Nitrate accumulation in lemna minor on 6 different media

Duckweed is a potential alternative protein source for food and feed. However, little is known about the nitrate accumulation in this plant. A high nitrate level in vegetables can indirectly lead to an elevated intake of nitrites and N-nitroso compounds, increasing the risk of diseases for humans and animals. This research evaluated whether duckweed grown on different media accumulates nitrate beyond legal safety levels for human and animal intake. Duckweed was grown on (i) rainwater, and (ii) three synthetic media containing different nutrient levels. Furthermore, (iii) biological effluent of swine manure treatment and (iv) aquaculture effluent from pikeperch production were used, as these are potential media for closing nutrient loops in the agriculture sector. It was found that nitrate levels increased with the increasing availability of macronutrients in the water, and pH showed a particularly strong negative correlation with the nitrate levels in duckweed. Nevertheless, nitrate content of duckweed never exceeded 530 mg NO3 kg-1 fresh weight. To conclude, duckweed’s nitrate content was below safety limits for human consumption in all tested growing media; however, a potential risk for ruminants was observed as these are more sensitive to nitrate conversions in their gastro-intestinal track. The first tab contains information on the units and the measured parameters in both the water and duckweed.浮萍（Duckweed）是一种可用于食品与饲料生产的潜在替代蛋白源。然而，目前学界对该植物体内的硝酸盐积累情况尚缺乏足够了解。蔬菜中的硝酸盐水平过高时，会间接导致亚硝酸盐及N-亚硝基化合物的摄入量上升，增加人类与动物的患病风险。本研究旨在评估不同培育基质中生长的浮萍，其硝酸盐积累量是否超出人类与动物摄入的法定安全限值。实验中，浮萍分别在以下四类基质中培育：(i) 雨水；(ii) 三种营养水平各异的合成培养基；(iii) 猪粪处理生物出水；以及(iv) 梭鲈养殖水产废水。此类基质均可用于实现农业领域的养分循环闭环。研究结果显示，水体中大量营养元素的可获得性越高，浮萍的硝酸盐水平也随之上升；而水体pH值与浮萍硝酸盐水平呈现出极强的负相关关系。但所有实验组中，浮萍的硝酸盐含量始终未超过530 mg NO₃⁻·kg⁻¹ 鲜重。综上，所有受试培育基质中生长的浮萍，其硝酸盐含量均符合人类食用的安全限值；但反刍动物存在潜在暴露风险，因其胃肠道内的硝酸盐转化过程对硝酸盐水平更为敏感。 首个数据标签页包含了水体与浮萍样品的检测参数及对应单位信息。