关键词: 唐古特大黄, 生长年限, 土壤, 理化性质, 微生物群落

Abstract: In order to explore the change rule of soil physical and chemical properties and microbial community composition in different growing years of Rheum tanguticum,the farmlands without planting Rheum tanguticum was used as control (site 1),and the farmlands with growing Rheum tanguticum for 1 to 3 years (site 2,site 3 and site 4)were designed as planting years treatments.The soil physical and chemical properties and microbial community structure of the root of Rheum tanguticum in different growing years were studied by conventional determination method and plate method.The results showed that except for site 1,the content of water,organic matter and total potassium increased gradually with the increase of planting years of Rheum tanguticum,while pH value decreased with the increase of planting years of Rheum tanguticum.The total phosphorus content was the highest in site 4,and the total nitrogen content was the highest in site 3.Comparing the physical and chemical indexes of different soil layers in the same point,it can be seen that the soil water content of the third layer (30—45 cm) of site 1 and site 3 was significantly higher than that of the first layer (0—15 cm) and the second layer (15—30 cm),but there was no significant difference in other sites.The pH value in the second layer of site 1 was significantly higher than that in the third layer,but there was no significant difference with that in the first layer,and there was no significant difference in other sites.The content of organic matter in the second layer of site 2 was the highest,and the content of organic matter in the first layer was significantly higher than that in second and third layers in other sites.The contents of total nitrogen,total phosphorus and total potassium were different in different sites and there was no obvious rule.The number of soil bacteria was the most,followed by actinomycetes and fungi.The number of bacteria and actinomycetes was significantly negatively correlated with the growing years of Rheum tanguticum,and significantly positively correlated with the content of organic matter and total potassium,and the number of fungi was significantly positively correlated with the growing years of Rheum tanguticum and the content of total phosphorus.It showed that long-term cultivation of Rheum tanguticum could inhibit the communities of bacteria and actinomycetes in soil,but promote the growth of fungi.

Key words: Rheum tanguticum, Growth age, Soil, Physical and chemical properties, Microbial community