薇甘菊化感物质对土壤氮素矿化的影响及其化感利己作用

【目的】研究入侵植物薇甘菊提取物对土壤氮素矿化的影响及化感利己作用,为薇甘菊通过释放化感物质促进自身生长并排斥本地植物生长提供实验证据,为揭示薇甘菊的入侵机制提供理论依据。【方法】采用经典的化感生测实验、化感物质添加实验以及盆栽控制实验,对比研究薇甘菊及其本地伴生植物水提液和粗提物的化感生测效应、水提液和粗提物添加对土壤氮素的影响以及水提液添加对薇甘菊生长的影响。【结果】与本地伴生种相比,薇甘菊水提液的化感抑制作用较强且促进了土壤硝态氮的生成;而薇甘菊粗提物的化感作用较弱且抑制了土壤铵态氮和硝态氮的生成。水提液盆栽控制实验结果表明,与本地伴生种火炭母相比,薇甘菊水提液具有显著的化感利己作用,这与薇甘菊水提液处理后薇甘菊生长土壤中的蛋白酶活性增强和有效氮含量增加相一致。【结论】薇甘菊可通过水溶性化感物质促进有效氮的生成来实现化感利己作用。

Effects of allelochemicals of Mikania micrantha H.B.K. on soil nitrogen mineralization and its self-interested allelopathy

Aim] This study investigated how allelochemicals extracted from the invasive plant Mikania micrantha affected soil nitrogen mineralization and how self-interested allelopathy may occur. Our aim is to provide new experimental evidence for the promotion of M. micrantha growth and its ability to repel native plants by releasing allelochemicals, thus providing insights into the invasive mechanism of M. micrantha.Method] We conducted a classical bioassay for allelopathic experiments, the exogenous addition of allelochemicals to soil and an outdooor pot experiment to compare the differences between the allelochemical effects of aqueous extracts and crude extracts of M. micrantha and its two native companion plants (Persicaria chinensis and P. scandens). The effects of water extract and crude extract addition on soil nitrogen mineralization were investigated by determining ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃^--N) concentrations, as well as the effects of aqueous extract addition on the growth of M. micrantha.Result] The results showed that the M. micrantha aqueous extracts (0.025 g·mL^-1 DW) exhibited a strong allelopathic inhibition effect compared to the extract of its two native companion species (P. chinensis and P. scandens), and soil nitrate nitrogen (NO₃^--N) increased substantially after the addition of M. micrantha aqueous extract. By contrast, the allelopathic effect of M. micrantha crude extracts was weak and soil available nitrogen (NH₄⁺-N and NO₃^--N) decreased significantly after the addition of crude extracts of M. micrantha. In this context, aqueous extracts were further used to investigate the growth of M. micrantha through an ourtdoor pot experiment, and the results showed that, compared to that of the native species P. chinensis, the aqueous extracts of M. micrantha displayed significant and self-interested allelopathy. This may be related to the increased protease activity and available nitrogen in M. micrantha rhizosphere soil in the outdoor pot experiment with the aqueous extracts of M. micrantha.Conclusion] M. micrantha can promote the production of available nitrogen through water-soluble allelochemicals to realize self-interested allelopathy.