How to improve crop photosynthesis more efficiently using nanomaterials: Lessons from a meta-analysis

Nanomaterials (NMs) have been increasingly used to improve crop photosynthesis under diverse environments, However, the factors affecting the response of crop photosynthesis to NMs still remain insufficiently known. In the present study, a meta-analysis was conducted to investigative the NM effects on leaf photosynthesis-related parameters in maize, rice and wheat plants. Our results suggest that leaf photosynthetic rate ( A ) can be significantly improved by NMs through enhanced stomatal conductance, leaf transpiration rate, leaf electron transport rate, and chlorophyll b content, and the NM effects on A were similar among different crop species. We also found that positive effects of NMs on A were stronger under drought and salt stresses than under heavy metal, nanoplastic and normal (no abiotic stress) conditions, while the response of A to NMs under heat stress still needs further verification due to the limited studies, which remains critical knowledge gap requiring further research. Additionally, our present findings demonstrate that non-metallic NMs and seed application method are more beneficial for enhancing A than metallic NMs and other application methods, respectively. More importantly, our results indicate that the impacts of NMs on A observed under laboratory conditions should be carefully examined under field conditions prior to large-scale application. Besides, decreasing the application frequency of NMs with small size and low dosage has the potential to maximize crop A while also reducing economic and environmental costs. Our current findings should prove beneficial for future studies aimed at enhancing crop photosynthesis and yields under varying environments through the application of NMs. • Positive effects of NMs on A were stronger under drought and salt stresses than under other conditions. • Impacts of NM on A should be carefully examined under field conditions prior to large-scale application. • Decreasing the application frequency of NMs with small size and low dosage has the potential to maximize crop A .