The persistent global challenge of food security necessitates innovative strategies to enhance fundamental crop productivity, specifically by optimizing photosynthesis—the process governing energy conversion and biomass production. This study reviews the transformative potential of Copper-based Nanomaterials (Cu-NMs), including metallic Copper Nanoparticles (CuNPs) and Copper Oxide Nanoparticles (CuONPs), as a dual-mechanism approach to significantly enhance plant photosynthetic performance and light harvesting efficiency. Cu-NMs operate through two primary pathways. First, they function as advanced nano-fertilizers, supplying the essential micronutrient copper in a highly bioavailable form. Copper is critical for the photosynthetic electron transport chain (PETC) as a key component of plastocyanin. Optimal concentrations of Cu-NMs facilitate the increase of photosynthetic pigment content (chlorophyll a and b) and improve the quantum yield of Photosystem II (Fv/Fm), thereby boosting the net photosynthetic rate and overall plant growth. This regulatory effect is concentration-dependent, where low, targeted doses are beneficial, but excessive concentrations induce phytotoxicity and oxidative stress. Metallic CuNPs offer a physical enhancement mechanism through Localized Surface Plasmon Resonance (LSPR). This unique optical property allows for the coherent oscillation of free electrons on the nanoparticle surface, generating intense localized electromagnetic fields that enhance the absorption and scattering of light within the plant's photosynthetic tissues. This plasmonic effect serves as a potential mechanism to improve the utilization of incident solar radiation, thereby augmenting light harvesting kinetics. The dual action of Cu-NMs—biochemical support for the PETC and plasmonic enhancement of light capture—offers a potent strategy for agricultural intensification. This review synthesizes current findings, highlighting the necessity for precise application protocols to leverage the benefits of Cu-NMs while mitigating the risks associated with dose-dependent toxicity, guiding future research toward safe and sustainable nanobiotechnology applications in crop science. • CuNMs enhance photosynthesis by improving light absorption, electron transport, and ATP generation. • Localized Surface Plasmon Resonance (LSPR) broadens light absorption for higher quantum efficiency. • CuNMs mitigate oxidative stress by neutralizing ROS and activating antioxidant enzymes like SOD. • Used as nano-fertilizers, CuNMs boost plant growth, biomass production, and stress resilience. • Green synthesis of CuNMs using plant extracts and microorganisms is eco-friendly and cost-effective.
Yadav et al. (Wed,) studied this question.