Foliar uptake and accumulation of nanoplastics and its effect on growth and physiology in selected tree seedlings

Abstract

The persistent nature of plastics, combined with inadequate waste management practices, poses a significant and escalating threat to both terrestrial and marine ecosystems worldwide. This study investigated the foliar uptake, accumulation and physiological effects of nanoplastics (NP) in seedlings of Tectona grandis, Gmelina arborea, and Macaranga peltata. Five-month-old seedlings were subjected to foliar application of NP solutions (0.1 mg L⁻¹ and 1 mg L⁻¹) for 21 days, with control plants serving as a baseline. Confocal Laser Scanning Microscopy confirmed the uptake and systemic transport of nanoplastics in leaves, stems, and roots of all species. Growth parameters, including height and collar diameter, showed significant reductions in Tectona grandis, while physiological parameters such as photosynthesis, stomatal conductance, transpiration, and chlorophyll content declined across all species, with the most pronounced effects observed at higher nanoplastic concentrations. Biochemical analyses revealed reductions in total soluble sugars, proteins, and phenolic content, particularly in Tectona grandis and Gmelina arborea, suggesting oxidative stress and metabolic disruptions. The results highlighted strong correlations between nanoplastic exposure and impaired physiological functions. These findings provide crucial insights into the species-specific responses of trees to airborne nanoplastic contamination, emphasizing the need for further research on the ecological consequences of nanoplastics in forest ecosystems. By examining these effects, the research aims to provide insights into the potential risks posed by airborne nanoplastics to plant health.