木质素与蚯蚓对黑麦草生物量及土壤微生物群落的影响

采集农田土壤,设置添加木质素和蚯蚓不同组合处理的黑麦草盆栽试验,在测定植物生物量的基础上,结合定量PCR、高通量测序等方法,研究木质素和蚯蚓及其联合作用对土壤细菌、真菌群落的影响。结果显示:木质素显著降低了黑麦草的生物量,而蚯蚓能够缓解木质素的抑制作用,促进黑麦草生长。木质素明显抑制了土壤细菌、真菌数量,并改变群落结构,以Sphingomonadaceae、Methylophilaceae为标志的降解细菌和担子菌等潜在降解真菌显著富集;单一加入蚯蚓对土壤微生物的影响相对较小,木质素和蚯蚓组合处理显著提高细菌、真菌数量,改变上述降解微生物的丰度。这些结果表明,木质素降低土壤微生物数量,并可能通过其自身降解释放的酚类化感物质抑制植物生长,对土壤生态系统健康产生不利影响;蚯蚓与木质素联合处理影响土壤中木质素降解微生物组成,微生物数量与植物生物量均表现增加趋势,蚯蚓有利于土壤中木质素的微生物代谢,并为植物生长提供更多的养分。本研究为农田生态系统木质素资源化利用提供了科学依据。

Effects of Lignin and Earthworm on Ryegrass Biomass and Soil Microbial Community

The decomposition of lignin is mainly driven by microorganisms, and the released phenols may have an inhibitory effect on plants. Earthworms are considered as soil ecosystem engineers, and they have multiple effects on soil ecological processes and microbial communities. In order to investigate the effects of lignin and earthworms and their combined effects on plant biomass and soil microorganisms, farmland soils were collected, and ryegrass pot experiments with different combinations of lignin and earthworms were set. Based on the determination of biomass, combined with methods such as quantitative PCR and high-throughput sequencing, the effects of lignin and earthworms on soil bacterial and fungal communities were studied. The results showed that lignin significantly reduced the biomass of ryegrass, while earthworms could alleviate the inhibitory effect of lignin and promote the biomass of ryegrass. Microbial analysis showed that lignin significantly inhibited the number of soil bacteria and fungi, and changed the community structure. Potential degrading bacteria such as Sphingomonadaceae and Methylophilaceae were significantly enriched. The effect of adding earthworms on soil microorganisms was relatively small. The combined treatment of lignin and earthworms significantly increased the copy number of bacteria and fungi and changed the abundance of the aforementioned degrading microorganisms. These results indicate that lignin reduces the copy number of soil microorganisms, and may inhibit plant growth through phenolic allelopathic substances released by its own degradation, which adversely affects the health of soil ecosystems. The combined treatment of earthworm and lignin affected the composition of lignin-degrading microorganisms in the soil, and both the number of microorganisms and plant biomass tended to increase, suggesting that earthworm is beneficial to the microbial metabolism of lignin and lignin-derived phenolic compounds in the soil. This study provides a scientific basis for the utilization of lignin resources in farmland ecosystems.