Effect Of Compound Functional Bacteria Combined With Amino Acid Fertilizer On The Growth And Early Bolting Of Angelica Sinensis Seedlings

Angelica sinensis is the dried root of Angelica sinensis(Oliv.)Diels,a perennial herb in the Umbelliferae family,and is one of the commonly used traditional Chinese medicines.The cultivation of Angelica sinensis is mainly based on seedling cultivation and transplanting,and its traditional seedling cultivation method is covered with grass,which has the functions of maintaining soil moisture,regulating soil temperature,resisting direct sunlight,inhibiting weed growth,and improving seedling emergence rate.Fresh wheat straw is often used in the cultivation of Angelica sinensis seedlings by covering with grass,with a high carbon to nitrogen ratio(C/N).If the coverage is too thick or an appropriate amount of nitrogen is not supplemented in a timely manner during the seedling cultivation process,it will lead to slow soil microbial decomposition and excessive consumption of soil nitrogen,leading to an increase in the soil carbon to nitrogen ratio,which is not conducive to obtaining sufficient nitrogen nutrition for the seedlings,resulting in slow seedling development and short and yellow plants.Studies have shown that plant rhizosphere growth promoting bacteria,as beneficial microorganisms that colonize the plant rhizosphere,can promote plant growth and the absorption and utilization of soil nutrients through various ways.Amino acid micro-fertilizer provides plants with small molecular amino acids that are easy to absorb and use as nitrogen sources,and can improve the activity and effect of beneficial bacteria.In this study,two functional plant rhizosphere growth-promoting strains with growth-promoting effects were selected and applied in combination with amino acid micro-fertilizer.In the field experiment,the effects of single or mixed application of compound functional bacteria and amino acid micro-fertilizer on the growth of Angelica sinensis seedlings,photosynthetic physiological characteristics,carbon and nitrogen metabolism characteristics,soil nutrients,enzyme activity,seedling quality,and the early bolting and drug status of Angelica sinensis after seedling transplantation were studied.The main research results are as follows:1.Single application of compound functional bacteria,single application of amino acid micronutrient fertilizer,and mixed application of compound functional bacteria and amino acid micronutrient fertilizer can promote the growth of Angelica sinensis seedlings,increase the plant height,root length,root diameter,and biomass accumulation at different stages of the seedlings.Increase the photosynthetic rate and photosynthetic pigment content of seedlings,adjust the chlorophyll fluorescence parameters of seedlings,and improve the photosynthetic performance of seedlings.Regulate the activity of carbon-nitrogen metabolism enzymes in seedlings,enhance the ability of carbon-nitrogen metabolism of seedlings,and promote the accumulation and transformation of carbon-nitrogen metabolites.The compound functional bacteria mainly affected the AI,GOGAT activity and Ls,ΦPSII and ETR increased the contents of glucose,ammonium nitrogen,total amino acid and carotenoid in seedlings.Amino acid micro-fertilizer mainly affects Pn,Ci and Tr of Angelica sinensis seedlings,and increases the content of sucrose and soluble protein in seedlings.The comprehensive performance of mixed application of functional bacteria and amino acid micro-fertilizer was more balanced than that of single application.2.The yield of Angelica sinensis seedlings increased by 18.28%,31.06% and 21.54%respectively after single application of compound functional bacteria,single application of amino acid micro-fertilizer and mixed application of compound functional bacteria and amino acid micro-fertilizer,and the proportion of Angelica sinensis first-grade seedlings increased significantly(P<0.05),and the proportion of first-grade seedlings after the application of compound functional bacteria and amino acid micro-fertilizer reached 64.27%,and the proportion of abandoned seedlings was only 8.79%.The combination of compound functional bacteria and amino acid micro-fertilizer increased the root length,root diameter and single root weight of Angelica sinensis seedlings,increased the content of soluble sugar and soluble protein in roots,and decreased the carbon and nitrogen ratio of seedlings;Improve the activities of soil S-CAT,S-UE,S-SC and S-ALP/AKP enzymes,increase the content of soil total nitrogen,nitrate nitrogen,available phosphorus,available potassium and soil water content,and reduce the content of soil total carbon,ammonium nitrogen and soil carbon to nitrogen ratio.Amino acid micro-fertilizer has a strong effect on the improvement of soil total nitrogen content.The compound functional bacteria can effectively promote the decomposition of soil organic carbon,reduce the total carbon content of soil,and significantly reduce the ammonium nitrogen content of soil.Combined application of compound functional bacteria and amino acid micro-fertilizer is the best,which can effectively increase the yield of Angelica sinensis seedlings,promote the nutrient exchange between soil and roots,and improve the quality of seedlings.3.The seedlings grown well by single application of compound functional bacteria alone,single application of amino acid micro fertilizer and mixed application of compound functional bacteria and amino acid micro fertilizer,with high survival rate and drug rate,low bolting rate and incidence rate.The survival rate of seedlings transplanted by mixed application of compound functional bacteria and amino acid micro fertilizer reached 86.40%,and bolting rate was only 0.37%;The plant height,plant width,stem diameter,main root length,adventitious root number and single root weight of Angelica sinensis were significantly increased after transplanting the seedlings cultivated with compound functional bacteria and amino acid micro-fertilizer;The water content,total ash,acid-insoluble ash,extract and ferulic acid content of Angelica sinensis meet the requirements of the pharmacopoeia.In a word,the best combination of compound functional bacteria and amino acid micro-fertilizer can effectively solve the problem that the imbalance of carbon and nitrogen ratio caused by straw mulching affects the growth of seedlings in Angelica sinensis seedling cultivation,and the seedling cultivation also meets the requirements of Angelica sinensis production.Conclusion: The combined application of compound functional bacteria and amino acid microelement fertilizer can effectively improve the photosynthetic performance and carbon and nitrogen metabolism of Angelica sinensis seedlings,increase the enzyme activities such as S-CAT,S-UE,S-SC and the content of available nutrients in the soil,reduce the soil carbon nitrogen ratio,thereby promoting the growth of Angelica sinensis seedlings,improving the dwarfing and yellowing of seedlings,improving the quality and yield of seedlings,and increasing the survival rate and drug yield of cultivated seedlings after transplanting,reducing the early bolting rate and incidence rate of Angelica sinensis.