Acta Biologica Cracoviensia s. Botanica

Abstract

Nanotechnology has been widely applied in agriculture, and understanding of the mechanisms of plant interaction with nanoparticles (NPs) as environmental contaminants is important. The aim of this study was to determine the effects of foliar application of cobalt oxide (Co 3 O 4 ) NPs on some morpho-physiological and biochemical changes of canola (Brassica napus L.) leaves. Seeds were sown in plastic pots and grown under controlled conditions. Fourteen-day-old seedlings were sprayed with different concentrations of Co 3 O 4 NPs (0, 50, 100, 250, 500, 1000, 2000, and 4000 mg L -1 ) at weekly intervals for 5 weeks. Growth parameters of the shoot (length, fresh and dry weights) were stimulated by low concentrations of Co 3 O 4 NPs (50 and 100 mg L -1 ) and repressed by higher concentrations. Similar trends were observed in photosynthetic pigment contents. The results indicated that high concentrations of Co 3 O 4 NPs increased lipoxygenase (LOX) activity and the malondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), and dehydroascorbate (DHA) contents, but reduced the membrane stability index (MSI), ascorbate (ASC), and glutathione (GSH). Despite the increase of antioxidant capacity (DPPH) and the accumulation of nonenzymatic antioxidants (total flavonoids and flavonols) and osmolytes (proline, glycine betaine (GB) and soluble sugars) at high concentrations of Co 3 O 4 NPs, the growth and photosynthesis were reduced. The defence system activity did not seem to be sufficient to detoxify reactive oxygen species (ROS). Altogether, high concentrations of Co 3 O 4 NPs showed a phytotoxic potential for canola as an oilseed crop.