3株拮抗菌在水稻植株上的定殖能力及对纹枯病的防效

摘要

【Objective】 The objective of this study was to explore the colonization ability and biocontrol effects of three antagonistic strains NB12（Bacillus sp.）,SD7（Burkholderia sp.）and NB20（Streptomyces katrae）screened by our laboratory on rice sheath blight（RSB） at detached leave,seeding and tillering stage.【Method】 Mutants of strains NB12 and SD7 resistant to rifampin at 300 μg/mL were induced and screened at various concentrations of rifampin,and were used in their colonization study.RSB pathogen Rhizoctonia solani mycelial masses of diameter 5 mm were used as inoculum for inoculation on detached leave test,while rice grains covered with R.solani mycelia were used as inoculum for inoculation at seedling and tillering stages.【Result】 The results indicated that both strains of NB12 and SD7 could colonize on rice leaves at a high density.More than 106 CFU/g labeled strains could be detected after 20 days on mature leaves and labeled strains could be also detected after 10 days on newly-growing leaves.The control effects of strains NB12,SD7 and NB20 on RSB of detached leaves reached 91.3%,90.0% and 54.4%,respectively,significantly higher than that（77.5%） of Jinggangmycin at 40 μg/mL.The three strains showed promising control effect of 59.91%,53.73% and 38.47%,respectively,on RSB at seedling stage and their cell-free fermented filtrates also behaved certain effect.However,all of the three strains showed an unsatisfactory effect at tillering stage,and two better treatments of fermented fluids of NB12 and SD7 just behaved limited control effect of 17.6% and 24.0%,respectively.It was also found that the mixed fermented fluids of strain NB12,SD7 and NB20 could not only raise the control effect,but also lower it.【Conclusion】 Strains NB12 and SD7 behaved promising biocontrol ability to RSB at detached leave test and seedling stage,but the control effect on RSB at tillering stage needs further study.%【目的】研究筛选出的芽孢杆菌（Bacillus sp.）NB12、伯克霍尔德菌（Burkholderiasp.）SD7、卡特拉链霉菌（Streptomyces katrae）NB20在水稻植株上的定殖能力,以及在离体叶片、苗期和分蘖盛期对水稻纹枯病的防治效果。【方法】NB12和SD7两菌株用利福平（Rif）进行抗药性标记,筛选到抗300μg/mL Rif的抗药性菌株用于定殖试验;水稻离体叶片试验用5mm菌丝块接种,苗期和分蘖盛期试验用带菌谷粒接种。【结果】定殖试验结果表明,SD7和NB12菌株在水稻叶片上能以较高密度定殖,第20天仍能检测到106 CFU/g的标记菌株,且10d后在新生叶片中也可检测到标记菌株。在离体叶片试验中,NB12、SD7和NB20发酵菌液对水稻纹枯病的防效分别达到91.3%,90.0%和54.4%,前2个菌株的防效显著高于40μg/mL的井冈霉素（77.5%）。3个菌株对苗期水稻纹枯病也有较好的防治效果,其发酵菌液防效依次为59.91%,53.73%和38.47%,其无菌滤液也有一定防效。3个菌株对分蘖盛期水稻纹枯病的防治效果不理想,表现较好的NB12发酵菌液和SD7发酵菌液防效也只有17.6%和24.0%,低于井冈霉素的防效（32.9%）。试验中发现,3个菌株的混合处理并没有提高防治效果,反而降低了防效。【结论】NB12和SD7两菌株对水稻离体叶片和苗期纹枯病表现了良好的生防能力,其对分蘖盛期水稻纹枯病的防治效果还需要进一步研究。