Synthesis and optimization of urea-loaded CaCO3 nanoparticles for foliar fertilization and growth enhancement in eggplant (Solanum melongena)

Abstract

Eggplant is an agriculturally important crop widely cultivated in the tropical and subtropical regions because of its nutritional and economical significance. Improving crop productivity and nutrient utilization efficiency has become increasingly important to address global food security challenges and sustainable agricultural development. In the present study, urea-loaded CaCO 3 nanoparticles were synthesized through a simple precipitation method and characterized using XRD, FTIR, SEM, EDX, TEM DLS, TGA, and BET analysis to evaluate their structural, morphological, elemental, and surface chemical properties. Controlled nitrogen release behavior of the synthesized nanofertilizer were also investigated under aqueous conditions. The release kinetics was consistent with the Fickian diffusion ( n  = 0.45, R 2  = 0.98) according to Korsmeyer-Peppas model. Pot experiments were performed using foliar application of the synthesized nanoparticles at concentrations of 1,000, 2000, and 3,000 ppm in eggplants. The results were compared with untreated, DAP-treated, and urea-treated groups. Morphological parameters, including the shoot length, root length, leaf area, root/shoot number, and fruit weight were evaluated together with biochemical and physiological attributes such as chlorophyll content, calcium accumulation, total titratable acidity (2.55 ± 0.15%), and total phenolic content (87.7 ± 3.1 μg GAE/g). The synthesized nanoparticle exhibited gradual nitrogen release behavior with improved plant growth and biochemical performance, particularly under the NF 3000 treatment. Overall the plant response followed the order untreated < DAP < urea < urea-loaded CaCO 3 nanofertilizer, indicating the potential of the synthesized material for improved nutrient delivery under foliar application conditions.