| Objective:This study aimed to explore the effects of two kinds of photosynthetic bacteria(Rhodopseudomonas palustris and mixed photosynthetic bacteria)on cultivated Codonopsis pilosula at different concentrations,to explore the law between the internal and external quality of Codonopsis pilosula under the application of photosynthetic bacteria and its influence on the rhizosphere soil environmental quality of Codonopsis pilosula and to determine the optimal concentration of photosynthetic bacteria in the cultivation of Codonopsis pilosula.Through the correlation analysis of soil environment and Codonopsis pilosula quality,to comprehend the interaction of microbe-soil-plant.Methods:Part 1: The experimental base of Zhendong Daodi Medicinal Materials Development Co.,LTD.,Pingshun County,Shanxi Province,was selected as the experimental area,and the Codonopsis pilosula cultivated for one year was taken as the cultivated seedlings.Nine kinds of photosynthetic bacteria diluted with different concentrations(Rhodopseudomonas palustris and mixed photosynthetic bacteria)were used to spray Codonopsis pilosula three times during one-year growth period.After maturation and excavation,the growth characteristics(appearance morphology,dry weight per root,fresh weight per root,average root length and average root diameter)of Codonopsis pilosula were measured to evaluate the effect of photosynthetic bacteria on appearance characteristics of Codonopsis pilosula.Part 2: The content of trace elements iron,manganese and zinc were determined by atomic absorption spectrophotometry,and the content of selenium was determined by atomic fluorescence spectrophotometry.The total nitrogen content was determined by Kjeldahl method,the total phosphorus content was determined by molybdenum-antimony colorimetric method,and the total potassium content was determined by flame photometry.Syringin,lobetyolin and atractylodes Ⅲ in Codonopsis pilosula were extracted by ultrasound,and their contents were determined by HPLC.The polysaccharide of Codonopsis pilosula was extracted by water extraction and alcohol precipitation,and its content was determined by UV-VIS spectrophotometry.Pesticide residues were determined by Gas chromatography and heavy metals were determined by atomic absorption spectrophotometer and atomic fluorescence spectrometry.The correlation between appearance quality and nutritional quality of Codonopsis pilosula was analyzed,and the effect of microbial agents on the quality of Codonopsis pilosula was evaluated from the aspect of nutritional quality,and the correlation between appearance quality and nutritional quality was explored.Part 3: According to the methods in Soil Agrochemical Analysis compiled by Bao Shidan(2015),we measured and analyzed the data of the nature of the rhizosphere soil(water content,p H,conductivity),soil fertility(organic matter,available phosphorus,alkali hydrolyzable nitrogen,available potassium),soil enzyme activity(urease,sucrase,alkaline phosphatase),and the number of soil microorganisms(bacteria,fungi,actinomycetes)of Codonopsis pilosula,and explored the impact of photosynthetic bacteria agents on the soil environment,and analyze the correlation between microorganisms,soil,and plants.Part 4 : The experiment of Codonopsis pilosula was carried out under specific conditions in laboratory.The plant height,leaf number,main stem branch number and main stem diameter were measured on the 30 th,60th and 90 th day after treatment.After harvest,the fresh and dry weight of the above-ground and underground parts of Codonopsis pilosula,as well as the content of the effective components lobetyolin,atractylodes Ⅲ and Codonopsis pilosula polysaccharide was determined,to verify whether the results of field experiment are consistent or similar.Results:Part 1: Photosynthetic bacterial agents can increase the main roots and fibrous roots of Codonopsis pilosula,with an increase of up to 10% to 40%.The relatively reasonable plan for photosynthetic bacterial agents to improve the appearance quality of Codonopsis pilosula is 100-fold dilution of Rhodopseudomonas palustris or 50-fold dilution of mixed photosynthetic bacteria.Part 2: Photosynthetic bacteria bacteria can promote the enrichment of trace elements iron,manganese and zinc,increase the total phosphorus content of Codonopsis root,increase the contents of lobetyolin and Codonopsis pilosula polysaccharide,and significantly reduce the contents of heavy metals lead,mercury and copper,especially the effect on lead and mercury,the highest can reduce 52.73% lead and 55.88% mercury.The heavy metal content and pesticide residues of Codonopsis pilosula in all experimental groups were in line with national industry standards.The correlation analysis between appearance quality and nutritional quality of Codonopsis pilosula showed that trace elements were the main factors affecting nutritional quality.It was determined that the relatively reasonable use of photosynthetic bacteria bactericide to improve the nutritional quality of Codonopsis pilosula was 100 times dilution bactericide of Rhodopseudomonas palustris.Part 3: Photosynthetic bacterial agents can increase soil water content and soil conductivity,increase the content of available phosphorus in soil,and reduce the number of bacteria in soil.Mixed photosynthetic bacterial agents significantly increased soil urease and alkaline phosphatase activities,while Rhodopseudomonas palustris agents were the opposite.Based on multi-factor correlation analysis,soil water content,soil available phosphorus content,soil enzyme activity and soil bacteria were the main factors affecting the quality of Codonopsis pilosula.Part 4: Photosynthetic bacteria bacteria could increase plant height,leaf number,branch number of main stem and fresh/dry weight of aboveground and underground parts of Codonopsis pilosula in potted plants,and the effect of mixed photosynthetic bacteria bacteria was better.The 100-fold dilution of Rhodopseudomonas palustris can significantly increase the content of lobetyolin by 4-9 times and the content of polysaccharide by 1-2times in underground parts.The laboratory results are in agreement with the field results.Conclusion:Photosynthetic bacteria agents improved the appearance quality and nutritional quality of Codonopsis pilosula in different degrees,and the beneficial elements had a great effect on the appearance quality of Codonopsis pilosula.The quality of Codonopsis pilosula was determined comprehensively.The suitable concentration of photosynthetic bacteria bactericide could improve the quality of Codonopsis pilosula and increase farmers’ income.At the same time,photosynthetic bacteria agents can also maintain the balance of soil environment and change the composition of soil microorganisms,and soil environment is the main factor affecting the quality of Codonopsis pilosula.In this paper,the effects of photosynthetic bacteria on the quality of cultivated Codonopsis pilosula were preliminarily explored through field experiments,and the corresponding verification was also carried out in the laboratory.It was determined that the best scheme of photosynthetic bacteria was100 times diluted by Rhodopseudomonas palustris.This conclusion provided a theoretical basis for guiding the application of photosynthetic bacteria in Codonopsis pilosula planting.To provide reference for exploring the influence mechanism of photosynthetic bacteria on Codonopsis pilosula. |
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