荔枝叶面、花穗和果实上真菌消长动态

用组织分离方法对荔枝不同发育时期和不同部位的致病和非致病真菌进行系统分析,结果分离到14个属的真菌,其中致病菌11种,非致病菌3种.炭疽属Colletotrichum sp.和拟茎点霉属Phomopsis sp.真菌在叶片、花穗和果实上属于常驻菌群;非致病菌壳囊孢属Cytospora sp.真菌全年出现在成熟叶片上,分离频率为43.7%;而芽枝孢属Cladosporium sp.和链格孢属Alternaria sp.真菌在荔枝开花和挂果期广泛分布.茂名地区2009年降雨量为1 396.9mm,当日均降雨量在0.2～12.4 mm区间时,花穗和果柄上链格孢属真菌与日均降雨量呈正相关,一元线性回归方程为y=11.99+2.5 x(r2=0.99,P<0.01),而炭疽菌属、拟茎点霉属、芽枝孢属、白地霉属真菌与日均降雨量相关性不显著.果实上致病菌变化趋势为第2次生理落果期和果实成熟期含有致病真菌最多,采前落果期致病菌分离频率最低.在果实发育过程中,降雨量与其他因素共同作用影响致病菌分离频率.

Dynamic Changes of Fungi on the Leaves, Flower Clusters and Fruits in Litchi

Dynamic changes of fungi population were analyzed by tissue isolation on leaves,flower clusters and fruits in litchi.Fourteen genera of fungi were isolated,including 11 pathogenic fungi and 3 nonpathogenic fungi.Colletotrichum sp.and Phomopsis sp.belonged to resident population on litchi old leaves,flower clusters and fruits.In old leaves,isolation Cytospora sp.was resident all the year,and its isolation frequency was 43.7%.Alternaria sp.and Cladosporium sp.widely distributed at the stage of blossom and fruit bearing.The precipitation of Maoming in 2009 was 1 396.9 mm.There was a positive correlation between isolation frequency of Alternaria sp.and the daily mean rainfall in flower clusters and fruit stalks with 0.2-12.4 mm precipitation range,their one-dimensional linear regression equation was y=11.99+2.5 x(r2 =0.99,P<0.01),while there was no correlation between daily mean rainfall and isolation frequency of Colletotrichum sp.,Phomopsis sp.,Cladosporium sp.and Geotrichum sp..There were maximum pathogenic fungi at the second physiological drop and during fruit maturation,while the isolation frequency was the lowest at the last fruit-drop before harvest.The rainfall and other factors together affected distribution of pathogenic fungi.