甘蓝枯萎病苗期抗病性鉴定方法

以4种田间不同抗枯萎病类型甘蓝品种幼苗为试材,以分离甘蓝枯萎病病原菌悬浮液为接种菌液,筛选苗期抗病性鉴定最适接种浓度、最佳方法和最适苗龄;确定植株感病级别划分指标,判断抗病类型。结果表明,甘蓝枯萎病苗期抗病性鉴定最适接种浓度5×106孢子·mL~(-1);比较灌菌液法、菌土法和浸根法3种接种方法,菌土法接种可更准确反映不同抗病性品种枯萎病发病程度和抗病类型;在子叶期、一叶一心期、二叶一心期、三叶一心期不同幼苗期接种,后两个时期特别是二叶一心期为最佳接种期;依据幼苗植株叶脉黄化程度,植株叶片褪绿、萎蔫甚至枯死等发病主要症状,将甘蓝感病幼苗划分为6个级别。由此确定甘蓝枯萎病苗期抗病性鉴定方法:种子消毒育苗,待幼苗长至二叶一心期时,采用幼苗轻微伤根、菌土法,接种5×10~6孢子·mL~(-1)枯萎病菌液,16 d后调查统计幼苗植株发病程度和感病级别数量。

Study on identification method of disease resistance of cabbage wilt at seedling stage

Four cabbage seedlings with different resistances to Fusarium wilt in the field were selected as test materials, and the suspension of pathogenic bacteria isolated from cabbage wilt was used as inoculation solution to screen the optimum inoculation concentration, method and seedling age for identification of disease resistance at seedling stage, and to determine the classification criteria of susceptible plants and determine the type of disease resistance. The results showed that the optimum inoculation concentration was 5×10~6 spores· mL~(-1) with disease resistance of cabbage wilt at seedling stage; comparison of three kinds of inoculation methods, bacterial soil method and root soaking method,the inoculation method could better reflect the degree of disease and the type of disease resistance of different disease-resistant varieties; inoculation in the cotyledon stage, one leaf one heart period, two leaf one heart stage, three leaf one heart stage, and the other two stages, especially the two leaf one heart stage was the best inoculation period; according to the degree of leaf vein yellowing of the seedling plants, the plant leaves retreat the main symptoms of green, wilt and even death, the cabbage susceptible plants were divided into six levels. It concluded that the identification method of disease resistance in cabbage seedling stage was seed disinfection and seedling. When the seedling grows to the second leaf and one heart stage, the concentration of 5×10~6 spores· mL~(-1) Fusarium oxysporum was used, and the seedlings are slightly damaged and the soil was inoculated 16 days after inoculation.The disease incidence and the number of susceptible grades of the seedling plants were counted.