Hydroxyapatite-curcumin composites as nano-biostimulants for early-stage plant development

Global agriculture is increasingly challenged by rising food demand, limited fertile land, and crop losses due to biotic and abiotic stressors. These issues have accelerated the development of sustainable solutions such as nanofertilizers/nano-biostimulants, which aim to enhance nutrient delivery and plant resilience while reducing environmental impact. In this perspective, the present study evaluates hydroxyapatite-curcumin (HAp/Cur) nanocomposites as potential biostimulants for early-stage plant development. Curcumin (Cur) incorporation modified the morphology and dispersion of the hydroxyapatite (HAp) particles without altering its crystalline structure. Among the tested formulations, the 6.37 % Cur variant demonstrated the highest stability and retention capacity. Biological assays were conducted using Raphanus sativus and Solanum lycopersicum seeds exposed to HAp, Cur, and HAp/Cur at concentrations ranging from 100 to 1000 mg/L. In Raphanus sativus , the treatment with 100 mg/L HAp significantly improved germination and stem elongation, whereas high Cur concentrations negatively affected both parameters. In Solanum lycopersicum , germination rates remained comparable to the control, but seedlings treated with 1000 mg/L HAp/Cur exhibited increased height and reduced malformations. These findings suggest that HAp/Cur nanocomposites may serve as multifunctional agents, combining nutrient delivery and protective effects. The species-specific responses underscore the importance of tailoring nano-biostimulants formulations to individual crop requirements, contributing to more sustainable and precision-driven agricultural practices. • First study of HAp/Cur as agricultural nano-biostimulant. • Curcumin modifies morphology without altering HAp crystalline phase. • Seeds were exposed to nanomaterials for 24 h and evaluated over 14 days. • 100 mg/L HAp doubled germination and elongation in Raphanus sativus . • HAp/Cur 1000 mg/L promoted enhanced foliage in tomato seedlings.