P-350 - Elemental composition and antioxidant enzyme activity of roots and shoots of wheat grown in manganese spiked Montado alentejano soil

Abstract

Soils occupied by the Montado system are acid and susceptible to winter waterlogging, promoting soil Mn bioavailability and its plant toxicity, that impairs crop yields. Plant Mg/Mn ratios >20 and increased plant antioxidant enzyme activity may reduce Mn toxicity. The aims of this work are the evaluation of a) the bioavailability of soil Mg and Mn, b) wheat shoot and root Mg and Mn concentrations and c) the antioxidant enzyme activity of wheat grown in soil spiked with Mn. Soil elements were evaluated through XRF and extractable elements through AAS. Wheat was grown for 3 weeks in soil spiked with 0, 45.2 and 90.4 mg MnCl2/kg soil. Shoot and root Mg and Mn were quantified through ICP-MS and enzyme activity through UV/Vis-spectrophotometry. Soil pH was 5.6 with an extractable Mg/Mn of 4. Mn, in spiked soil, was readily assimilated and promoted a decrease in Mg plant uptake, due to a decrease in soil Mg/Mn ratio. Increasing Mn concentrations decreased superoxide dismutase activity in roots but not in shoots. Catalase activity increased at 45.2 mg Mn/Kg but decreased at the highest Mn concentration. Mn bioavailability, under waterlogging, seems to impact wheat antioxidant enzyme activity. Ongoing work will determine subcellular Mn distribution and other antioxidant enzymes activity.