**8. Conclusion and prospective**

Various abiotic factors are damaging the plants in terms of growth and development leading to a reduction in yield and deteriorating the quality. Applications of NPs have been proven very protective as they stimulate germination, growth, and improve yield. They increase tolerance in plants as they enhance the uptake of water and nutrients. They are capable to metabolize starch reserves in plant cells. They stimulate the process of photosynthesis and alter levels of phytochromes and modulate oxidative stress.

Although various studies suggest the beneficial roles of NPs in plants but the molecular basis of the actual mechanism is still unknown. Further elucidation on this mechanism may generate the smart NPs for the production of crops sustainable to the environment. In addition, their interaction with signaling molecules is also required to be explored. The economic stability of the use of NPs in agriculture is important as silver and gold nanoparticles costs very expensive. Understanding their mode of action, toxicity limits, signaling, and translocation; hence cheaper NPs may be used as an alternative.
