Investigation of Seed Germination, Early Growth and Physio-Biochemical Parameters of Canola Seedling Exposed to Co3O4 Engineered Nanoparticles

The incessant use of nanoparticles (NPs) may pose serious threats on ecosystem and plants are at maximum risk of their delivery into the environment. The goal of this research was to explore the influence of nano-sized Co3O4 on seed germination, early growth and physio-biochemical parameters of 6-day-old seedling of canola. Seeds were sprouted in Petri plates involving eight various dosages of nano-sized Co3O4 (0-4 g L^-1) for 6 days. Germination and early growth parameters (fresh and dry weights of seedling and lengths of radicle and seedling) stimulated at 0.05 and/or 0.1 g L^-1 of nano-sized Co3O4 but retarded after 0.1 g L^-1 NPs. However, the length of plumule retarded after 0.25 g L^-1 NPs. The antioxidant capacity and H2O2 content raised at higher dosages of nano-sized Co3O4. The activity of antioxidant enzymes were enhanced by nano-sized Co3O4 treatment but were repressed at higher dosages. The activity of phenylalanine ammonialyase and phenol content incremented at 0.5 and 1 g L^-1 of nano-sized Co3O4 but decremented at higher dosages. The content of malondialdehyde and lipoxygenase activity heightened after 0.1 g L^-1 of nano-sized Co3O4. Altogether, the results confirmed the inducive oxidative stress of nano-sized Co3O4 that was accompanied by plant defense system including enzymes, phenolic compounds and compatible osmolytes such as proline. However, high dosages of the NPs caused toxic impacts on physio-biochemical traits of canola seedling as an oilseed crop.