Novel polymeric nanoparticles as nanofertilisers for alkaline iron-deficient conditions

Background and aims

Iron deficiency chlorosis (IDC) is a nutritional disorder impacting plants and is prevalent in calcareous alkaline soils, corresponding to 30% of the world's arable land. IDC compromises iron uptake in crops such as soybean (Glycine max). To improve the effect of iron fertilisers, we sought to develop a nanotechnology-based intervention using polymeric nanoparticles (NPs) loaded with Fe(dmpp)₃.

Methods

Nanoparticles were loaded with a fluorophore to understand their uptake by soybean. Nanoparticles’ physicochemical and release properties were examined. The work comprises a seed soaking study considering untreated plants, and Fe(dmpp)₃ solutions or nanosuspensions (NSs) (10 and 20 µM).

Results

Plants treated with 20 µM NS showed an improvement in morpho-physiological traits and an increase in relevant gene expression vs control. They reached V1 stage 2.5 days faster and V3 2.8 days faster; had a 26% higher SPAD values at stage V3; developed roots that had 39% higher total fresh weight and shoots that were 26% heavier; and registered a 2.25-fold increase in root IRT1 expression and a 3.37-fold increase in leaf ferritin expression. Treatment with 10 µM NS led to a 3.31-fold increase in ferritin expression vs control and a 2.49-fold increase vs Fe(dmpp)₃ solution at 10 µM.

Conclusions

The results illustrate the potential of NPs as a seed-soaking agent, promoting plant growth, reducing IDC, and activating molecular-level iron availability responses. Notably, this is the first study attempting to monitor the mobility of fluorescent NPs in soybean plants and the first in employing NPs as nanocarriers of Fe(dmpp)₃.