Objective  The aim is to explore the effects that soil nutrient availability, enzyme activity, and bacterial community structure exerted on the growth stage of citrus, try to provide a constructive ground for the scientific management of citrus growing.

  Method  Under the same conditions of management measures and trees without diseases, four kinds of growing conditions were collected ( level Ⅰ represents the best condition; level Ⅱ represents good condition; level Ⅲ represents bad condition; level Ⅳ represents growing low and no production) to measure the soil nutrient availability, enzyme activity and bacterial microbial community in the root zone of citrus trees.

  Result  The contents of total nitrogen and available potassium in grade Ⅳ soil were significantly lower than those in other grade types (P < 0.05). The contents of available calcium, magnesium and boron in grade Ⅰ were higher than thosein the other grades (P < 0.05). Copper content in root zone soil of grade Ⅳ was significantly lower than that in other grades (P < 0.05). The β-glucosidase and cellobiose hydrolase in grade Ⅰ were significantly lower than those of other grades. The abundance of chloroflexi in grade I was significantly higher than in grade Ⅳ on phylum, and pseudomonas in grade Ⅰ was significantly higher than in the other grades on the genus (P < 0.05). The soil bacterial community in the grade Ⅳ citrus root area was separated from grade Ⅰ-Ⅲ citrus trees. The redundant analysis found that available potassium and calcium were the related factors affecting soil bacterial community structure in the root zone of different grades of citrus.

  Conclusion  Different growing citrus soils in effective potassium, total nitrogen, effective calcium, magnesium, boron, and other nutrient content have significant differences, resulting in citrus growth difference, then the lack of trace elements also reminds farmers in the orchard daily fertilization. In addition, the application of many elements should also pay attention to the trace elements of fertilizer application. The microbial community influenced the citrus growth. The soil microbial communities varied greatly among the citrus root areas, and the dominant bacteria - Bacillus and Pseudomonas are speculated that soil microbial communities influence soil nutrients and thus affect the growth and development of citrus.