Seed contaminants: an overlooked pathway for the introduction of non-native plants in Sardinia (Italy)

The accidental introduction of alien plants through contaminated seed is a source of new incursions and subsequent invasions that can impact natural habitats, agriculture and forestry. While seed lots for agricultural crops are often well regulated through a certification process, the trade of many other types of seeds is largely unregulated. Here, we evaluate the risk of seed lots trade as a pathway for invasive alien plant species in Sardinia (Italy), by identifying and quantifying the presence of contaminant species. The study included uncertified commercial seeds as well as the ones sold as pet feed. We randomly sampled 39 seed packets, from multiple sources, including novel forage crops under experimental testing (Fc), flower mixtures (Fm), recreational lawn mixtures (Lm) and pet feed (Pf). Germination and viability were analysed on the seed commodity of Pf. A total of 231 contaminant species was found, belonging to 88 genera and 34 families. Moreover, among the contaminants, the non-native invasive agricultural weeds <i>Amaranthus</i> sp. pl. and <i>Echinochloa</i> sp. pl. were found. Our results showed that unregulated seed contaminants are associated with a high risk of non-native plants entry and their potential establishment in Sardinia.通过受污染种子意外引入外来植物，是引发新的入侵事件及后续生物入侵的源头之一，此类入侵会对自然栖息地、农业与林业造成负面影响。尽管农作物种子批次通常会通过认证流程得到严格监管，但诸多其他类型种子的贸易却基本处于无监管状态。本研究以意大利撒丁岛为研究区域，通过识别并量化污染物种的存在情况，评估种子批次贸易作为外来入侵植物物种传播途径的风险。本次研究纳入了未获认证的商用种子，以及作为宠物饲料售卖的种子。研究人员从多个来源随机抽取了39份种子包装，涵盖试验测试中的新型饲用作物（Fc）、花卉混合种子（Fm）、休闲草坪混合种子（Lm）以及宠物饲料用种子（Pf）。针对宠物饲料用种子（Pf）的商品种子，研究人员分析了其发芽率与活力水平。本次研究共发现231种污染物种，隶属于88个属、34个科。此外，在污染物种中还发现了非本土入侵性农业杂草<i>Amaranthus</i> sp. pl.与<i>Echinochloa</i> sp. pl.多个物种。研究结果表明，未受监管的种子污染物与外来植物入侵撒丁岛的高风险存在关联，且这些外来植物有可能在当地定殖。