Analysis of the Relationship between Soil pH and Clubroo of Mustard

[Objective]The paper was to study the severity of mustard clubtoot under different pH conditions and to clear the relationship between pH and mustard clubroot.[Method] Totally 288 soil samples were collected from the infected patches of clubroot in Fuling District,Chongqing City,and their pH were measured.Meanwhile,the germination rate of resting spores,the incidence rate of clubroot and vegetative growth of mustard was measured under different pH conditions,to figure out the relationship between pH and mustard clubroot.[Result] The pH of 288 pathogenic soil samples distributed from 4.0 to 7.0.The germination rates of resting spores were higher than 50% when the pH was 5.0-6.5,and the germination rates were low when the pH was 3.0,4.0,8.0,8.5,9.0 and 10.0.Greenhouse pot test showed that the incidence rate of mustard clubroot in acidic environment was higher than that in alkaline environment.The incidence of mustard clubroot was severe when the pH was 4.5-6.5; the incidence was the severest at the pH of 6.0,and the disease index reached 84.22; mustard was not attacked by clubroot at the pH of 8.0.Measurement results of various growth indicators of mustard under different pH conditions demonstrated that mustard had better growth at the pH of 5.0-7.5,and the growth was the best at the pH of 6.5,while the growth was suppressed at the pH of 4.0 and 8.0.[Conclusion]Clubroot of mustard is likely to happen under weak acidic condition.The suitable pH for the vegetative growth of mustard is 5.0-7.5.