Effect of gibberellic acid and titanium dioxide nanoparticles on growth, antioxidant defense system and mineral nutrient uptake in wheat.

Nanoparticles (NPs), as a novel source of industrial materials, have been extensively used in recent years which ultimately ends up in soils and may cause toxic effects on plants. Gibberellic acid (GA), phytohormone, has ability to minimize abiotic stresses in plants. The role of GA in minimizing titanium dioxide (TiO) NPs stress in plants is still unknown. In current study, soil was spiked with TiO NPs (0, 100, 200, 400, 600 mg/kg) while GA was foliar-sprayed at different concentrations during wheat growth. The findings revealed that TiO NPs increased the growth, chlorophyll contents, and nutrient (P, K, Fe, Mn) concentrations in tissues till 400 mg/kg and then decrease was observed at 600 mg/kg level of NPs whereas the values of these parameters were higher compared to control irrespective of NPs levels. The NPs enhanced the antioxidant activities (SOD, POD, CAT, APX) and reduced the oxidative stress (EL, HO, MDA) in leaves over the control. Foliar GA further improved the growth, yield, nutrients and antioxidant activities while minimized the oxidative stress compared to respective sole NPs- treatments. The interactive effects of NPs and GA were dose dependent. The results proved that studied doses of TiO NPs were not toxic to wheat plants except the highest level (600 mg/kg) used and GA positively affected the yield of wheat under TiO NPs application. The GA can be used to improve crop growth in the presence of NPs which, however, needs further investigation at higher doses of TiO NPs in various crops.