The exacerbation of plant invasion by microplastics attracted widespread attention. Pulse resource hypothesis is popular theory to elucidate plant invasion. Our previous work demonstrated biodegradable microplastics (BMPs) could increase the arbuscular mycorrhizal fungi (AMF) colonization rate. Reportedly, AMF can enhance rhizobia colonization. Therefore, we infer the coexistence of BMPs with legumes may lead to an increased colonization of rhizobia with negative feedback regulation of N fixation. This could result in NO3−-N pulse supply, thereby exacerbating plant invasion. Subsequently, a 60-day pot experiment was conducted using Trifolium repens L. as invasive plant and Oxalis corniculata L. as native plant, with 1% or 5% wt BMPs. AMF colonization, BMPs degradation, NO3−-N content and pulse supply, rhizobia colonization, relative competitive intensity, replacement diagrams and NO3−-N utilization were determined. The mechanism was clarified through heat map and structural equation model. The results reveal the greater the NO3−-N consumption by BMPs, the more AMF promoted rhizobia colonization in T. repens, thereby the larger the pulse amplitude of NO3−-N supply, then, the higher the NO3−-N utilization rate of T. repens. It exacerbates T. repens invasion. This study clarifies effects of BMPs on rhizobia's N fixation, and enriches the evidence on mechanism of BMPs exacerbating plant invasion.

中文翻译：

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由可生物降解塑料引起的 NO3−-N 脉冲供应加剧了 Trifolium repens L. 侵袭


微塑料对植物入侵的加剧引起了广泛关注。豆类资源假说是阐明植物入侵的流行理论。我们之前的工作表明，可生物降解的微塑料 （BMP） 可以提高丛枝菌根真菌 （AMF） 的定植率据报道，AMF 可以增强根瘤菌定植。因此，我们推断 BMPs 与豆科植物共存可能导致根瘤菌定植增加，并对 N 固定进行负反馈调节。这可能导致 NO3−-N 脉冲供应，从而加剧植物入侵。随后，以 Trifolium repens L. 为入侵植物，以 Oxalis corniculata L. 为本地植物，以 1% 或 5% wt BMP 进行为期 60 天的盆栽试验，测定 AMF 定植、BMPs 降解、NO3−-N 含量和脉冲供应、根瘤菌定植、相对竞争强度、替换图和 NO3−-N 利用率。通过热图和结构方程模型阐明了其作用机制。结果表明，BMPs消耗的NO3−-N越大，AMF越能促进毛苔藓根瘤菌的定植，因此NO3−-N供应的脉冲幅度越大，因此，毛苔藓的NO3−-N利用率越高。它加剧了 T. repens 的入侵。本研究阐明了 BMPs 对根瘤菌固氮的影响，并丰富了 BMPs 加剧植物入侵机制的证据。