Nanoparticle innovations: impact of biogenic CaP nanoparticles in mitigating the adverse effects of excessive nitrate application

Aims

The overuse nitrogen fertilizer has resulted in significant environmental pollution and may also affect the ability of plants to withstand stress and productivity. The goal of this study was to create a nanofertilizer that may improve the resistance of lupine (Lupinus termis L) nitrate stress while simultaneously releasing a micronutrient that supports plant growth.

Methods

Calcium phosphate nanoparticles (CaP-NPs) were created via Jania rubens extract and sprayed on lupine plants as a foliar spray at various dosages (0, 25, 50, and 100 mg/L) to mitigate the harmful effects of high nitrate stress (200 mM nitrate) on the seedling stage of lupine plants.

Results

The biogensis CaP-NPs were characterised to have a spherical form with a size of 29 ± 3.2 nm. The findings demonstrated that, in contrast to the control, nitrate stress negatively affected the growth metrics of lupines; however, foliar spraying with CaP-NPs increased these parameters during nitrate stress. Moreover, treatment with CaP-NPs greatly reduced the increased levels of indicators of oxidative stress (MDA, H₂O₂, proline, nitrate-nitrogen (NO₃⁻⁻N), and ammonium-nitrogen (NH₄⁺-N)). Additionally, the administration of CaP-NPs under conditions of elevated nitrate stress induced the activity of antioxidant enzymes (peroxidase (POD), ascorbate peroxidase (APX), polyphenol oxidase (PPO), and phenylalanine (PAL)) as well as non-enzymatic markers such as total antioxidant capacity (TAC), total flavonoid content, total phenolic content, ascorbic acid, and glutathione. The administration of CaP-NPs resulted in an increase in the expression of antioxidant genes, including ferritin (FER1), phenylalanine (PAL), catalase2 (CAT2), superoxide dismutase1 (SOD1), chalcone synthase (CHS), and flavonol synthase (FLS). The highest level of upregulation was observed at 100 mg/L CaP-NPs.

Conclusion

Foliar CaP-NPs nanofertilizer application in agriculture may increase yield while reducing the harmful effects of nitrate stress on plants. Thus, our work provides a solid basis for further investigations aimed at assessing the substitution of CaP nanofertilizers for traditional Ca²⁺ or P fertilizers to mitigate the deleterious effects of nitrate stress and improve lupine output.