地表覆盖对渭北旱作苹果园土壤细菌群落结构及多样性的影响

Effect of ground mulch managements on soil bacterial community structure and diversity in the non-irrigated apple orchard in Weibei Loess Plateau

摘要:

摘要:【目的】以渭北旱作苹果园4种覆盖模式为研究对象，探索了不同覆盖措施对土壤细菌群落结构及多样性的影响。【方法】应用变性梯度凝胶电泳(PCR-DGGE)技术结合克隆和测序的方法，分析和比较了不同地表覆盖措施及苹果生育期土壤细菌的群落结构及组成。【结果】不同覆盖模式下土壤细菌群落结构和多样性存在显著差异，细菌优势种群及其数量受覆盖措施和苹果生育期的共同影响:幼果期和膨大期，生草覆盖和秸秆覆盖显著提高了土壤细菌多样性和丰富度，地膜覆盖细菌多样性和丰富度较对照有所提高但未达到显著水平;成熟期对照的细菌多样性达到峰值(2.78)且与其他处理差异显著，这可能是因为土壤中r-策略生存的细菌在该时期得到迅速生长和繁殖的缘故。聚类分析和除趋势对应分析结果显示，细菌群落结构差异与苹果生育期相关，同时受覆盖措施影响，其中生草覆盖与秸秆覆盖土壤样品多聚为一簇，而地膜覆盖与对照相似度较高，说明生草和秸秆覆盖处理土壤细菌群落结构变化比较显著。代表性序列(共22条)测序分析显示，果园土壤细菌的优势菌群为Proteobacteria(10条)和Bacteroidetes(5条)，另外Acidobacteria、Firmicutes、Actinobacteria 等也被检测出。其中有些条带只在特定时期某个处理中表现出优势，如Fusobacterium sp.只在幼果期秸秆覆盖处理出现，有些条带则为各处理共有只是亮度有所不同，如Flavobacterium sp.，然而这些共有或者特异性条带所代表的细菌类群在土壤中的生态功能及其生理生化特征有待进一步明确。【结论】植物地表覆盖(生草/秸秆)能够显著改变土壤细菌群落结构，提高土壤细菌多样性和丰富度，具有土壤优化效应，而地膜覆盖在本研究中与对照无显著差异。

Abstract:

Abstract:［Objective］We studied the changes in soil bacterial communities induced by ground mulch managements at different apple growth periods.［Methods］We adopted the denaturing gradient gel electrophoresis (DGGE) with PCRamplified 16S rRNA fragments to determine soil bacterial community structure and diversity.［Results］ Soil bacterial community structure with different ground mulch managements were significantly different． Both the mulch management strategies and apple growth periods affected the predominant groups and their abundance in soil bacterial communities．Grass mulch and cornstalk mulch treatments had higher bacterial diversity and richness than the control at young fruit period and fruit expanding period，whereas film mulch treatment had no significant difference compared with the control．During mature period，bacterial diversity in the control reached its maximum，which may be ascribed to the rapid growth and reproduction of the r-selection bacteria． The clustering and detrended correspondence analysis revealed that differences in soil bacterial communities were closely correlated to apple growth periods and ground mulch managements．Soil samples from the grass mulch and cornstalk mulch treatments clustered together while those mulched with plastic film treatment were similar to the control．The most abundant phylum in soil bacterial community was Proteobacteria followed by Bacteroidetes． Some other phyla were also detected，such as Acidobacteria，Firmicutes，Actinobacteria and Chloroflexi． ［Conclusion］ Mulching with plant (Grass/Cornstalk) had great effects on soil bacterial community structure and enhanced the diversity while film mulch management had no significant effects．