Co-application of indigenous arbuscular mycorrhizal fungi and nano-TiO2 reduced Cd uptake and oxidative stress in pre-flowering cowpea plants

Abstract

The symbiotic association between plant roots and arbuscular mycorrhizal fungi (AMF) promotes plant growth, and reduces toxic metals accumulation in plants. In this study, the effect of inoculation with indigenous AMF ( Glomus Spp.) and co-application of AMF and nano-TiO 2 on Cd accumulation on activities of stress enzymes in cowpea at pre-flowering stage was examined. Soil substrates were spiked with either Cd (10 mg/kg) and inoculated with either AMF suspension (7 ml) or AMF+ n TiO 2 (200 mg/kg). The results showed that inoculation with AMF and AMF+ n TiO 2 promoted germination and chlorophyll contents by at least 12% and 45%, respectively. As envisaged, AMF+ n TiO 2 reduced uptake and decreased translocation of Cd to above-ground biomass better than inoculation solely with AMF. In the aspect of Cd toxicity assessed by enzymes activity, sole AMF inoculation and AMF+ n TiO 2 had varied effects on the stress enzymes activity. However, n TiO 2 interacted synergistically with AMF to improve stress tolerance by reducing the lipid peroxidation in plants (in term of the amount of malondialdehyde) more than sole inoculation with AMF. In conclusion, the present study demonstrated that there is stimulatory effect of nano-TiO 2 on the activity of AMF in alleviating Cd stress in pre-flowering cowpea. • Combination of AMF and n TiO 2 reduced root uptake and translocation of Cd. • Synergistic interaction between AMF and n TiO 2 reduced MDA content. • Nano-TiO 2 portends stimulatory effect on AMF to reduce Cd toxicity.