引黄灌区不同种植年限紫花苜蓿土壤养分与细菌群落特征研究

以宁夏引黄灌区种植年限为1～6年(2012-2017年)的紫花苜蓿地土壤为研究对象,采用16S rRNA扩增子测序技术对细菌群落组成、丰度和多样性等特征进行研究,分析了土壤养分与细菌种群多样性的相关关系。结果表明:不同种植年限苜蓿地土壤中共检测出细菌约40个门、78个纲、151个目、275个科和416个属;在门水平下细菌的优势门类为变形菌门、酸杆菌门和拟杆菌门,共占细菌总数的68%;随种植年限的增加,细菌菌群丰度和多样性变化表现为1 yr>5 yr>3 yr>4 yr>2 yr>6 yr;土壤pH、有机碳、全氮和碱解氮呈先降低后增大的变化趋势,且都在第5年时达到最大,与细菌群落组成变化规律基本保持一致。Spearman相关性分析结果表明,有机碳、全氮和碱解氮对细菌群落组成具有显著影响(P<0.05)。

Correlation between soil nutrient status and the bacterial community composition in alfalfa stands of different ages in the Yellow River irrigation area

The soil bacterial community composition, abundance and diversity were studied in alfalfa stands between 1-6 years of age (i.e. established 2012-2017), in the Ningxia Yellow River irrigation area. The determination of the soil bacterial community characteristics was achieved by DNA extraction followed by PCR amplification, and sequencing using the HiSeq platform. The 16S rRNA amplifier sequencing technique was used in the study. The correlation between soil nutrients and bacterial population diversity was analyzed. The results indicate that there are about 40 phyla, 78 classes, 151 orders, 275 families and 416 genera of bacteria in the soils of the various alfalfa stands of different ages. At the phylum level, the dominant genera of bacteria detected were Proteobacteria, Acidobacteria and Bacteroidetes, accounting for 68% of the total bacterial population. The ranking of bacterial abundance and diversity with stand age was: 1 yr>5 yr>3 yr>4 yr>2 yr>6 yr. Soil pH, organic carbon, total nitrogen and alkali-hydrolysable nitrogen all decreased initially, and then increased with stand age, reaching their maxima at year 5. The result is basically consistent with findings of other studies of factors affecting bacterial community composition. Analysis using Spearman's correlation showed that organic carbon, total nitrogen and alkaline nitrogen were significantly (P<0.05) correlated with bacterial community composition. In general, the dominant taxa of soil bacterial communities present in the Yellow River irrigation area did not change with stand age, but population numbers and bacterial community diversity did vary from year to year, though not with any consistent trend over time. Soil organic carbon, soil alkali-hydrolysable nitrogen and soil total nitrogen were the main factors associated with changes in bacterial taxa present across years.