小麦赤霉病秆腐症状形成的主要途径

The Main Way of Stem Rot Symptom Development of Wheat Scab

禾谷镰孢菌(Fusarium graminearum)分生孢子液滴注到小麦旗叶叶鞘内可引发小麦穗期秆腐。孢子液在破口期接种到穗下叶鞘内秆腐发病率达69.35%,接种到麦穗和叶鞘之间,秆腐发病率为25.8%,发病茎秆有52.7%出现节间发病;推迟到麦穗快抽出叶鞘时在鞘内接种,只有3.66%的茎秆发生秆腐。根据接种的发病结果与叶鞘枯斑、节间发病时间分析,小麦破口抽穗期病菌随雨水、露水从叶鞘裂隙流入旗叶叶鞘内可能是造成秆腐的主要原因。

The present study aimed to identify the cause of development of stem rot symptoms of wheat scab.A conidial suspension of Fusarium graminearum was injected into the sheath of the wheat flag leaf;consequently,wheat stem rot symptoms were developed at heading stage.When a spore suspension of F.graminearum was inoculated to plants at initial heading stage,the incidence rate of stem rot differed with inoculation site,which reached 69.35%in the treatment with the pathogen inoculated to the leaf sheath under a spike,but 25.8%in the treatment with the pathogen inoculated between the spike and leaf sheath.Moreover,internode rot was manifested in 52.7%of the stems with rot symptoms.However,when the spore suspension was inoculated to the leaf sheath under a spike at full heading stage,only 3.66%of the stems developed rot symptoms.These results indicate that the incidence rate of stem rot varies with inoculation time and site,suggesting that development of stem rot symptoms of wheat scab may be mainly caused by the pathogen flowing with rain and dew into the flag leaf sheath from its crack at initial heading stage.