237 JCHR (2022) 12(2), 237-246 Journal of Chemical Health Risks www.jchr.org ORIGINAL ARTICLE Investigation of Seed Germination, Early Growth and Physio- Biochemical Parameters of Canola Seedling Exposed to Co 3 O 4 Engineered Nanoparticles Malihe Jahani *1 , Ramazan Ali Khavari-Nejad 1 , Homa Mahmoodzadeh 2 , Sara Saadatmand 1 1 Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran 2 Department of Biology, Mashhad Branch, Islamic Azad University, Mashhad, Iran (Received: 18 January 2020 Accepted: 19 December 2020) KEYWORDS Antioxidant capacity; Canola seedling; Nano-sized cobalt oxide; Oxidative stress; Plumule and radicle growth; Seed germination ABSTRACT: 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 Co 3 O 4 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 Co 3 O 4 (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 Co 3 O 4 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 H 2 O 2 content raised at higher dosages of nano- sized Co 3 O 4 . The activity of antioxidant enzymes were enhanced by nano-sized Co 3 O 4 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 Co 3 O 4 but decremented at higher dosages. The content of malondialdehyde and lipoxygenase activity heightened after 0.1 g L -1 of nano-sized Co 3 O 4 . Altogether, the results confirmed the inducive oxidative stress of nano- sized Co 3 O 4 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. INTRODUCTION Nanotechnology is at the front line of science and innovation, which has been progressing rapidly and has meaningful utilizations in human life [1-5]. The expanding utilization of NPs can prompt their delivery into the climate and their impacts on biological system [6]. The infiltration of NPs into the cell wall of plants may lead to destructive influence and alternation in the genetic and morpho- physiological properties of plants. The reaction of plants to NPs according to the plant species type and their development stages, and additionally the NPs nature is dissimilar [8]. Cobalt (Co) is a magnetic element with similar properties to nickel and iron [9]. Co can be a pollutant in soils because of agricultural additives or metal refineries [10]. In plants, Co has a crucial role in several processes such as photosynthesis, respiration, and cell growth [11]. Two salts * Corresponding author: malihe.jahani63@gmail.com (M.Jahani) DOI: 10.22034/jchr.2020.1891185.1092