桂花叶斑病病原鉴定及其生物学特性研究

从桂花(Osmamthus fragrans)叶斑病病斑上分离得到叶点霉病原菌,对病原菌形态特征进行观察,经鉴定该病原菌为变叶木叶点霉（Phyllosticta ghaesembillae Koorders）。同时对该病原菌的致病性及其生物学特性进行了研究。结果表明: pH3～11条件下均适宜该病原菌菌丝生长,最适合孢子萌发的为pH 9。菌丝生长和分生孢子器形成的最适温度为25?℃,分生孢子萌发的最适温度为20?℃。光照对该病原菌的菌丝生长无显著影响,黑暗对孢子的萌发有一定促进作用。该病原菌可利用多种单糖、双糖、多糖等碳源,但这些碳源对病原菌的生长无显著影响,只对孢子萌发率有一定的影响。同时该病原菌也能利用有机氮、无机氮等氮源,最适氮源为硝酸钾,硫酸铵和氯化铵会抑制病原菌菌丝生长。菌丝致死温度为60?℃。

Pathogeny Identification and Biological Characteristics of the Leaf Spot Lesions of Osmamthus fragrans

In this study Phyllosticta spot pathogen was isolated from the leaf spot lesions of Osmamthus fragrans and  identified as Phyllosticta ghaesembillae Koorders. Meantime the Pathogenicity and the biological characteristics werestudied． The result showed: this pathogen can grow at pH value 3-11　and themostoptimal pH value was 9. The most optimal temperature for the growth of hyphae and the generation of Pycnidium was 25℃, but the most optimal temperature for germination of Conidia was 20?℃. No significant influence of illumination on thegrowth of hyphae was observed. Darkness helped the germination of spore. Many kinds of monosaccharide, disaccharides and polysaccharide can be used by the pathogen which did not influence  the growth of hyphae but  on the growth percentageof hyphae. The pathogen can utilize the organic nitrogen an inorganic nitrogen in which KNO₃　was the suitable nitrogen source. (NH₄)2SO4 and NH4Cl repressed the growth of pathogen. The lethal temperature of hyphae was 60℃ per 10min.