Invasive plants are a major threat to biodiversity and may adversely affect food security. Clonal integration enables the sharing of resources between connected ramets and can enhance plant performance in many invasive species. However, few studies have examined the role of clonal integration when weeds are exposed to plant growth regulators (PGRs). PGRs are used extensively in agriculture and may affect nearby weeds through soil leaching, erosion and runoff. Our aim was to investigate the effects of clonal integration on growth in a noxious weed, Alternanthera philoxeroides (alligator weed), in response to two PGRs frequently used in agriculture, gibberellins (GAs) and paclobutrazol (PAC). Ramets of A. philoxeroides were propagated in the greenhouse, and treated with PGRs. PGRs were applied to the older ramets (i.e. ‘basal’ part), with half of the plants having the stems between the apical (younger) and basal parts left connected, while the remaining plants had the stems between the two parts severed. Following the growing period, plants were measured for growth traits. We found that GA and PAC had contrasting effects on plant growth. GA significantly promoted above-ground growth of the apical ramets via clonal integration. Alternatively, PAC inhibited above-ground growth in the basal and apical parts, and enhanced below-ground growth of the basal and apical ramets through clonal integration. Our results highlight how clonal integration can promote growth in A. philoxeroides following the application of PGRs, which is likely an important mechanism for this species to invade new environments.
摘要：
植物生长调节剂通过克隆整合对空心莲子草顶端和基部生长的不同作用
入侵植物不仅对全球生物多样性造成了巨大的威胁，同时也严重影响了农业生产与粮食安全。克隆整合使得相连植株进行资源共享，能促进入侵植物的生长从而获得优势。然而，入侵杂草 在植物调节剂(plant growth regulators, PGRs)影响下的克隆整合作用则很少有报道。PGRs被广泛应用于 农作物生产上，并能通过土壤淋溶、侵蚀和径流作用，影响分布在作物附近的农田杂草的生长。本 研究采用两种PGRs赤霉素(gibberellins, GA)和多效唑(paclobutrazol，PAC)处理恶性入侵杂草空心莲子草 (Alternanthera philoxeroides)基端，并保持或者通过剪切达到控制基端与顶端的连通，从而探究克隆整合作用在空心莲子草响应两种农业常用PGRs中的作用。研究结果表明，GA和PAC对空心莲子草生长的作用相反。GA通过克隆整合作用显著促进顶端植株的地上生长。相反地，PAC显著抑制基端和顶端的地 上生长，但是能够通过克隆整合作用显著促进基端和顶端的地下生长。这些研究结果解释了克隆整合作用能促进PGRs对空心莲子草生长的促进作用，这很可能是外来杂草能够成功入侵人为干扰较多的农业生态系统的重要原因之一。
关键词:
农田杂草,
外来克隆植物,
表型特征,
植物激素,
植物入侵
