The Evaluation of Resistance and Resistant Mechanisms of Peanut Varieties to Scab Disease

【Objective】Identification of the resistance of peanut varieties against scab disease could provide useful information for breeding resistant varieties of the peanut【.Method】The seedlings of 32 varieties were inoculated with the spore of scab pathogen.Scientists observed disease development in the field and detected enzyme activity and MDA concentration in the leaves.Scientists conducted micro-measure and pathogenisis review on cortical structure of 8 varieties.【Result】The results showed that 11 varieties,including Eyou 5 and Huaihua 8,were susceptible;10 varieties,including Puhua 16 and Jinhuasheng 1,were moderate susceptible;8 varieties,including Eyou 9 and Huaihua 8,were moderate resistant;3 varieties,including Xuhua 8,were resistant.The observation of different parts of leaves of varieties showed that the disease rates in the top leaf of the MR-R varieties were 0-23.8%.The rate of the V、VI disease index leaves was zero.While in the MS-S varieties,the disease rates were 84%-100%,and the rate of the V、VI disease index leaves were 10.7%-37.1%.The physiological tests showed that following disease development,the enzyme activity of POD and the concentration of MDA in the leaves were raised,while the activities of CAT and SOD were decreased.The micro-measure of different parts and different stages of leaves revealed that the different reactions to scab pathogen were determined by the structure of leaf epidermis.The leaves of resistant varieties had thick cutin and less stoma density.Therefore,in the resistant varieties,the latent period of disease was long,caused less lesions in the leaves and less disease carriers in the seed pods.【Conclusion】The main cultivated varieties in the fields,such as Quanhua 10,were susceptible.They had thin cutin and more stoma density in the leaves,which led to shorter latent period of disease,more lesions in the leaves and more spores released in the lesions.Those were the reasons explaining the epidemic of the disease in the fields.