Kannangara T, Utkhede R S, Paul J W, Punja Z K
Pacific Agri-Food Research Centre, Agassiz, BC, Canada.
Can J Microbiol. 2000 Nov;46(11):1021-8. doi: 10.1139/w00-082.
Three composts were tested for their ability to suppress root and stem rot caused by the soil borne fungal pathogen Fusarium oxysporum f. sp. radicis-cucumerinum (FORC) on cucumber. Two of the composts were prepared from separated dairy solids either by windrow (WDS) or vermicomposting (VMC) while the third, obtained from International Bio-Recovery (IBR), was prepared from vegetable refuse using aerobic digestion. Three sets of potting mixes were prepared by mixing the composts with sawdust at varying ratios, and seeded with cucumber cv. Corona. After 14 days of growth in the greenhouse, inoculum of FORC (20 mL of 5 x 10(6) micro-conidia per mL) was applied to each pot at three different times (14, 21, and 35 days). In unamended inoculated pots, the pathogen caused stunted growth and reduced flowers. Amendment of WDS in the potting mix suppressed these symptoms, while VMC and IBR had no effect. All three composts reduced the FORC colony forming units (cfu) at the end of the experiment (10 weeks). There was a large increase of fluorescent bacteria near the vicinity of roots particularly in WDS amended potting mixes. When water extracts of the composts were plated onto acidified potato dextrose agar (APDA), only IBR contained a potent thermostable inhibitor to FORC. This inhibitor was removed by activated charcoal but was not partitioned into petroleum ether at acid, basic, or neutral pH. Inhibition of FORC by IBR was not due to electrical conductivity or trace elements in the compost. Contrasting effectiveness of the WDS and VMC made from the same waste suggests that composting method can influence the disease suppression properties of the finished compost.
测试了三种堆肥抑制黄瓜由土壤传播真菌病原体尖孢镰刀菌黄瓜根腐专化型（FORC）引起的根腐病和茎腐病的能力。其中两种堆肥由分离的乳制品固体通过条垛堆肥（WDS）或蚯蚓堆肥（VMC）制备，而第三种从国际生物回收公司（IBR）获得，由蔬菜废弃物通过好氧消化制备。通过将堆肥与锯末按不同比例混合制备了三组盆栽基质，并播种黄瓜品种科罗纳。在温室中生长14天后，在三个不同时间（14、21和35天）向每个花盆施加FORC接种物（每毫升含5×10⁶个微分生孢子的20毫升）。在未改良的接种花盆中，病原体导致生长发育迟缓并减少花朵数量。盆栽基质中添加WDS可抑制这些症状，而VMC和IBR则没有效果。在实验结束时（10周），所有三种堆肥都减少了FORC菌落形成单位（cfu）。在根附近荧光细菌大量增加，特别是在添加WDS的盆栽基质中。当将堆肥的水提取物接种到酸化马铃薯葡萄糖琼脂（APDA）上时，只有IBR含有对FORC有效的热稳定抑制剂。该抑制剂可被活性炭去除，但在酸性、碱性或中性pH条件下不会分配到石油醚中。IBR对FORC的抑制作用不是由于堆肥中的电导率或微量元素。由相同废弃物制成的WDS和VMC的不同效果表明，堆肥方法可以影响成品堆肥的病害抑制特性。
