Silicate-based mineral materials promote submerged plant growth: Insights from plant physiology and microbiomes.

Restoring submerged plants naturally has been a significant challenge in water ecology restoration programs. Some silicate-based mineral materials have shown promise in improving the substrate properties for plant growth. While it is well-established that silicate mineral materials enhance submerged plant growth by improving salt release and reducing salt stress, the influence of rhizosphere microorganisms on phytohormone synthesis and key enzyme activities has been underestimated. This study focused on two typical silicate mineral materials, bentonite and maifanite, to investigate their effects on Myriophyllum oguraense from both plant physiology and microbiome perspectives. The results demonstrated that both bentonite and maifanite regulated the synthesis of phytohormones such as gibberellin (GA) and methyl salicylate (MESA), leading to inhibition of cellular senescence and promotion of cell division. Moreover, these silicate mineral materials enhanced the activity of antioxidant enzymes, thereby reducing intracellular reactive oxygen species levels. They also optimized the structure of rhizosphere microbial communities, increasing the proportion of functional microorganisms like Nitrospirota and Sva0485, which indirectly influenced plant metabolism. Analysis of sediment physicochemical properties revealed increased rare earth elements, macronutrients, and oxygen content in pore water in the presence of silicate materials, creating favorable conditions for root growth. Overall, these findings shed light on the multifaceted mechanisms by which natural silicate mineral materials promote the growth of aquatic plants, offering a promising solution for restoring aquatic vegetation in eutrophic lake sediments.