Effects Of Mineral Elements On Growth And Quality Of American Ginseng

The dried root of American ginseng（Panax quinquefolius L.）is a widely used tonic traditional Chinese medicine.It can invigorate Qi and nourish Yin,clear heat and promote fluid production.American ginseng was introduced successfully in the early 1980s and planted in large area Jilin and Shandong province in China.American ginseng is mainly planted by individuals for a long time.A standard cultivation technology system has not formed.Mineral elements are the basis of ensuring crop yield and quality.It was found that blind fertilization,serious disease,uneven yield and quality were common in the cultivation and production of American ginseng.American ginseng is a perennial medicinal plant.Although there were some researches on nutrition and fertilization in the past,they were not systematic enough and lack of understanding of mineral elements demand in the whole planting process.Therefore,the demand of large and trace elements of American ginseng was studied.The purpose of this study is to provide reference for scientific and reasonable fertilization,disease reduction,yield and quality improvement of American ginseng.The main results are as follows:1.Effects of nutrients deficiency on growth and saponin accumulation of American ginsengThe 2-year-old American ginsengs were cultivated by Hoagland solution（CK）or 10 different nutrients deficiency solution in sand culture.During the cultivation,the deficient symptom was observed.The plant height,leaf area,biomass,photosynthetic index,root activity,ginsenoside content were measured.The results showed that N,K or Fe deficiency could lead to leaves of American ginseng yellowing.Deficiency N,K,Ca,Mg and B were the main factors that decrease plant height and leaf area.The biomass of plant decreased significantly in all the nutrient deficient treatments（P<0.05）compared with control group,and N,K,Ca or Fe deficiency groups have descend over 50%.In the absence of N,K and Fe elements,the Pn,Gs,Ci,Tr and Chlorophyll of leaves were decreased most.The first three factors decreasing root activity were N,K and Ca deficiency.The effects of nutrient deficiency on saponins of American ginseng were different.Generally,N,P,B,Zn and Cu deficiency resulted the synthesis of saponins decreased significantly（P<0.05）.This study contributed to clarify the demand characteristics of American ginseng for different nutrient elements,which is of great significance for the diagnose of nutrient deficiency,the rational fertilizer and the improvement of yield and quality of American ginseng.2.Material accumulation of 1-4 years American ginsengAmerican ginseng of 1-4 years different growing season were collected in Wendeng District,Weihai City,Shandong Province.The dry matter and ginsenoside content of roots at different growth stages were determined.The results showed that the dry matter accumulation of American ginseng increased gradually in each growing season.In the first year,the proportion of aboveground part was larger than that of root in the second to the fourth year.The accumulation was the fastest in the later growth period in the first year.,The accumulation was the fastest in the early growth stage in the second year.The accumulation of the third and the fourth year is the fastest in the middle stage（flowering stage fruiting stage）.The contents of Re,Rb1,Rb2 and Rd gradually increased with the growth years.The change of Rc and Rg1 is not significant.In the third and fourth year,the content of total saponins reached the highest in the root expansion stage.The accumulation rate of total saponins in the first and second year was not significant in the growth period.And the accumulation rate of total saponins in the third and fourth year was the fastest in the middle period.3.Absorption characteristics of mineral elements in 1-4 years American ginseng plants and their correlation with dry matter and saponinsDetermination of N,P,K,Ca,Mg,Fe,Mn,Cu,Zn,B elements in Panax quinquefolium plants of different growth periods.The results showed that the most rapid accumulation of N,P,K,Ca,Mg in 1-4 years American ginseng was mainly in the middle and later stages of growth.The accumulation of trace elements Fe,Cu,Zn,B was the fastest in the middle stage（flowering stage fruiting stage）.The most rapid accumulation period of Mn was in the early stage（leaf developing stage flowering stage）.The accumulation of 10 mineral elements was positively correlated with the accumulation of dry matter and saponin respectively（P<0.01）.The production efficiency of major elements for dry matter and saponin was N>K>Ca>Mg>P.The production efficiency of trace elements for dry matter and saponin was Fe>Mn>Zn>Cu>B.4.Effect of fertilization combination of nitrogen,phosphorus,and potassium on root weight,saponin content and disease index of American ginsengThe 2-year-old American ginseng plants were inoculated with the pathogen（Ⅱyonectria communis）under“3414”different N,P and K fertilizer levels.The root weight and disease index of roots were counted.Saponin content was determined.The effect relationship between root weight,saponin content,disease index and fertilizer was established by regression analysis.The results show that the root weight of N₂P₁K₁ was the highest,which was increased by 51.25%compared with the control without fertilization（N₀P₀K₀）.The saponin content of N₂P₂K₁ was the highest,which was increased by 64.21%compared with N₀P₀K₀.The effect of N₂P₁K₁,N₂P₂K₃ and N₁P₁K₂ on disease index was the most obvious,which was reduced by more than 50%compared with N₀P₀K₀.The best theoretical application amount of N,P or K fertilizer with the highest root weight was 0.19,2.25 and 0.26 g/kg respectively.The effect on root weight was N>K>P.The best theoretical application amount of N or K fertilizer with the highest total saponin content was 0.21 and 0.26 g/kg respectively.The effect on saponin content was K>N.The best theoretical application amount of N or P fertilizer with the lowest disease index was 0.31 and 1.68 g/kg respectively.The effect on disease index was P>N.The interaction effect of fertilizer on root weight and total saponins was NK>PK>NP.The best fertilization ratio was N₂P₂K₂ according to the root weight,saponin content and disease index.5.Quality-based soil fertility quality assessment of American ginseng main production areas in Shandong ProvinceIn order to establish the American ginseng planting soil fertility quality evaluation method based on the effective components of American ginseng,Wendeng district,Weihai city,Shandong Province,the main producing area of American ginseng,was cited as a case for the study.Twenty-two 4-years American ginseng sampling sites are located at 7 towns.The samples of soil and plant root were collected in the autumn（September and October）of 2017-2019.The saponin contents of American ginseng and 11 soil chemical properties were measured.The minimum data set（MDS）for assessment of the quality of soil fertility quality was established by correlation analysis and principal component analysis.The evaluation indexes were normalized by membership function.Soil quality index（SQI）that indicates soil comprehensive fertility quality level was calculated according to the critical value of membership function and weight value of each soil index in MDS.The results showed that the total saponin（Rg1+Re+Rb1）content of American ginseng in samples ranged from 1.76%to 7.94%.The yield of 8 plots in 2019 ranged from 3818.7 kg/hm2 to 8996.4 kg/hm2.MDS includes organic matter,alkaline nitrogen,exchangeable calcium,exchangeable magnesium,effective iron,effective copper,and effective zinc.Based on the mean of 4.825%of total saponin,threshold value of SQI for the region was determined to be 0.15,and 86.36%of soil samples in the county were above the threshold value.The methods and parameters are applicable to selection of high quality American ginseng planting sites and guiding rational fertilization.It is also as a reference for the evaluation of soil fertility quality of other medicinal plants.