发生和未发生连作芦蒿枯萎病土壤的尖孢镰刀菌数量、产毒能力和致病力

Population, toxicity and pathogenicity of Fusarium oxysporum in continuously cropped soil of Artemisia selengens with or without Fusarium wilt

尖孢镰刀菌引起的枯萎病是芦蒿连作障碍主要病害.对芦蒿不同种植年限发病和未发病土壤中尖孢镰刀菌数量、产毒素(镰刀菌酸)能力、致病力等开展研究.对采集的11份土壤样品分析结果显示:相较于不发病土壤,发病率≥40%的土壤尖孢镰刀菌数量显著增加;不发病和发病率≤25%的土壤尖孢镰刀菌数量没有显著差异(P>0.05).发病率为85%和40%的土壤尖孢镰刀菌高产毒素(镰刀菌酸产量>500μg L-1)的菌株比例显著(P<0.05)高于发病率为11%和不发病土壤.致病力测定显示发病率为85%和40%土壤中高致病力菌株比例显著(P<0.05)高于发病率为11%的土壤和不发病土壤,不致病菌株比例显著(P<0.05)低于发病率为11%的土壤和不发病土壤.土壤尖孢镰刀菌数量与连作年限没有显著相关性(P>0.05).发病土壤中,发病率、尖孢镰刀菌高产毒素菌株比例和高致病力菌株(病情指数>2)比例与连作年限显著(P<0.05)相关;未发病土壤中,尖孢镰刀菌高产毒素菌株比例和高致病力菌株比例与连作年限没有显著相关性(P>0.05).随着连作芦蒿发病率的增加,土壤中尖孢镰刀菌菌株数量、高产毒素菌株比例、致病菌株比例均显著增加(P<0.05),未发病连作土壤尖孢镰刀菌菌株数量、高产毒素菌株比例、致病菌株比例均没有显著变化.本研究结果可为连作芦蒿枯萎病发病机理的研究及其防治提供理论基础.

Fusarium wilt caused by Fusarium oxysporum （FO） is the major disease in continuously cropped Artemisiaselengens. This research investigated the population, toxicity （production of fusaric acid） and pathogenicity of FO in the continuously cropped soil ofArtemisia selengens with or without Fusarium wilt. The results showed that FO population in the soils with 40% or more disease incidence of Fusarium wilt was significantly higher than that in soil without disease （P 〈 0.05）. FO population in the soils with 25% or lower disease incidence was not significantly different from the control （P 〉 0.05）. Percentages of FO with high toxicity （yield of Fusarium acid 〉 500 μg L1） were higher （P 〈 0.05） in soil with Fusarium wilt of 85% and 40% than in soil with Fusarium wilt of 11% or without disease. The same trend was found in the pathogenicity of FO. Populations of FO in the continuously cropped soil were not significantly correlated with the years of continuous cropping. Disease incidence, percentages of FO with high toxicity and high pathogenicity （disease index 〉 2） were significantly correlated with years of continuous cropping in the soil with high incidence of Fusarium wilt, but not in soil without disease. In the continuously cropped soils of higher disease incidence of Fusarium wilt, the population of FO, percentages of FO with high toxicity and high pathogenicity were also significantly higher （P 〈 0.05） compared to the continuously cropped soil without Fusarium wilt. In the soil without Fusarium wilt, no significant relationship was found between continuous cropping yearsand the population of FO, percentages of FO with high toxicity and high pathogenicity （P 〉 0.05）. The results offer a basis for further study of the mechanism of Fusarium wilt in continuously cropped soil and the biocontrol of the disease.