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为查明春烟换茬后青枯菌在土壤中的消长规律,采用接种耐药性青枯菌的盆土种植烟草,烟草枯死后种植不同轮作作物的方法,研究不同作物对土壤中青枯菌数量及其越冬状况的影响。设茄子、大豆、花生、甘薯、大蒜、玉米、晚稻和双季稻8个轮作物处理,后作生长期间定期取样,用含利福平的选择性培养基检测样品中的青枯菌数量。结果表明,栽后第4周起秋茄子和秋大豆根中皆测出青枯菌,秋茄子根达106 cfu·g-1;晚稻和秋花生根只第2周和第8周测出带菌。秋茄子、秋大豆、秋花生和晚甘薯生长期间土壤皆测出青枯菌,数量先降后升至104～106 cfu·g-1;晚稻和秋玉米土壤中青枯菌数量持续下降;大蒜处理先测出带菌后未测到。冬季对水稻残桩青枯菌数量监测显示,稻桩根和土壤中青枯菌数量先后出现峰值,分别达1.00×105 cfu·g-1和5.17×104 cfu·g-1;发现病菌能在稻根变黑腐烂时增殖。翌年春季从茄子、大豆、花生和甘薯茬口土壤中测出遗留青枯菌数量皆达104 cfu·g-1,玉米为103 cfu·g-1。烟草移栽后青枯病调查表明,不同处理发病迟早取决于茬口土壤中菌源数量,两者相关系数r为0.908 9。不同茬口土壤发病轻重有显著差异,茄子茬土发病最重,病情指数100,大豆和大蒜茬土发病略重于花生、甘薯和玉米茬土;晚稻茬土发病最轻,病情指数16.7,与茄子茬土相比发病期推迟20 d,病情指数下降83.3%;双季稻茬土未见发病,证明烟稻轮作对青枯病有较好的控制效果。
In order to find out the growth and decline of R. solanacearum in the soil after spring stubble replacement, the tobacco plants were planted with potting plants resistant to R. solanacearum and the crops were planted after the dead tobacco. Influence of the number of bacteria and their overwintering condition. Eggplant, soybean, peanut, sweet potato, garlic, corn, late rice and double cropping rice were planted for 8 rounds and then regularly sampled during the growth period. The amount of Ralstonia solanacearum in the sample was measured with a selective medium containing rifampicin. The results showed that Ralstonia solanacearum was detected in the roots of autumn and autumn soaps from the fourth week after transplanting. The root of autumn fall eggplant was 106 cfu · g-1. The second and the eighth week of late rice and autumn peanut roots were detected with fungi. Ralstonia solanacearum was detected in soils during autumn, autumn, autumn and late sweet potato growth. The number of Ralstonia solanacearum first decreased to 104 ~ 106 cfu · g-1 and the number of Ralstonia solanacearum continued to decline in late rice and autumn corn. No measurable after the first test detected. In winter, the quantity of R. solanacearum was monitored, and the number of R. solanacearum reached the peak of 1.00 × 105 cfu · g-1 and 5.17 × 104 cfu · g-1, respectively. Proliferation of rice roots rotting black. In the following spring, the number of remaining R. solanacearum was 104 cfu · g-1 and that of maize was 103 cfu · g-1 in soils of eggplant, soybean, peanut and sweet potato stubble. Investigation of bacterial wilt after tobacco transplanting showed that the morbidity of different treatments depends on the quantity of bacteria in the stubble soil, and the correlation coefficient r between them is 0.908 9. Soil disease incidence of different stubble significantly different, eggplant stubble soil the most serious disease index of 100, soybean and garlic stubble soil slightly heavier than peanut, sweet potato and corn stubble soil; late rice stubble soil lightest disease index 16.7, and eggplant Compared with the period of onset of soil stubble delayed 20 d, the disease index decreased by 83.3%; double cropped rice stubble soil no incidence, proved that tobacco rotation has a better control effect on bacterial wilt.