药用植物宁夏枸杞 (Lycium barbarum L.) 土壤细菌群落演替特征

【目的】研究土层、季节和树龄对宁夏枸杞土壤细菌群落结构的影响，对揭示枸杞种植区域土壤质量变化规律具有重要意义。【方法】以宁夏枸杞之乡—宁夏回族自治区中宁县为研究区，采用高通量测序分析了不同土层、季节和树龄条件下枸杞土壤细菌生物量及细菌群落结构和丰度的变化趋势。【结果】随着枸杞树龄增加，与幼龄 (种植当年，< 1 年) 枸杞土壤相比，春季和夏季 0—20 cm 中龄 (6 年) 和老龄 (12 年) 土壤总有机碳 (total organic carbon，TOC) 及 0—40 cm 土壤总有机氮 (total organic nitrogen，TON) 含量先增加后减少；春季不同树龄 0—20 cm 土壤微生物生物量碳 (microbial biomass carbon，MBC)和微生物生物量氮(microbial biomass nitrogen，MBN)一直增加，但春季和秋季 20—40 cm 则呈相反趋势。夏季中龄植株表层土壤 MBC 最高，但 MBN 却最低。随着树龄增加，枸杞表层土壤细菌多样性普遍呈先增加后减小的趋势。枸杞土壤变形菌门 Proteobacteria、放线菌门 Actinobacteria、拟杆菌门 Bacteroidete 在细菌群落中占绝对优势。相同季节老龄土壤 Proteobacteria 相对丰度普遍高于幼龄和中龄，幼龄土壤 Planctomycetes 和绿弯菌门 Chloroflexi 丰度高于中龄和老龄。变形杆菌中黄色单胞菌 Xanthomonadales、红杆菌 Rhodobacterales 和根瘤菌 Rhizobiales 占主导地位，尤其是在秋季中龄和 3 个季节的老龄枸杞土壤。土层、季节和树龄对土壤微生物数量影响不同。【结论】随着树龄增加，宁夏枸杞表层土壤微生物生物量和细菌多样性呈先增加后降低的趋势。老龄植株土壤 Xanthomonadales 数量相对最多。土层对枸杞土壤碳分布有极显著影响，树龄主要显著影响土壤氮源和细菌群落多样性，季节对枸杞土壤碳源、微生物量碳氮均有极显著影响。

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

Objectives] Studying 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.Methods] The 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 ofL.barbarum.Three stand ages ofL.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.Results] Compared 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.Conclusions] With 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.