Evolution characteristics of bacteria in soil of medical plant (Lycium barbarum L.)

ObjectivesStudying effects of soil layer, seasons and stand ages on soil bacteria of Lycium barbarum L. is very important to reveal trends of soil quality change in cultivated regions of L. barbarum.

MethodsThe study was achieved by high throughput sequencing analysis of bacteria community structure and abundance of soil samples from L. barbarum fields in Zhongning County, Ningxia Province, which is the origin of L. barbarum. Three stand ages of L. barbarum were selected, small-age (< 1 year), middle-age (6 year) and old-age (12 year). The soil samples (three plots each) were collected in spring, summer and autumn in surface (0–20 cm) and subsurface (20–40 cm) layers.

ResultsCompared to the small-age of soil, the total organic carbon (TOC) of 0–20 cm in spring and summer and total organic nitrogen (TON) of 0–40 cm of the middle-age and old-age were increased and then decreased and the microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) of 0–20 cm in spring were increased from the small-age to old-age, while those of 20–40 cm in spring and autumn were decreased. The MBC of 0–20 cm of the middle-age in summer was highest, while the MBN was lowest. With the increase of stand age, the soil bacteria community diversity of L. barbarum was increased and then decreased. Proteobacteria, Actinobacteria and Bacteroidete were prodominent plyumn. The relative abundance of Proteobacteria of the old-age was higher than that of the small-age and middle-age, Planctomycetes and Chloroflexi of small-age were higher than the middle-age and old-age. Xanthomonadales, Rhodobacterales and Rhizobiales were the prodominent classes, especial for the middle-age in autumn and old-age in three seasons. There were different effects of soil layer, seasons and stand ages on the microbial biomass.

ConclusionsWith the increase of stand age, microbial biomass and diversities of soil of L. barbarum have an increased–decreased tendency. Compared to the small-age and middle-age, the soil of the old-age had maximum Xanthomonadales. Carbon of soil was influenced significantly by soil layers in our study, nitrogen and bacterial community diversities were influenced significantly by stand ages and carbon, MBC and MBN were all influenced significantly by seasons.