海南岛芋疫霉菌生物学特性、致病力、对甲霜灵的敏感性研究

从生物学、致病力、对甲霜灵的敏感性等侧面对海南岛１９个县市的芋疫霉菌（Ｐｈｙ－ｔｏｐｈｔｈｏｒａ ｃｏｌｏｃａｓｉａｅ　Ｒａｃｉｂ）进行研究，结果表明：芋疫霉种下存在丰富的多样性。孢襄形态差异显著，长宽比１．３６～２．６，大小从（１７．５－）３９．５（－８２．５）×（１０．０－）２３．３（－３５．０）μｍ到（４０．０－）５６．０（－９２．５）×（２２．５－）３０．５（－４０．０）μｍ。大部分菌株的最适生长温度２５～３０℃，最适温度下各菌株的生长速率差异显著，从０．５６２ｃｍ／ｄ到０．８２９ｃｍ／ｄ。两种交配型（Ａ１：Ａ２）比例接近于１。各菌株对芋头材料的致病力有明显不同。对甲霜灵的敏感性也显著不同，ＥＣ５０值０．０７７ μｇ／ｍＬ～０．４４８μｇ／ｍＬ。生物学、致病力、对甲霜灵的敏感性等性状的分布似乎与地理位置有关。多元聚类将１９个菌株分成６类。

Study on the Biology, Virulence of Phytophthora colocasiae Racib and Its Sensitivity to Metalaxyl

Nineteen strains of Phytophthora colocasiae obtained from different locations in Hainan Island were tested for morphological characteristics growth rate virulence to taro and sensitivity to Metalaxyl. The Results showed that there was considerable diversity within this species. The sporangial sizes of different strains were significantly different with L/B ratio ranging from 1.36 to 2.6. The optimum temperature for growth of most of the strains (17 strains) was 25 ℃. However the growth rate under the optimum temperature varied considerably among these strains ranging from 0.562 cm/d to 0.828 cm/d. Virulence test with inoculating the strains on taro materials indicated that the virulence of these strains was significantly different from each other. Sensitivity to Metalaxyl was also evidently different with the values of EC50 ranging from 0.077 μg/mL to 0.448 μg/mL. The morphological characteristic distribution had something to do with the geographical position. The 19 strains were divided into 6 groups according to cluster analysis.