Ｐｙｔｈｉｕｍｇｒａｍｉｎｉｃｏｌａ）和链状腐霉菌（Ｐｙｔｈｉｕｍｃａｔｅｍｕｌａｔｕｍ）３种玉米茎腐病的病原菌通过两年的试验进行了对玉米抗病品种和感病品种的致病性和侵染规律的研究。结果表明：在大田自然条件下，３种病原菌对玉米植株均有致病性．其中以禾谷镰刀菌的致病性最强，其次是禾生腐霉菌和链状腐霉菌。禾谷镰刀菌和腐霉菌在植株散粉盛期以前的侵染规律符合苗期致病性试验的结果。二者侵染致病作用的部位不同。禾谷镰刀菌主要是胚根，腐霉菌主要是次生根和须根。在感病品种中，病原菌侵染的高峰期从散粉盛期开始。而在抗病品种上则从灌浆期开始。在灌浆期以前，病原菌只能侵染植株的根系。以后则侵入植株的茎部组织到乳熟期侵入到第三茎节。本试验的结论客观地反映了玉米茎腐病病原菌在大田自然条件下的致病性和侵染规律。

The pathogenicities of pathogenic fungi (Fusarium graminearum,Pythium graminicola and Pythium catenulatum)were tested in resistant and susceptible varieties of corn in 1993 and 1994.The results showed that all these three species of fungi could cause the corn stalk rot.The pathogenicity of Fusarium graminearum is stronger than that of other two species.Before middle anthesis of corn the regularity of infection of Fusarium graminearvm and Pythium spp is in correspondence with the testing result at seedling of corn.The infection positions of Fusarium graininearum and Pythium.spp were different.Fusarium graminearum infected radicle.However Pythium sPP infected secondary root and fibrous root.The infection peak of these three pathogenic fungi started in middle anthesis in susceptible variety and in milk stage in resistant variety. The pathogenic fungi only infected the roots of corn before milk stage. After the milk stage they could infect the inside of the stalk of corn and even to the third node of the stalk.