西瓜炭疽病人工接种鉴定的新方法──离体叶接种和AD评价法

对具有不同抗性水平的３个西瓜品种进行了离体叶人工接种炭疽病抗性鉴定方法的研究。结果表明，离体叶与幼苗人工接种同样能够真实地反映西瓜品种固有的抗病性，且能节省菌液、劳力、试材和费用，并对环境条件更易控制，简便易行，可以广泛采用。该法用注射器悬滴接种，菌液浓度为１×１０￣６孢子／ｍＬ。接种叶片的叶龄为１５～２０ｄ，接种后３ｄ开始发病，第６ｄ调查统计病情指数。品种抗病性可以用平均病斑直径（ＡＤ），（发病病斑直径）／接种总滴数］和病情指数（ＤＩ）两种标准进行评价，其中用ＡＤ进行品种抗病性评价减少病级划分中的人为误差，更为客观简便，可以取代ＤＩ在离体叶人工接种西瓜炭疽病抗性鉴定中广泛采用。

A New Method for Identifying Colletotrichum lagenarium of Watermelon-Inoculating with Detached Leavesand Judging Resistance with AD Standard

Three watermelon cultivars (Xingcheng Red,Charleston Gray and Congo)with different levels of resistance were identified using artificial inoculation method with detached leaves.There sults showed that the detached leaves and Young seedling artificial inoculation were able to reflect the distinctive disease resistance of watermelon cultivars accurately so that spore suspension,labor and materials and cost were reeuced, and the environmental conditions were easy to control;and the method was easy to operate and wide to use:The microinjector was used in suspension inoculation.And the optimum spore concentration for inoculation was 1 X 106 spores/mL.The inoculated detaehed leaves presented symptoms at 3 days after inoculation,and their disease severity indexes were surveyed at 6 days after inoculation.The resistance to anthracnose of watermelon cultivars was judged by two standards,such as average diameter of lesion(AD,AD=summation of the diameters of lesions/total drops of inoculation) and disease index (Dl),of which using AD to carry out evaruation of disease resistance might deminish man-mde error in growing disease seales,which is more obijective and simpler.Also, AD can be extersively used in identification of resistance to anthracnose of watermelons instead of disease index of disease index (Dl).