Dynamic microbial regulation of triiron tetrairon phosphate nanomaterials in the tomato rhizosphere

Abstract

In this study, microbial dynamics in the tomato rhizosphere was explored at seedling, flowering, and mature stages after soil was amended with 50 mg kg⁻¹ triiron tetrairon phosphate nanomaterials (Fe₇(PO₄)₆ NMs) and conventional ion fertilizer. It was revealed that 50 mg kg⁻¹ of Fe₇(PO₄)₆ NMs resulted in a significant increase in the relative abundances of Rhodanobacter, Sphingomonas, Gemmatimonas, Flavisolibacter, and Ramlibacter by 35.7–136.0% in tomato rhizospheres at the seedling stage. These beneficial microorganisms involved in nutrient uptake helped the seedling plant to grow better. After growing to the flowering stage, the relative abundance of Pseudomonas, Mesorhizobium, Sphingomonas, and Gemmatimonas increased by a range 12.6–324.0%, expediting nutrient accumulation and initiating flower formation. The pollen length and ovule size of the flowers were also increased owing to increased photosynthesis and sucrose transportation to the flowers. Furthermore, Fe₇(PO₄)₆ NMs enriched the abundance of Nitrospira, Sphingomonas, Massilia, Bryobacter, Chthoniobacter, RB41, and Rubellimicrobium at the mature stage, contributing to enhanced soil fertility as evidenced by a notable increment in the availability of phosphorus and potassium by 38.0% and 18.7%, respectively. Additionally, the utilization of Fe₇(PO₄)₆ NMs led to a remarkable improvement in fruit productivity and quality, which was indicated by a substantial increase in fruit weight by 174.0%, and in the content of soluble sugar, vitamin C, and amino acids by a range 42.2–103.0%. Our study provides an effective nano-enabled strategy for regulating rhizobacteria to meet specific functional demands during different developmental stages, thereby enhancing crop productivity.