芒果叶片对炭疽病的阶段抗性

Age-related resistance of mango leaves to anthracnose

为了研究芒果叶片对炭疽病的阶段抗性,在室内人工接种和田间自然发病条件下,对3个芒果品种的不同成熟度叶片的抗病性进行了鉴定,并测定了病原菌分生孢子在不同成熟度叶片表面的萌发率和附着胞形成率。结果表明,在室内人工接种条件下,随着芒果叶片逐渐成熟,对炭疽病的抗性逐渐增强,处于幼嫩期的古铜色叶片最为感病,病情指数在97.0以上,淡绿色叶片表现抗病,病情指数在2.0～2.5之间,成熟的老叶表现高抗或近免疫,病情指数为0。田间自然发病调查结果与室内试验结果基本一致,说明幼嫩的古铜色阶段是芒果叶片对炭疽病的易感期。随着芒果叶片成熟度的提高,病原菌分生孢子萌发率和附着胞形成率有下降的趋势,在古铜色叶片、淡绿色叶片和老叶表面分生孢子萌发率分别为98.1%～99.2%、95.0%～97.0%和86.0%～92.0%,附着胞形成率分别为74.4%～81.0%、70.0%～77.8%和63.4%～69.9%。

Age-related resistance in the leaves of 3 varieties of mango to anthracnose causalagent,Colletotrichum gloeosporioides Penz.,was determined.The result showed that disease onbronze leaves was significantly serious than that on light-green leaves and old leaves,whichwere high resistant or nearly immune to the pathogen.The number of disease lesion on bronzeleaves was much more than that on light-green leaves and old leaves.Spots on bronze leavesenlarged quickly,but these on light-green leaves and old leaves enlarged no longer.In thefield,the most infections occurred on bronze leaves.Infection hardly happened on light-greenor old leaves.The result of spore germination assay showed that spores germinated well on man-go leaves with different maturity,but the rate of spore germination on bronze leaves was higherthan that on light-green leaves and old leaves.While appressoria rates on bronze leaves,light-green leaves and old leaves had no significant difference.It is suggested that the difference inspore germination rate on leaves with different maturities is not the main cause of the age-relat-ed disease resistance of mango leaves.