| Objective: Dendrobium officinale has highly medicinal and sanitarian value and has huge market demands.Most of kinds of Dendrobium officinale in the market come from artificial cultivation.But,unified technical standard in its planting management has not been used,most of the planting bases have no GAP certification,and using pesticides and chemical fertilizers is usual,harmful elements exist mostly,the quality and safety of Dendrobium officinale cannot be guaranteed.The purpose of this study is to find a scientific safe and healthy method in the planting of Dendrobium officinale,and to provide a reference for the standardized planting of Dendrobium officinale,and to realize the sustainable development and utilization of Dendrobium officinale.Methods: At present,there are many planting bases and various techniques in planting management of Dendrobium officinale,and planting technology is kept unopen.In order to obtain complete information and data in planting management,this study selected four Dendrobium officinale planting bases that seedlings are selected from the same source and can obtain complete planting management information,and products of the bases are sold in the market every year,the planting management technology of each base has been investigated for two consecutive years,and the fresh stalks of Dendrobium officinale were collected from the four bases at the same time,and 3 samples of fresh stalks were randomly collected at each base.The research is carried out on yield,water,ash,polysaccharide content,compositions of polysaccharide and exogenous harmful substances(pesticides,heavy metals)of Dendrobium officinale in order to evaluate the quality of the Dendrobium officinale comprehensively and scientifically,and this method is used to evaluate its planting technology.The content of polysaccharides was determined by phenol-sulfuric acid method,and the pre-column derivatization-HPLC method was used to evaluate the polysaccharide composition.The pesticide residue was evaluated by GC-MS and HPLC.The heavy metals were evaluated by ICP-MS.Results:(1)Planting methods: Arched steel tube sheds and elevated seedbeds are used to cultivate Dendrobium officinale,and all the cultivation substrates are pine bark and moss,and the planting origin and transplanting methods of Dendrobium officinale are the same at 4 bases,the differences among the bases are shade nets,water management and pesticides and fertilizers.(2)The total water content of Dendrobium officinale collected was less than 12%,and the ash content was less than 6%.(3)Productivity comparison: The production of Yunnan Base2 is significantly less than Kunyang,Hongguo and Yunnan Base1;Kunyang,Hongguo and Yunnan Base1 have no significant differences each other.(4)Comparison of polysaccharide content: The polysaccharide content of Dendrobium officinale at Yunnan Base1 and Yunnan Base2 was much higher than Base Kunyang and Base Hongguo.Comparing the content of polysaccharides of Dendrobium officinale collected at 4 different bases in 2016 and 2017 respectively,the polysaccharide content of Dendrobium officinale for two years' planting was significantly higher than one year's planting,the polysaccharide content of Dendrobium officinale at Yunnan Base2 for two years' planting was much higher than one year planting,but there was no significantly difference.(5)Study on the constituents of polysaccharides: Polysaccharide of Dendrobium officinale consists of D-mannose,D-glucose,rhamnose,galactose,Dxylose and D-arabinose.The monosaccharide content comparison at 4 different bases: D-mannose> glucose> galactose,rhamnose,D-xylose and D-arabinose;D-mannose is the main component of polysaccharide,the second is glucose and galactose,rhamnose,D-xylose and D-arabinose in Dendrobium officinale collected were rarely,less than 1%,and the content of D-mannose at each base in 2016 and 2017 is 13% to 38%.Comparing the mannose and glucose contents of Dendrobium officinale at 4 different bases: For two consecutive years,the content of mannose of Dendrobium officinale at Yunnan Base1 was much higher than other bases,the content of glucose of Dendrobium officinale at Yunnan Base1 and Base Hongguo was higher than the other 2 bases.Comparing the monosaccharide content of Dendrobium officinale at the same base in 2016 and 2017: there were no significant differences in content of glucose,mannose,sugar,galactose,xylose,and Arabic sugar in Dendrobium officinale in 2016 and 2017.(6)Pesticide Residues: BHC,DDT,PCNB,carbendazim and metaldehyde were not detected in Dendrobium officinale collected in 2016 and 2017.(7)Heavy Metal Residues: For two consecutive years,the contents of Pb,Cu,Cd,Hg and As in Dendrobium officinale collected from Yunnan Base1 and Yunnan Base2 were less than contents limited in Pharmacopoeia of the People's Republic of China(2015 edition).The contents of Pb,Cu,Hg in Dendrobium officinale from Base Kunyang and Base Hongguo were less than contents limited in the Pharmacopoeia,but the Cd content was significantly higher than the Pharmacopoeia standard.Conclusion: Impurities(moisture,ash)and Pb,Cu,Cd,Hg of Dendrobium officinale produced at Yunnan Base1 and Yunnan Base2 are lower than the standards of Pharmacopoeia of the People's Republic of China.BHC,DDT,PCNB,carbendazim and tetrapolyethylene are not detected,and the polysaccharide content of the mainly active ingredient is much higher than pharmacopoeia standards,which states Dendrobium officinale produced at Yunnan has good quality,but,the management of the Yunnan Base2 is extensive and the output is significantly lower than the other 3 bases.Residues of Cd in Dendrobium officinale produced at two bases,Kunyang and Hongguo are excessive(above 0.3 mg/kg),and which shows the quality from the 2 bases is poor.Based on the comprehensive quality and comparative study of production,the planting management technology adopted at Yunnan Base 1 can not only produce high quality products,but also ensure high yields,which is a scientific,safe and healthy planting management technology that can standardize the Dendrobium officinale planting technology. |
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