不同大豆连作年限对黑土细菌群落结构的影响

大豆连作导致作物产量下降、病原微生物富集和土壤退化等问题日趋严重。然而,目前关于大豆连作对土壤细菌群落结构组成及多样性分布的影响及发生机制尚不清楚。采用高通量测序技术,对大豆连作(不同年限)和大豆-玉米轮作下的黑土细菌16S rRNA基因进行测序分析。结果表明:轮作5年(CR5)和13年长期连作(CC13)处理显著增加了土壤pH、全氮(TN)、全磷(TP)和速效养分(AN、AP和AK)含量。与短期连作相比,CR5和CC13处理均提高了细菌群落的OTUs数量、PD值、Chao1指数和Shannon指数。聚类分析图谱结果显示细菌群落结构组成受到轮作和连作年限的双重影响,而土壤pH、TN、TP、AN、AP和AK是细菌群落结构发生变化的主要驱动因子(P0.05)。此外,VPA分析发现上述土壤因子中,土壤pH对细菌群落结构变化的贡献度最大。本研究证明大豆长期连作提高了土壤养分含量和细菌群落的丰富度和多样性指数,从分子生物学的角度证实大豆长期连作在一定程度上改善了土壤环境,为大豆连作障碍的研究提供了理论依据。

Effects of continuous cropping years of soybean on the bacterial community structure in black soil

SoybeanGlycine max (L.) Merill.] continuous cropping may lead to yield decline, enriched pathogenic microbes, and soil degradation. Although the problems can become serious, the mechanisms of how the bacterial community is affected and possible links between these effects and cropping systems remain unclear. Therefore, we comparatively investigated the bacterial diversity and structure of the soil samples collected from soybean continuous cropping with different years (CC-) and cropping rotation with maize (CR) using Illumina Miseq sequencing methods. The results showed that soil pH, total N, total P, and available nutrient content were significantly higher in CR5 and CC13 treatments. Compared with short-term continuous cropping, CR5 and CC13 treatments increased the number of OTUs (operational taxonomic units), value of PD (phylogenetic diversity), Chao1 index, and Shannon index of bacterial communities. The cluster analysis revealed that the bacterial community compositions were affected both by the cropping system and cropping years, and soil pH, TN (total N), TP (total P), AN (available N), AP (available P), and AK (available K) were the main factors in driving bacterial community structure (P < 0.05). In addition, a variance partitioning analysis (VPA) revealed that the effect of soil pH was a primary factor in determining bacterial community composition. In this study, the results showed that soil nutrient content and richness and diversity index of the bacterial community increased under CC13 treatments, which indicated that long-term soybean continuous cropping improved the soil environment to some extent. This study provides scientific data for studying the ecology of soybean continuous cropping.