| Salvia miltiorrhiza Bunge is a perennial herb of the genus Salvia of the Lamiaceae family.It is one of the bulk medicinal material commonly used in China,which has the function of promoting blood circulation and menstrual pain relief.It has a wide distribution range and a long history of cultivation in major production areas such as Shandong,Henan,Shanxi and Sichuan.There are serious continuous cropping obstacles in the cultivation process,and the annual “one site,one year” planting model is not suitable,which is not conducive to the development of S.miltiorrhiza industry towards modern facility agriculture.S.miltiorrhiza which produced in Sichuan,is also called Chuan Danshen,and its roots are characterized by thick meat and low lignification.In the cultivation process,the main production area of it in Zhongjiang county is affected by continuous cropping obstacles.The land required 2-3years of rotation,as a result,the area of S.miltiorrhiza is insufficient,the yield and quality are unstable,and standardized cultivation can not be carried out.In recent years,with the development of Sichuan pharmaceutical industry,the planting area of S.miltiorrhiza has been expanding.It is an important to explore the causes of continuous cropping obstacles of S.miltiorrhiza and find effective ways to alleviate them.Therefore,this study explores the effects of the continuous cropping obstacles on S.miltiorrhiza plants and rhizosphere soil analysis to provide a theoretical basis for the reasonable solution of continuous cropping obstacles.The results are as follows:1.Effects of continuous cropping on plants of S.miltiorrhiza from Sichuan:The rate of emergence of S.miltiorrhiza from Sichuan decreased and the rate of withered seedlings increased;plant height,root length,root diameter and root number decreased significantly(P <0.05).Root vitality of S.miltiorrhiza decreased by 20%,42%and 41% respectively after continuous cropping,the total chlorophyll content of the plants after continuous cropping decreased significantly(P<0.05);The activity of SOD,POD,CAT increased significantly(P<0.05),MDA content increased significantly(P <0.05).Planting in the first year,the average fresh weight per plant was 582 g/plant,and the average dry weight was 230 g/plant.The fresh weight decreased by 21%,68%,and 70%respectively in continuous cropping 1,2,and 3 years;the dry weight decreased.26%,73%,72%(P <0.05)respectively;There was no significant difference in fresh weight and dry weight per plant between 2 and 3 years of continuous cropping(P> 0.05).The content of phenolic acid components decreased,and the content of salvianolicacid B was 8.64% in the first year,and 6.39% for 3 years of continuous cropping;the content of ketone components increased,and the content of tanshinone IIA in the first year was 0.22%,for 3years of continuous cropping was 0.40%.2.Effects of continuous cropping on soil:After continuous cropping,the soil p H decreased,the soil was weakly acidified,the soil organic matter was significantly reduced(P<0.05),the soil water content was significantly increased(P<0.05),and the utilization rate of soil nutrients decreased,and the available N,P,and K in the soil were higher than that in the first year.The activities of acid phosphatase,urease,and sucrase in soil hydrolase decreased significantly,polyphenol oxidase activity increased in oxidoreductase,and catalase activity decreased.The main types of compound in continuous cropping soil are acids,hydrocarbons,alcohols,esters,ketones,and aldehydes.Among them,the straight-chain alcohols(3,7,11-trimethyl-1-dodecanol,1-octadecanol,1-hexadecanol,behenic alcohol,1-butanol)and phenolic acids(2,4-di-tert-butylphenol,methyltartronic acid,muramic acid,hydroxyacetic acid),hexadecanoic acid butyl ester,phthalic acid butyl tetradecyl ester,bis(2-ethylhexyl)phthalate have allelopathic effects in the continuous cropping obstacles. |
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