Effects Of Continuous Cropping Years On The Growth Of Codonopsis Pilosula,Soil Physical And Chemical Properties And Enzyme Activities

Codonopsis Pilosula continuous cropping obstacles has been an important factor restricting the development of its industry.In order to investigate the effects of continuous cropping years of Codonopsis Pilosula on growth indexes,physical and chemical properties of soil,morbidity,yield and quality,this paper takes different continuous cropping years(1a,2a,3a,4a)of Codonopsis Pilosula in Tanchang County,Gansu Province as the research object,analyzed the effects of continuous cropping years on the growth indexes(length of Codonopsis pilosula vine and root;diameter,dry weight and fresh weight of root)of different continuous cropping years,and soils physical and chemical properties(soil organic carbon,total phosphorus,total nitrogen,available phosphorus,available potassium,conductivity,p H)and enzyme activity characteristics(soil catalase,urease,sucrase,nitrate reductase,alkaline phosphatase)of different soil layers in different growth periods,the incidence of main diseases,yield and quality.The results show that:(1)Effect on growth index of Codonopsis pilosula: The vine length and length,diameter,dry weight,fresh weight of root of Codonopsis pilosula decreased with the increase of continuous cropping years,but the indexes did not show significant difference in seedling and flowering period;the continuous cropping years had significant influence on the root length,dry weight and fresh weight of Codonopsis pilosula in vigorous growth and harvest period.(2)Effects on the physical and chemical properties of soil : The content of organic carbon,total phosphorus,total nitrogen and available phosphorus in the soil of Codonopsis pilosula increased first and then decreased with the increase of continuous cropping years.The soil layer had no significant effect on the physical and chemical properties of the soil;Except for the seedling stage,the soil available potassium of Codonopsis pilosula increased with the increase of continuous cropping years in each growth stages;The soil conductivity of Codonopsis pilosula had no significant difference between different soil layers,but it generally increased with the increase of continuous cropping years;the p H of Codonopsis pilosula soil generally increased with the increase of continuous cropping years,but the range of change is small.(3)Effects on soil enzyme activity: With the increase of continuous cropping years,the activity of catalase of Codonopsis pilosula showed a continuous decline trend,there was no significant difference between the continuous cropping years;With the increase of continuous cropping years,the soil urease,nitrate reductase activity showed an overall trend of first rising,then declining and then rising,and there were significant differences between each continuous cropping years.(4)Effects on the incidence rate of main diseases : With the increase of continuous cropping years,the incidence rate of main stem,leaf and root diseases of Codonopsis pilosula increased continuously,and there was significant difference in different continuous cropping years.(5)Effects on the yield and quality: With the increase of continuous cropping years,the yield of Codonopsis pilosula continuously decrease,and the difference in continuous cropping years reached a significant level;The long-term continuous cropping results in the continuous reduction of the quality of Codonopsis pilosula.With the increase of continuous cropping years,the first-class and second-class products show a trend of decreasing year by year,while the third-class and worse show a trend of increasing year by year;Although there is no significant difference in the water content of Codonopsis pilosula in different continuous cropping years,the general trend of decreasing first and then increasing is shown.When the continuous cropping reaches 4a,the ash content of Codonopsis pilosula is significantly higher than that in other years.(6)The contents of organic carbon and available potassium in the physical and chemical properties indexes of soil are the main factors affecting the yield.The urease and alkaline phosphatase activities in the soil enzyme activity indexes are the main factors affecting the yield.The main diseases of Codonopsis pilosula are the main factors affecting the yield.Carbon and available phosphorus had the greatest impact on the yield of Codonopsis,while soil organic carbon,total phosphorus and available potassium had the greatest impact on the quality of Codonopsis.