钙对两种病原菌引起西洋参根腐病的抑制作用

The Inhibition of calcium on root rot disease of American ginseng caused by two pathogens

由多种病原菌引起的西洋参根腐病是西洋参最主要的地下病害,严重降低西洋参的产量和质量。为了减少农药使用,探究营养元素钙对西洋参根腐病的防治作用及可能的生理生态机制,本研究设置田间盆栽试验,以引起西洋参根腐病的2种病原菌Fusarium solani和Ilyonectria mors-panacis为研究对象,测定不同添加量的氧化钙(0、0.5、1.5和4.5 g·kg^(-1))对西洋参根生长发育的影响和对病害的防治效果,以及对根内营养元素、土壤理化性质、土壤微生物群落的影响。结果表明:添加钙对西洋参根腐病的作用出现“低促高抑”的现象。与对照相比,土壤中添加氧化钙达到4.5 g·kg^(-1)时,接种I.mors-panacis、F.solani引起的根腐病病情指数分别降低87.69%(P<0.05)、66.67%(P>0.05),此时根内钙含量分别提高101.28%和61.50%(P<0.05),根内氮磷含量与接种F.solani组病情指数呈正相关。接种2种病原菌的土壤微生物群落结构及组成存在明显差异。钙主要影响土壤真菌多样性及群落组成,高钙(4.5 g·kg^(-1))情况下亚隔孢壳属(Didymella)、茎点霉属(Pho-ma)的相对丰度均降低;而钙对细菌群落影响较小。综上,高剂量钙可以降低西洋参根腐病65%以上,其潜在的机制与增加根内钙含量、降低氮、磷含量以及减少土壤中潜在病原菌属的相对丰度有关。研究结果将为合理施用钙肥减轻西洋参根腐病提供理论依据。

The root rot caused by Fusarium and Ilyonectria is the most serious disease in American ginseng.The prevention of this disease mainly relies on the utilization of fungicides.However,it is unknown whether it could be controlled by calcium fertilizer.In order to reduce the use of pesticides and find possible physiological and ecological mechanisms of calcium in root rot disease control,a pot experiment was conducted to investigate the effects of calcium application and inoculation.During the cultivation of ginseng,different amounts of calcium oxide(0、0.5、1.5、4.5 g·kg^(-1))was applied to the soil.The root biomass,disease incidence,root nutrient con-tent,soil physicochemical properties and soil microbial community were measured.The results showed that low calcium additions increased root rot disease index,however,high calcium additions decreased root rot disease index.Compared to the control,adding 4.5 g·kg^(-1)calcium oxide decreased root rot disease index of I.mors-panacis by 87.69%(P<0.05),meanwhile,the root rot disease index of F.solani was reduced by 66.67%(P>0.05).The calcium content in American ginseng roots from the two inoculation groups were increased by 101.28%and 61.50%(P<0.05),respectively.Nitrogen and phosphorus content in the roots were positively cor-related with the root rot disease index of F.solani.On the other hand,the structure and composition of soil microbial communities inoculated with two pathogens differed significantly.The calcium treatment mainly affected the diversity and composition of fungal community,while having little effect on the bacterial commun-ity.Additionally,treatment with 4.5 g·kg^(-1)calcium oxide inhibited the relative abundance of Didymella and Phoma.Overall,the potential mechanism for the reduction of root rot disease in American ginseng by more than 65%through the application of high-dose calcium is related to increased calcium content in roots,reduced nitrogen and phosphorus content in roots,and decreased the relative abundance of potential pathogens in soil.This study provides a theoretical basis for reducing root rot disease of American ginseng through rational application of calcium fertilizer.