| Rehmannia glutinosa Libosch.is a Perennial officinal of Scrq Phulariaceae,a famous one of the "four Huaiyao",dried root is used as medicine.It it the traditional Chinese medicine.R.glutinosa is one of the most serious medicinal plants in the continuous cropping obstacles of the root tuber,which must be separated for 8-10 years after the harvest and seriously restrict the production and development.In this paper,"Wen 85-5" as the test material,the rhizosphere of R.glutinosa soil as the research object,the method of combining field experiment with laboratory analysis was adopted.Study on the effect of different continuous cropping years of R.glutinosa on the growth and physiological and the content of root tuber.We also studied whether the effective chemical components of R.glutinosa root was secreted into the soil by HPLC.At the same time,the content of phenolic allelochemicals in soil of different continuous cropping years of R.glutinosa was determined.The allelopathicals potential of each section was analyzed by seeds generation and pot experiment.The main conclusions are as follows:(1)Along with the increasing years of continuous cropping,the mortality of R.glutinosa were increased first and decreased later,the leaf area and crown area,above ground and underground parts of the fresh and dry weight of R.glutinosa were decreased first and increased later,but the emergence rate and the number of leaves did not have this trend.The replanted R.glutinosa underground root on fresh and dry weight were lowest,3 years of continuous cropping R.glutinosa leaves on the fresh and dry weight were the lowest.There was a difference between aboveground and underground of continuous cropping R.glutinosa.In the early part,the underground has been shown the continuous cropping obstacles,while the aboveground fall behind the underground part to the middle of the growth period was gradually revealed.(2)With the increase of continuous cropping years,the chlorophyll and relative electrical conductivity showed a process of rising and then decreasing,but had a different change trend with SOD,POD,CAT.At the same time,replanted and 3 yearsof continuous cropping R.glutinosa showed a worst performance on physiological characteristics,but had a good trend on it with increase years of continuous cropping.(3)With the increase of continuous cropping years,the yield and content of the root tuber of catalpol and verbascoside showed a decreased first and then increased process.The yield and content of catalpol and verbascoside of replanted R.glutinosa were the lowest,only 35.14%,8.62% and 30%,8.59% of normal.Continuous cropping decreased the content of R.glutinosa,which affected the quality of it.With the increase of continuous cropping years,the quality of R.glutinosa had a trend of slow recovery.(4)There were not detected of catalpol and verbascoside and other 6 kinds of components of rhizosphere soil of R.glutinosa by HPLC,which indicate that the effective medicinal ingredients in root tuber of R.glutinosa are less or have been degraded when tested.(5)There were detecting 5 kinds of phenolic acid in different continuous cropping years of rhizosphere soil of R.glutinosa.With the increase of continuous cropping years,the content of phenolic acids in soil increased first and then decreased gradually.The total content of 5 kinds of phenolic acids was the highest in the soil of continuous cropping for 3 years.The different continuous cropping years of R.glutinosa extracts had inhibited on the germination and growth of lettuce seeds.The higher the concentration of soil extracts,the more significant inhibition.The RI values of the soil extract were the lowest at each concentration of 3 years of continuous cropping and replanted R.glutinosa,indicating that the lettuce seed roots had the strongest inhibitory effect.(6)There was a negative correlation between the total phenolic acid content and the 5 kinds of phenolic acid in the soil of different continuous cropping years and the growth and physiological indexes of R.glutinosa,and the higher the phenolic acid content,the lower the physiological index of the growth of R.glutinosa.At the same time,there is a certain correlation between the physiological indexes of R.glutinosa.The physiological indexes of R.glutinosa have more influence on the quality of R.glutinosa. |
