Silver nanoparticles (AgNP) exhibit size and concentration dependent toxicity to terrestrial plants, especially crops. AgNP exposure could decrease seed germination, inhibit seedling growth, affect mass and length of roots and shoots. The phytotoxic pathway has been partly understood. Silver (as element, ion or AgNP) accumulates in roots/leaves and triggers the defense mechanism at cellular and tissue levels, which alters metabolism, antioxidant activities and related proteomic expression. Botanical changes (either increase or decrease) in response to AgNP exposure include reactive oxygen species generation, superoxide dismutase activities, H2O2 level, total chlorophyll, proline, carotenoid, ascorbate and glutathione contents, etc. Such processes lead to abnormal morphological changes, suppression of photosynthesis and/or transpiration, and other symptoms. Although neutral or beneficial effects are also reported depending on plant species, adverse effects dominate in majority of the studies. More in depth research is needed to confidently draw any conclusions and to guide legislation and regulations.

中文翻译：

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银纳米粒子对种子发芽和陆生植物生长的植物毒性作用。

银纳米颗粒（AgNP）对陆生植物（尤其是农作物）表现出大小和浓度依赖性的毒性。AgNP暴露可减少种子发芽，抑制幼苗生长，影响根和芽的质量和长度。植物毒性途径已被部分理解。银（作为元素，离子或AgNP）在根/叶中积累并触发细胞和组织水平的防御机制，从而改变新陈代谢，抗氧化活性和相关的蛋白质组表达。AgNP暴露引起的植物变化（增加或减少）包括活性氧的产生，超氧化物歧化酶活性，H2O2水平，总叶绿素，脯氨酸，类胡萝卜素，抗坏血酸和谷胱甘肽的含量等。这些过程导致异常的形态变化，抑制光合作用和/或蒸腾作用，和其他症状。尽管还报道了取决于植物种类的中性或有益作用，但在大多数研究中，不良反应占主导地位。需要进行更深入的研究，以自信地得出任何结论并指导立法和法规。