Evaluation of salicylic acid effect on germination and growth of Chenopodium murale L. seedling under treatment of zinc oxide (ZnO) nanoparticle

The aim of this study was to investigate the effect of salicylic acid (SA) on germination and stability of Chenopodium murale L. seedlings under treatment of zinc oxide (ZnO) nanoparticle. The nanoparticle of ZnO, as a metal nanoparticle, due to its unique properties has many applications in the production of industrial, commercial and medical products. Increased application of metal nanoparticles can lead to the entry of these particles into the food chain, which ultimately affects the health and performance of organisms. Salicylic acid (SA), as a plant growth regulator, controls some physiological processes and affects plant resistance and tolerance against biotic and abiotic stresses. In this study, sterilized seeds were pretreated for 12h with different concentrations of SA, including 0 (control), 10, 25, 50, 100 and 200 μM. Then 25 seeds were sown in petri dishes containing moistened filter-paper with 50 mg/L of ZnO nanoparticle. Due to a sharp decline in growth in higher concentrations during a preliminary study, 50 mg/L of ZnO nanoparticle was chosen as the appropriate concentration. The petri dishes were transferred into the incubator with 25 ± 2˚C. This experiment was performed in 4 replicates for each experimental treatment and some germination indices were evaluated after seven days. The results showed that with the exception of pretreatment of 10 μM SA, the other concentrations resulted in an increase in germination percentage in the seeds treated with ZnO nanoparticles. Maximum germination percentage and rate were observed in the pretreatment of 25 μM SA, other pretreatments did not show a significant difference compared to the control for germination rate. Under SA pretreatments, ZnO nanoparticle decreased seedlings length compared with the control, but it increased seedlings fresh weight. In all pretreatments of SA, ZnO nanoparticle treatment led to a significant decrease in seed vigor compared to the control. The highest level of this index was measured in 25 μM SA pretreatment. Based on these results, SA pretreatment is thought to improve the germination rate, germination percentage and fresh weight in seedlings treated with ZnO nanoparticles, but it has no significant effect on other germination indices.