不同种植年限宁夏枸杞根际微生物的群落多样性

为了解长期人工种植宁夏枸杞根际土壤微生物群落结构特征及其与AM真菌侵染率的关系，本研究分析测定了种植5、10、15 a和24 a宁夏枸杞根际AM真菌的定殖情况和土壤理化性质，并利用PCR-DGGE技术分析了不同种植年限宁夏枸杞根际土壤微生物多样性。结果表明，不同种植年限宁夏枸杞根际土壤pH、速效磷、速效钾、硝态氮存在显著差异，速效磷、速效钾、硝态氮含量在10 a达到最大，这可能与长期施肥及植物对氮磷钾的利用率有关。测序结果表明，随着种植年限的增长，宁夏枸杞根际土壤的微生物多样性呈一定程度的下降趋势，宁夏枸杞根际AM真菌的香农指数在种植5 a时最高，条带数最多，为11条，在种植10 a时显著降低（与种植5 a枸杞相比），在种植24 a时达到最低。根际细菌的香农指数在种植5 a时最高，条带数最多，为31条，说明5 a生宁夏枸杞根际根中细菌种类最多，在种植15 a时显著降低（与种植10 a相比）。通过相关性分析发现，孢子密度差异显著，孢子密度与铵态氮显著正相关，菌根侵染率与铵态氮呈负相关。AM真菌物种丰度与速效钾、硝态氮显著正相关，与土壤pH显著负相关，均匀度指数与pH正相关，与速效磷、铵态氮显著负相关。由此可见，树龄和土壤因子在一定程度上影响根际微生物群落结构。

Diversity of Microbial Community in Rhizosphere Soils of Lycium barbarum Relative to Cultivation History

The objective of this study was to understand the microbial community characteristics of rhizosphere soil and the relation with arbuscular mycorrhizal colonization in long-term cultivation of Lycium barbarum.The AM fungus colonization status and physicochemical properties of the L.barbarum cultivation soil were analyzed.PCR-DGGE technique was applied to analyze the microbial community in the rhizosphere of L.barbarum with different cultivation time (5,10,15,and 24 years) in a nursery of Yinchuan,Ningxia,China.The results showed that soil pH,readily available phosphorus (P),readily available potassium (K),and nitrate nitrogen (N) in rhizosphere soil significantly differed amoung the soils with different cultivation time.The readily available P,readily available K,and nitrate N reached maximum at 10 years,which may due to long-term fertilization and plant utilization of N,P,and K.According to the results of sequence analysis of DGGE dominant bands,the microbial diversity of rhizosphere soil decreased as the increase of cultivation time.The Shannon-Weiner index of AM fungi from the rhizosphere soil was the highest in 5 years and had 11 bands,which significantly reduced in 10 years (compared with in 5 years) and reached the lowest in 24 years.The Shannon-Weiner index of bacteria from the rhizosphere soil was the highest in 5 years and had 31 bands,which significantly reduced in 15 years (compared with in 10 years).According to the correlation analysis,ammonium N was positively correlated with spore density,and negatively correlated with arbuscular mycorrhizal colonization.Spore density was positively correlated with ammonium N.Species richness was positively correlated withthe readily available K and nitrate N,positively correlated with pH.Evenness index was positively correlated with pH,negatively correlated with the readily available P,and ammonium N.Furthermore,plant ages and soil factors affected rhizosphere soil AM fungi community characteristics to some extent.