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为了更有效地防治烟草野火病,对采自宜宾市烤烟种植区的具有典型野火病症状的烟叶样品进行了组织分离、培养和形态特征观察。采用针刺结合无针头注射接种法测定分离菌株的致病性,同时采用病菌生长速率法测定了不同致病力的菌株pv-xs-y-2(强)、pv-xt-y-2(中)和pv-gy-y-1(弱)的生物学特性及4种杀菌剂对强致病力菌株pv-xs-y-2的室内抑制效果。结果表明:14个菌株的形态特征均与烟草野火病病菌的形态特征一致,但各菌株间的致病力有明显的差异,平均病情指数为23.33~72.22。聚类分析结果显示,14个菌株在鉴别寄主(K326)上的致病力划分为强(病指为60~72.22)、中(病指为34.44~53.33)和弱(病指为23.33)3种类型,其中以中等致病力类型的菌株为主,占测试菌株的71.43%。在人工培养条件下,病菌的最适生长温度为28℃,pv-xs-y-2、pv-xt-y-2和pv-gy-y-1菌株的OD600值分别为1.285、1.105和0.977;最适生长湿度为100%,pv-xs-y-2、pv-xt-y-2和pv-gy-y-1的OD600值分别为0.694、0.555和0.505;最适p H值为7,说明野火病菌适宜在中性环境中生长。不同药剂对野火病室内毒力的测定结果依次为3%噻霉酮>4%春雷霉素>72%硫酸链霉素>20%噻菌铜,3%噻霉酮的有效中浓度(EC50)为9.401μg·m L-1。
In order to prevent and control tobacco wildfire disease more effectively, the tobacco leaves samples with typical symptoms of wildfire collected from the flue-cured tobacco planting area of Yibin City were isolated, cultured and observed morphologically. The pathogenicity of the isolates was determined by acupuncture combined with needle-less injection inoculation. The pathogenicity of the strains pv-xs-y-2 (strong), pv-xt-y-2 ) And pv-gy-y-1 (weak) and four kinds of fungicides on the virulence of the strain pv-xs-y-2 indoor inhibitory effect. The results showed that the morphological characteristics of 14 strains were consistent with the morphological characteristics of tobacco wildfire, but the pathogenicity of each strain was significantly different. The average disease index was 23.33 ~ 72.22. The results of cluster analysis showed that the pathogenicity of the 14 isolates was strong (disease index ranged from 60 to 72.22), medium (disease ranged from 34.44 to 53.33) and weak (disease ranged to 23.33) 3 Species, of which the type of intermediate pathogenic strains of the main test strains accounted for 71.43%. Under the conditions of artificial cultivation, the optimal temperature for pathogen growth was 28 ℃. The OD600 of pv-xs-y-2, pv-xt-y-2 and pv-gy-y-1 strains were 1.285, 1.105 and 0.977 The OD600 values of pv-xs-y-2, pv-xt-y-2 and pv-gy-y-1 were 0.694, 0.555 and 0.505 respectively. The optimum p H value was 7 , Indicating wildfire suitable for growth in a neutral environment. The results of indoor toxicity test of different medicaments against wildfire were as follows: 3% thiabendazole> 4% kasugamycin> 72% streptomycin sulfate> 20% thiabendazole and 3% 9.401 μg · m L-1.