土壤强还原过程产生的有机酸对土传病原菌的抑制作用

土壤强还原(reductive soil disinfestation,RSD)能有效杀灭土传病原菌,并已在日本、荷兰和美国取得一系列的推广应用,但对于RSD的杀菌机理不甚明了。本试验采用高效液相色谱和荧光定量PCR等技术研究了以玉米秸秆为有机碳源的RSD处理过程中土壤产生的有机酸种类,以及不同浓度的有机酸对土壤病原菌的抑制效果。结果表明:以玉米秸秆为有机碳源的RSD过程中主要产生了乙酸和丁酸;经50mmol/L丁酸溶液处理的土壤中立枯丝核菌、辣椒疫霉、尖孢镰刀菌及茄劳尔氏菌的数量分别为对照的3.5%、38.9%、11.5%和7.9%;10mmol/L的丁酸可以完全抑制尖孢镰刀菌菌丝的生长;5mmol/L的丁酸即可完全抑制尖孢镰刀菌的孢子萌发。本研究结合前人报道表明有机酸,尤其是乙酸和丁酸,对于RSD的杀菌机理起着重要的作用。

Inhibitory effects of organic acids produced in reductive soil disinfestation on soil borne plant pathogens

Reductive soil disinfestation (RSD) is an effective way to suppress soil borne plant pathogens. Although it is increasingly used in USA, Netherlands and Japan, its precise mechanism has not been well elucidated so far. High performance liquid chromatography and quantitative real time PCR were used for investigating the organic acids produced in maize straw amended RSD and the inhibitory effect of organic acids on the soilborne pathogens in this work. The results showed that acetic acid and butyric acid were the primary compounds produced in maize straw amended RSD.The populations of Rhizoctonia solani, Phytophthora capsici, Fusarium oxysporum and Ralstonia solanacearum in the diseased soil treated by 50 mmol/L butyric acid solution decreased by 96.5%, 61.1%, 88.5% and 82.1%, respectively, compared with those in non treated diseased soil. The growth of F. oxysporum mycelium was completely stopped in 1/4 potato dextrose agar medium containing 5 mmol/L butyric acid, and 5 mmol/L butyric acid could entirely inhibit the germination of F. oxysporum spores. This work together with previous reports indicated that organic acids, especially acetic and butyric acid, played an important role in the mechanism of RSD.