Novel polymeric nanoparticles as nanofertilisers for alkaline iron-deficient conditions

Abstract

Iron deficiency chlorosis (IDC) is a nutritional disorder adversely affecting plant health and crop yields, particularly in the approximately 30% of the world's arable land, which is composed of calcareous alkaline soils. The condition compromises effective iron uptake in crops such as soybeans (Glycine max), leading to chlorosis and stunted growth. This study introduces a novel nanotechnology-based intervention utilising 3-hydroxy-4-pyridinones (3,4HPO) iron (III) chelates-loaded nanoparticles (NPs) to address IDC, offering a controlled and sustainable release of iron and demonstrating effectiveness in enhancing plant health and chlorophyll content. Counteracting the limitations of traditional iron chelates like EDTA, which suffer from poor biodegradability and potential environmental risks, the 3,4-HPO chelates, such as Fe(mpp)3 and Fe(dmpp)3, emerge as a sustainable alternative, showing increased iron bioavailability with minimal toxicity. Comparative analysis highlights the superior efficiency of these chelates over conventional treatments in preventing IDC symptoms, fostering greener, more robust plant growth, and higher iron accumulation. Innovative nanocarriers were developed for fertiliser delivery, capitalising on the nano-porous structure of plant roots and leaves, with the aim of enhancing nutrient uptake and correcting IDC. The research progressed through the production, optimisation, and characterisation of rhodamine B-labelled polymer-based NPs. Their uptake by soybean plants was assessed, identifying the most favourable characteristics for plant absorption. Building on this, the methodology was adapted to encapsulate the iron chelates Fe(dmpp)3 and Fe(mpp)3 within the NPs. Subsequent in vivo studies utilised Fe(dmpp)3 NPs for seed priming in soil, evidencing significant improvements in chlorophyll content, growth rates, and biomass in iron-deficient conditions. Furthermore, the study's foray into genetic expression analysis revealed upregulated iron-related genes, pointing to a profound molecular impact of NP treatment and an improved mechanism for iron transport and storage. The findings indicate that Fe(dmpp)3-loaded NPs not only alleviate IDC but also present a potential paradigm shift in the fertiliser industry, promoting more sustainable and efficient agricultural practices. The implications extend beyond increased crop yields, suggesting that engineered NP treatments could be instrumental in the future of agriculture, integrating environmental responsibility with enhanced productivity.

Date of Award	25 Jan 2024
Original language	English
Awarding Institution	Universidade Católica Portuguesa
Supervisor	Marta Vasconcelos (Supervisor) & Tânia Alexandra Fernandes de Sousa Moniz Abreu (Co-Supervisor)