Due to the increasing production and use of nanoparticles in various sectors such as electronic industries and healthcare,
concerns about the unknown effects caused by the presence of these materials in the natural environment and agricultural
systems were on the rise. Because of the growing trend of ZnO nanoparticles (nZnO) which is one of the most widely
used nanoparticles being released into the environment, it has attracted the attention for more studies to be done on
the effects of this nanoparticle on organisms. This study was carried out to investigate the phytotoxicity effect of nZnO
on groundnut seedlings in Murashige and Skoog (MS) medium. The experimental treatments of this study include eight
concentrations of nZnO (10, 30, 50, 100, 200, 400, 1000 & 2000 mg.L-1) added to MS medium and MS medium without
nanoparticles have been used as control treatment. For the first 6 days after sowing, germination percent and germination
rate index were calculated by counting the germinated seeds every day. Groundnut seedlings were incubated for 3 weeks
in optimum condition and after that, seedling characteristics such as length, wet and dry weight of radicle and plumule
were measured. The water content of radicle and plumule were also calculated. The results of this study showed that
radicle and plumule length of groundnut seedlings were affected by nZnO exposure, in a way that length of radicles in 50
mg.L-1 nZnO and higher concentrations was significantly lower than that of control treatment and the shortest plumule
length was observed in 2000 mg.L-1 nZnO concentration treatment. Both the radicle and plumule wet weight were also
decreased as the nanoparticle concentration was increased. However, despite the decreasing in radicle and plumule dry
weight with increasing in nZnO concentration, this increase was not significant. However radicle dry weight in 10 mg.L-1
nZnO was significantly higher than nZnOtreatments with 200 mg.L-1 concentration and higher concentrations. Moreover,
observations of this study did not show any significant difference between the water content of nZnO concentration
treatments and control treatment.