Recent advances in nano-priming induced plant growth promotion and environmental stress tolerance

The increasing demand for sustainable agriculture has propelled researchers to envision novel technological innovations. In this situation, the implementation of nanoparticles eventually gained huge importance and proved to be beneficial in the field of sustainable agriculture. To date, there have been numerous reports that have focused on utilizing the nanotechnological approach for positively influencing plant growth, development, and yield-associated parameters. Over the years there have been several successful applications of nanoparticles to mitigate the toxic effects imposed by abiotic and biotic stress factors on plants. Among the three major approaches of nanoparticle application to plants, seed priming has played an important role in plant growth promotion owing to its ability to activate signaling pathways concerned with phytohormone and ROS synthesis. So far, the reports available on the role of nano-priming in boosting plant growth and tolerance against environmental stress have been mostly associated with Zn, Fe, Cu, and other essential micronutrients. But in recent years application of metallic and non-metallic nanoparticles like silver, gold, platinum, titanium, and carbon nanotubes is also worth mentioning. The outcome of nano-priming is also subject to the appropriate concentration, charge, and size of NPs used. Besides, nano-priming can elicit a plethora of physiological, biochemical, and molecular responses in the germinating seeds that require proper understanding. Hence this review aims to document the progress made in the nano-priming research and pave the way for other advancements that can be made in the future.