拮抗细菌的定殖、浓度和喷施期与水稻纹枯病的关系

Relationship between the Colonization,Concentration and Spray Timing of Antagonistic Bacteria and Sheath Blight of Rice

研究两个拮抗细菌Ｐｓｅｕｄｏｍｏｎａｓｃｅｐａｃｉａ（Ｐ－６８５４）和Ｂａｃｉｌｕｓｓｕｂｔｉｌｉｓ（Ｂ－９１６）在水稻植株上的定殖情况。Ｐ－６８５４和Ｂ－９１６菌株用利福平进行抗药性诱导后用于检测。分别在喷施拮抗细菌后２小时及１天、３天、６天、１０天和１５天，分离检测水稻植株表面的拮抗细菌群落。试验结果表明：拮抗细菌的定殖能力与最初引进拮抗细菌的浓度和水稻植株上有无纹枯病病斑有关。当被引进拮抗细菌的浓度较低（Ｂ－９１６为１０６ＣＦＵ／ｍｌ，Ｐ－６８５４为１０７ＣＦＵ／ｍｌ）和喷施在健株上时，不易在植株表面定殖；当被引进拮抗细菌浓度较高（Ｂ－９１６１０１０ＣＦＵ／ｍｌ，Ｐ－６８５４为１０１１ＣＦＵ／ｍｌ）和喷施在病株上时，定殖能力较强。在引进后１５天，在病株上仍能分离到１０３ＣＦＵ／ｃｍ２的Ｂ－９１６和５×１０４ＣＦＵ／ｃｍ２的Ｐ－６８５４。喷施拮抗细菌的最佳时期为接种病原菌Ｒ．ｓｏｌａｎｉ后第１天，最初引进拮抗细菌的有效浓度不能低于１０８ＣＦＵ／ｍｌ。

The colonization of two antagonistic bacterium strains on rice plant surface was studied.The two strains, Pseudomonas cepacia (P 6854) and Bacillus subtilis (B 916), antagonistic to sheath blight of rice, were induced to be rifampicin resistant and used for monitoring. The antagonistic bacterial population on the rice plant surface were isolated and counted at 2 hours and 1,3,6,10 and 15 days after introducing the bacteria.The results of the test showed that the colonization of the antagonistic bacteria was related to the introduced bacterial concentration and sheath bliight lesions on the rice plant.Antagonistic bacteria introduced at low concentrations (10 6 CFU/ml of B 916 and 10 7 CFU/ml of P 6854) and sprayed on healthy plants could hardly grow on rice plant surface; while introduced at high concentrations(10 10 CFU/ml of B 916 and 10 11 CFU/ml of P 6854) and sprayed on rice plant with sheath blight lesions, the population of the antagonistic bacteria could maintain at more than 10 3 CFU/cm 2 of B 916 and 5×10 4 CFU/cm 2 of P 6854 on diseased plants at 15 days after introduction.The results indicate that the appropriate timing to spray antagonistic bacteria is one day after inoculating R.solani and the initial concentration of introduced antagonistic bacteria can not be lower than 10 8 CFU/ml.