# Effect of Zinc Oxide Nanoparticles on the Physiological and Biochemical Responses of Coffea arabica L. Exposed to Glyphosate

## TL;DR

Zinc oxide nanoparticles help protect coffee plants from the harmful effects of glyphosate by improving their physiological and biochemical responses.

## Contribution

This study demonstrates the protective effect of ZnO NPs against glyphosate-induced phytotoxicity in coffee plants.

## Key findings

- ZnO NPs improved photosynthetic efficiency and chlorophyll content in glyphosate-exposed coffee plants.
- Application of ZnO NPs reduced oxidative damage markers like H2O2 and MDA in both leaves and roots.
- ZnO NPs enhanced nutrient accumulation and membrane integrity under glyphosate exposure.

## Abstract

Glyphosate is widely used for weed control in coffee but can induce physiological alterations due to its lack of selectivity, and indirect spray drift can cause adverse effects, potentially increasing biological impacts upon exposure. In this study, we evaluated the attenuating effect of foliar-applied zinc oxide nanoparticles (ZnO NPs) on C. arabica var. Geisha seedlings exposed to simulated spray concentrations of glyphosate (3.6 and 17.9 g ae L−1). Exposure caused a marked reduction in chlorophyll content, stomatal conductance, and net photosynthesis, while simultaneously promoting an increase in H2O2, MDA, and proline accumulation, reflecting a pronounced redox imbalance and oxidative damage associated with the production of reactive oxygen species (ROS). In contrast, the application of ZnO NPs improved photosynthetic efficiency, increased chlorophyll content, stabilized stomatal aperture, and reduced H2O2 and MDA levels in both leaves and roots. Moreover, it enhanced nutrient accumulation, ensuring greater membrane integrity and more efficient ion transport systems under glyphosate exposure. Overall, the ZnO NPs exhibited a notable protective effect by reducing glyphosate-induced phytotoxicity and strengthening the physiological tolerance of C. arabica. These findings support their potential as a sustainable tool to protect coffee crops from glyphosate exposure.