枯草芽孢杆菌B-332菌株对稻瘟病的防治效果及定殖作用

为了进一步明确枯草芽孢杆菌B-332菌株对稻瘟病的生防作用,分别对盆栽水稻的防治效果、防治适期、标记菌株在水稻上的定殖作用及田间的防治效果进行了考察。结果表明,在盆栽水稻活体生物测定中,B-332的芽孢菌体悬浮液及发酵上清液对稻瘟病均表现出较好的防治效果(50%以上),且当菌液与上清液混合后其防治效果有加和作用。该菌株对稻瘟病的防治作用主要体现在预防,其预防叶瘟的效果与接种稻瘟病菌时叶面已定殖的B-332菌株的数量有关,接种时水稻叶面上定殖的菌量为1.25×104cfu/mm2时,其防治效果可以达到45%。在人工大量引入的情况下,该菌能够在水稻叶面上有效定殖达21天以上,并且在叶面有10%病斑的情况下,检测到的标记菌株数量会更多。田间试验结果表明,芽孢浓度在1×108cfu/mL时,该菌株对水稻穗颈瘟的防治效果达57.2%,增产率达9.6%,且浓度在5×108cfu/mL时对螃蟹无毒性。

Biological control of rice blast by Bacillus subtilis B-332 strain

To confirm the control efficacy of rice blast by Bacillus subtilis B-332 strain, the control efficacies of pot experiments, the control effect of different occasions, the colonization of B-332 on rice leaves and the control effect in field trials were investigated respectively. In pot plant experiments, B-332 strain and its culture supernatant showed significant control efficacies (over 50%) against rice blast, and the control efficacy of admixture of them was much better. The control efficacies were mainly contributed by preventing activity other than curative activity. The preventing efficacy is depending on the density of colonized B-332 strain on the rice leaves surface when inoculating the spores of M.grisea. The B-332 strain could colonize on rice leaves surface after introducing, and can be isolated 21 days later. The more population of B-332 strain could survive on the leaf with 10% infection lesions. In field trial, the control efficacy of rice panicle blast was 57.2%, increasing yield 9.6% when consistency of B-332 was at 1×10⁸ cfu/mL, and have no toxicity to crabs even at 5×10⁸ cfu/mL.