Tailoring Ca-Based Nanoparticles by Polyol Process for Use as Nematicidals and pH Adjusters in Agriculture

The remarkable progress in nanotechnology has extended the application of inorganic nanoparticles (NPs) in the agriculture sector, as both economically sustainable and environmentally sound alternatives. Root knot nematodes are undoubtedly a foremost problem of agriculture, and research strives to develop effective materials to tackle this issue. Herein, the microwave-assisted selective polyol synthesis of different compositions of Ca-based NPs, Ca(OH)2, Ca(OH)2/CaCO3, and CaCO3 is reported and the products were evaluated as nematicides and pH adjusters. Two precursors (CaCl2 and Ca(NO3)2) and three polyols (1,2-propylene glycol (PG), tetraethylene glycol (TEG), polyethylene glycol (PEG 8000)) that differ in their redox potential have been utilized to provide selectivity over composition. On the basis of the utilized polyols, NPs are produced as inorganic/organic hybrid formulations with a biocompatible organic coating that provides increased colloidal stability and controlled release of active components. Characterization of NPs has been carried out by XRD, TGA, FTIR, TEM, and pH-metry. Each composition exhibited different pH changing ability, an essential feature for agrochemical applications. The in vitro nematicidal activity of Ca(OH)2, Ca(OH)2/CaCO3, and CaCO3NPs was evaluated on second stage juveniles (J2) of two Meloidogyne species (Meloidogyne incognita and Meloidogyne javanica) based on nematode paralysis experiments. Results unveiled nematicidal activity for all evaluated Ca-based NPs, while Ca(OH)2 and CaCO3 NPs appeared to be the most and the least effective ones, respectively. The nematicidal effect appears to be boosted by the release of [OH]− anions, as indicated by pH-metric measurements, displaying the crucial role of [OH]− anions in their nematicidal activity.