Dose-Dependent Effects of Zinc Oxide Nanoparticles on Growth, Antioxidative Enzymes, and Yield of Pearl Millet: Research Article

Rajneesh Kumar  Prajapati; Amit Kumar  Dixit; Girish Chandra Pathak

doi:10.21276/pt.2025.v2.i4.9

Authors

Rajneesh Kumar Prajapati University of Lucknow, Lucknow, India Author https://orcid.org/0009-0002-9494-9403
Amit Kumar Dixit University of Lucknow, Lucknow, India Author https://orcid.org/0009-0003-8265-5157
Girish Chandra Pathak University of Lucknow, Lucknow, India Author https://orcid.org/0009-0001-9275-9633

DOI:

https://doi.org/10.21276/pt.2025.v2.i4.9

Keywords:

Antioxidative enzymes, Foliar application, Sustainable agriculture, Zinc fertilizer, Zinc oxide nanoparticles

Abstract

Zinc is an essential micronutrient required for optimal plant growth, metabolism, and yield; however, zinc deficiency remains a major constraint to cereal production under intensive agricultural systems. Recent advances in nanotechnology have highlighted zinc oxide nanoparticles (ZnO-NPs) as a promising alternative to conventional Zn fertilizers due to their enhanced solubility, bioavailability, and targeted delivery. The present study evaluated the dose-dependent effects of ZnO-NPs on growth performance, antioxidative enzymes activity, and yield attributes of pearl millet [Pennisetum glaucum (L.) R. Br.]. Plants were treated with graded concentrations (0.001, 0.01, 0.1, 1, 2 and 10 ppm) of ZnO-NPs through foliar application, and their effects were compared. Plants exhibited a concentration-dependent response to ZnO nanoparticle application, with significant enhancement in vegetative growth, chlorophyll biosynthesis, and enzymatic antioxidant defense up to 2 ppm. However, at higher concentrations (10 ppm), vegetative growth and chlorophyll biosynthesis declined, indicating the onset of phytotoxic effects. The application of ZnO nanoparticles at 2 ppm was the most effective treatment, significantly enhancing shoot and root biomass, chlorophyll content, tiller production, panicle weight, and seed weight compared to other concentrations. Growth parameters, including plant height, biomass accumulation, and leaf area, were significantly enhanced at optimal concentrations of ZnO nanoparticles (ZnO-NPs). Furthermore, the activities of key antioxidant enzymes—superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD)-were markedly increased, indicating improved regulation of oxidative stress and enhanced cellular protection. However, higher doses of ZnO nanoparticles (ZnO-NPs) led to a decline in physiological performance, indicating potential phytotoxic effects at excessive concentrations. Yield attributes, such as grain weight and panicle length, were optimized at moderate ZnO-NP application rates. Overall, the findings demonstrate that judicious application of ZnO-NPs can improve growth, antioxidant defense, and yield of pearl millet, highlighting their potential role in sustainable micronutrient management.

Author Biographies

Rajneesh Kumar Prajapati, University of Lucknow, Lucknow, India

Plant Nutrition and Stress Physiology Laboratory, Department of Botany
Amit Kumar Dixit, University of Lucknow, Lucknow, India

Plant Nutrition and Stress Physiology Laboratory, Department of Botany
Girish Chandra Pathak, University of Lucknow, Lucknow, India

Plant Nutrition and Stress Physiology Laboratory, Department of Botany

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