不同施氮量对北柴胡质量及其土壤微生态影响

Effects of Different Nitrogen Application Rates on Quality and Soil Microecology of Bupleurum chinense

目的:探究不同施氮量与柴胡产量、质量及土壤微生物群落变化之间的关系,为合理施肥提供科学依据。方法:以二年生北柴胡为试验对象,研究不施氮肥(0 g/盆)、低氮(1.377 g/盆)、高氮(2.754 g/盆)三个处理的北柴胡产量、质量及其土壤化学性质、酶活性、微生物功能多样性的差异。结果:外源施氮主要促进根中柴胡皂苷a的积累,其中低氮组含量较对照组提高51.35%,且该处理可显著提高根重及根冠比。同时氮肥的施入引起土壤pH值降低、β-葡萄糖苷酶活性增强,并促进土壤微生物代谢。冗余分析结果表明,电导率、pH值是影响土壤微生物碳源代谢的主要因素,以醇类、胺类为碳源的微生物对氮素较为敏感。结论:适量的氮有利于柴胡根系生长发育及土壤微生态平衡,若土壤含氮量超过阈值,则会对植物根系发育、次生代谢产物及微生物产生一定的不利影响。

Objective:To explore the relationship between different nitrogen application rates and Bupleurum chinense yield,quality,soil microbial community changes,so as to provide scientific basis for rational fertilization.Methods:The yield,quality,soil chemical properties,enzyme activities and microbial functional diversity of biennial Bupleurum chinense were studied under three treatments,including no nitrogen fertilizer(0 g/pot),low nitrogen(1.377 g/pot),high nitrogen(2.754 g/pot).Results:Exogenous nitrogen application mainly promoted the accumulation of saikosaponin in roots,and the content of saikosaponin in the low nitrogen group was increased by 51.35%compared with the control group.The root weight and root-shoot ratio were significantly increased by the treatment.At the same time,the application of nitrogen fertilizer reduced soil pH value,enhancedβ-glucosidase activity,promoted soil microbial metabolism.The results of redundancy analysis showed that the electrical conductivity and pH value were the main factors affecting the carbon source metabolism of soil microorganisms,the microorganisms with alcohol and amine as carbon sources were more sensitive to nitrogen.Conclusion:The appropriate amount of nitrogen is more beneficial to the root growth and development of Bupleurum chinense and the balance of soil microecology.If the soil nitrogen content exceeds the threshold,it will have certain negative effects on root development,secondary metabolites and microorganisms.