The Inhibition of calcium on root rot disease of American ginseng caused by two pathogens
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-1calcium 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.
calciumAmerican ginseng root rotFusarium solaniIlyonectria mors-panacismineral nutrientssoil microbial community