Average number of days to callus initiation.

The current study focuses on the usage of bio synthesized zinc oxide nanoparticles to increase the tissue culture efficiency of important forage grass Panicum virgatum. Zinc being a micronutrient enhanced the callogenesis and regeneration efficiency of Panicum virgatum at different concentrations. Here, we synthesized zinc oxide nanoparticles through Cymbopogon citratus leaves extract to evaluate the effect of zinc oxide nanoparticles on plant regeneration ability in switchgrass. X-ray diffraction (XRD) and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) validate phase purity of green synthesize Zinc oxide nanoparticles whereas, electron microscopy (SEM) has illustrated the average size of particle 50±4 nm with hexagonal rod like shape. Energy dispersive spectroscopy X-ray (EDS) depicted major peaks of Zn (92.68%) while minor peaks refer to Oxygen (7.32%). ZnO-NPs demonstrated the incredibly promising results against callogenesis. Biosynthesized ZnO-NPs at optimum concentration showed very promising effect on plant regeneration ability. Both the explants, seeds and nodes showed dose dependent response and upon high doses exceeding 40 mg/L the results were recorded negative, whereas at 30 mg/L both explants demonstrated 70% and 76% regeneration frequency. The results conclude that ZnO-NPs enhance the plant growth and development and tailored the nutritive properties at nano-scale. Furthermore, eco-friendly approach of ZnO-NPs synthesis is strongly believed to improve in vitro regeneration frequencies in several other monocot plants.