The dicamba-resistant cropping system was developed to be used as a tool to control multiple-resistant weed species, particularly Palmer amaranth (Amaranthus palmeri S. Watson). However, dicamba applications have resulted in off-target movement of the herbicide to susceptible neighboring vegetation, with frequent damage to non–dicamba resistant soybean [Glycine max (L.) Merr.]. Pod malformation and subsequent auxin-like injury to progeny is common when parent soybean plants are exposed to the herbicide post-flowering. Yet no publication to date has conveyed the presence of dicamba in seed. The objective of this study was to determine whether dicamba exists and at what quantities inside soybean seed following a low-dose exposure in the pod-filling stage using radiolabeled herbicide as a tracer. Non–dicamba resistant soybean plants were grown in the greenhouse until the pod-filling growth stage and then treated with 2.8 g ae ha−1 of dicamba (1/200 of the recommended rate of 560 g ae ha−1). Immediately afterward, [14C]dicamba (approximately 6.4 kBq per plant) was applied to the adaxial surface of one trifoliate leaf located in the midportion of each plant. The greatest amount of [14C]dicamba recovered was in seeds and in pods, and these plant parts accumulated 44% and 38% of the total absorbed, respectively. Chromatography results showed that the totality of the [14C]dicamba present in the soybean seeds was in the phytotoxic form, except for a single sample, in which one metabolite was detected (possibly 5-hydroxy dicamba). Precautions should be taken to avoid dicamba exposure to sensitive soybean fields, especially those dedicated to seed production, as this may result in low seed quality and symptomology on progeny plants.

中文翻译：

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麦草畏在大豆中的易位和在种子中的积累

开发抗麦草畏种植系统是为了用作控制多重抗性杂草物种的工具，特别是棕榈苋菜。苋菜S.沃森）。然而，麦草畏的应用导致除草剂脱靶移动到易感的邻近植被，并经常损害非麦草畏抗性大豆。最大甘氨酸(L.) Merr.]。当亲本大豆植物在开花后暴露于除草剂时，豆荚畸形和随后对后代的生长素样损伤很常见。然而，迄今为止没有任何出版物表明种子中存在麦草畏。本研究的目的是确定是否存在麦草畏以及在豆荚灌浆阶段使用放射性标记的除草剂作为示踪剂进行低剂量暴露后大豆种子内的麦草畏含量。在温室中种植非麦草畏抗性大豆植物直至结荚生长阶段，然后用 2.8 g ae ha 处理-1麦草畏（推荐剂量 560 g ae ha 的 1/200-1）。紧接着，[14C]麦草畏（每株植物约6.4 kBq）施用于位于每株植物中部的一片三叶叶的近轴表面。最大量 [14C]麦草畏回收在种子和豆荚中，这些植物部分分别积累了总吸收量的 44% 和 38%。色谱结果表明，[14存在于大豆种子中的 C]麦草畏呈植物毒性形式，除了在单个样品中检测到一种代谢物（可能是 5-羟基麦草畏）。应采取预防措施，避免麦草畏暴露于敏感的大豆田，尤其是那些专门用于种子生产的田地，因为这可能导致种子质量低下，后代植物出现症状。