温室条件下拮抗细菌Bacillus subtilis B5423-R对水稻纹枯病水平扩展和垂直扩展的抑制

Suppressive Effect of Bacillus Subtilis B5423-R on the Horizontal and Vertical Spread of Rice Sheath Blight under Greenhouse Conditions

BacillussubtilisB5 42 3对水稻纹枯病的抑制作用主要是通过其产生的拮抗素。在温室条件下 ,于水稻分蘖盛期接种纹枯病菌Rhizoctoniasolani,并采用 2d喷 1次、不同次数对单株喷雾B5 42 3 -R(B5 42 3的标记菌株 ,是利福平抗性的突变体 )的方法进行试验 (对纹枯病水平扩展的抑制 ) ;类似地 ,采用 2d喷 1次、不同次数对小区内所有稻株喷雾B5 42 3 -R的方法进行试验 (对纹枯病垂直扩展的抑制 )。结果表明 1～ 2次喷雾未能显著地降低蚊枯病病丛率和相对病斑高度 ,而连续 3次喷雾使B5 42 3 -R在稻株的群体数量于纹枯病侵染的早期即最初的 6～ 7d内维持在 1× 1 0 6cfu/g以上 ,显著地降低了病丛率和相对病斑高度。

The mechanism of Bacillus subtilis B5423 in suppressing rice sheath blight is mainly from the antibiotics produced by itself. The experiment of B5423-R (marking strain of B5423, a Rifampicin-resistant mutant) suppressing horizontal spread of rice sheath blight was conducted by inoculating Rhizoctonia solani into a single plant, and spraying B5423-R at different times to the single plant under greenhouse conditions. Similiarly, the experiment of B5423-R suppressing vertical spread of sheath blight was carried out by inoculating R.solani and spraying B5423-R at different times to all plants within a treatment. The results demonstrated that successive spraying of B5423-R 3 times with an interval of 1 day maintained population sizes of B5423-R on rice stems more than 1×10 6 cfu/g within early 6～7 days, which resulted in significant reduction of diseased hill percentage and relative lesion height.