Interaction of metal oxide nanoparticles with higher terrestrial plants: Physiological and biochemical aspects

• Consistent adverse effects on plant growth by nCuO.
• Delay in the reproductive development of plants by nCeO2.
• Controversial effects of nZnO/nTiO2 depend on exposure conditions and plant species.
• Multigenerational, geno-type-specific, and combined pollution studies in future.

Multiple applications of metal oxide nanoparticles (MONPs) could result in their accumulation in soil, threatening higher terrestrial plants. Several reports have shown the effects of MONPs on plants. In this review, we analyze the most recent reports about the physiological and biochemical responses of plants to stress imposed by MONPs. Findings demonstrate that MONPs may be taken up and accumulated in plant tissues causing adverse or beneficial effects on seed germination, seedling elongation, photosynthesis, antioxidative stress response, agronomic, and yield characteristics. Given the importance of determining the potential risks of MONPs on crops and other terrestrial higher plants, research questions about field long-term conditions, transgenernational phytotoxicity, genotype specific sensitivity, and combined pollution problems should be considered.