配位组装型微囊与植物根系互作提高农药吸收利用率的机制研究

Coordination assembled microcapsules are novel pesticide-loaded system using chelates as wall materials formed by coordination reaction of metal and organic acid. It could increase pesticide retention on plant leaves and enhance the control effect of above-ground pests by roots application. Therefore, the interaction mechanism of plant roots and pesticides regulated by coordination microcapsules would be studied in depth through the absorption, conduction and distribution of pesticides, aimed at exploring the regulatory ways of microcapsules on the pesticides retention on plant target sites, and clarify the mechanism of improving the absorption and utilization of pesticides. Based on clothianidin as a representative pesticide and cucumber as a test crop, the effects of coordination microcapsules on morphological and physiological indexes of roots would be applied to study on the interaction mechanism of plant roots and pesticides. The regulation mechanism of coordination microcapsules on pesticide conduction would be analyzed by using the accumulation regulation of pesticides in various parts of plants and the relationship with plant metabolism. Based on the migration, distribution and residual behaviors of pesticides in edible parts, the conduction behavior and residual kinetic model of pesticides of coordination microcapsules would be established to elucidate the relationship between the pesticide retention in plant target sites and the absorption-conduction-distribution of pesticides , and clarify the main effect factor of coordination microcapsules. It is expected that the research results will provide the basic data for constructing delivery system of coordinated microcapsule pesticides, and provide a theoretical basis for pesticide reduction.

配位组装型微囊是以金属和有机酸通过配位反应形成的螯合物作为囊壁材料的一种新型的载药体系。该微囊能够在根区施药方式下提高植物叶片农药残留量，增强对地上害虫的防治效果。在此基础上，本项目从农药的吸收、传导和分布角度出发，深入研究配位微囊调控植物根系与农药互作机理，明确其对植物靶标部位农药残留量的调控途径，阐明提高农药吸收利用率的机制。以噻虫胺为代表性农药，以黄瓜为供试作物，通过配位微囊对根系形态结构和生理指标的影响探究其调控植物根系与农药互作机理；利用植株各部位农药积累规律及与植物代谢的关系分析配位微囊对农药传导的调控机制；通过农药在可食部位的迁移分布规律和残留行为，建立基于配位微囊的农药传导行为和残留动力学模型，阐明植物靶标部位农药残留量与配位微囊调控农药吸收-传导-分布的关系，明确配位微囊的主效应因子。预期研究结果为构建配位微囊农药对靶输送系统提供基础数据，为实现农药减量提供理论依据。

配位缓释颗粒剂在根区施药方式下能够提高植物叶片的农药残留量，增强对地上害虫的防治效果，但是其调控药剂在植株中的行为机制不明。本研究以藻酸钠为骨架、三价铁离子/单宁酸（Fe(Ⅲ)/TA）配位螯合物为载体材料，制备了噻虫胺缓释颗粒。与悬浮剂和颗粒剂相比，配位缓释颗粒剂对蚜虫显示出更为持久的防治效果。通过对噻虫胺的吸收、传导行为及根浓度因子、生物富集因子等参数分析，证明配位缓释颗粒剂能显著增加根系对药剂的吸收能力和植株对药剂的富集能力，提高植株对农药的利用率。通过对载体配位螯合物研究发现，载体材料具有明显的水解行为，释放游离单宁酸。单宁酸作为一种多酚化合物，提高植株自由基清除能力和根系活力，降低丙二醛和过氧化氢含量，改善植株生态状态，缓解农药的氧化胁迫，提高植物吸收和积累噻虫胺的能力。通过植物广靶代谢组学技术，发现农药施用后对植株产生较为严重的胁迫，植株黄酮醇、黄酮类生物合成等多个代谢通路发生紊乱。而加施单宁酸后，农药产生的胁迫得到缓解，黄酮类生物合成代谢路径趋于正常。. 本研究从农药利用角度出发，深入研究配位缓释颗粒剂调控植物根系与农药互作提高农药吸收利用率的行为和机理，从药剂动态监测及多个因子参数证明配位缓释颗粒处理可以显著提高根系对药剂的吸收能力和植株对药剂的富集能力，从植物生理生化和次级代谢等多角度证明配位载体材料的水解产物单宁酸能够通过改善植株生长状态和调控植物次级代谢增强植株的非生物胁迫抗性，缓解农药产生的氧化胁迫反应，从而阐释了配位缓释颗粒剂对植物靶标部位农药残留量的调控作用机理。该研究为构建配位组装缓释剂型农药对靶输送系统提供基础数据，为实现农药减量提供理论依据。