Nanoselenium anchored halloysite clay nanotubes/sodium alginate composites used as seed coatings to promote crop growth

The use of nanomaterials in seed coating offers great advantages, such as increasing the resistance of seeds to physical damage, promoting seed growth, and delivering essential nutrients to seeds. Herein, a functional seed coating material is obtained by anchoring selenium (Se) nanoparticles on the surface of polydopamine (PDA)-modified halloysite nanotubes (HNTs) using an in-situ synthesis method. The SA/HNTs-PDA@Se (SHPS) coating is obtained by mixing HNTs-PDA@Se with sodium alginate (SA) solution as the film-forming agent. HNTs act as supporter for Se nanoparticles to prohibit their aggregation as well as a controlled release for the Se elements. Wheat seeds are selected as a plant model to be coated, and the coating can be formed using Ca 2+ as interfacial crosslinker. HNTs improve the affinity of the composite coating solution on the smooth surface for seeds, as well as improving the hydrophilicity and mechanical property of the coating film. The composite coating improves the resistance of the seeds to physical damage, and the water absorption and water retention capacity. The SHPS coating does not affect seed germination, but rather improves the development of root systems in coated seeds. Seed coating with a nano-Se increases Se content in wheat leaves to 277.8 μg/kg, and the crop become a Se-enriched crop, which improves the quality of the crop. This work extends the application of natural HNTs in functional seed coating technique, which contributes to the research and development of controlled micronutrient delivery system using nanomaterials and nanotechnology.