In vitro plant growth promotion by ZnO nanomaterials in indica rice seedlings (Oryza sativa L.)

This research focuses on zinc oxide nanomaterials (nano-ZnO) applied to agricultural fields. Plants were exposed to nanomaterials and responded differently in tolerance to the various concentrations and types of nanomaterials. Two cultivars (SP1 and SP90) of indica rice (Oryza sativa L.) seedlings were grown at 0-1,000 mg.L-1 nano-ZnO and their morphological and physiological response was determined. Rice seedlings were harvested 5, 7, 10 and 14 days after treatments. Results demonstrated a significant increase in biomass, growth tolerance index (GTI), chlorophyll contents and antioxidant enzyme activities of the treated plant at 100 mg.L-1 nano-ZnO but these parameters decreased with increasing nano-ZnO concentration in the treated plants at 300-1,000 mg.L-1 nano-ZnO when compared to control plants (0 mg.L-1 nano-ZnO). The high accumulations of biomass, GTI and chlorophyll contents were related to production of antioxidant enzyme activities (catalase and peroxidase) in plant cells when plants were exposed to a low dose of nano-ZnO. Further investigations will determine the effect of nano-ZnO on the plant productivity. (C) 2018 Elsevier Ltd. All rights reserved.