Estresse por alumínio em orégano (Origanum vulgare L.)

Abstract

Oregano is an aromatic plant used throughout human history in order to value and conserve the properties of food, being considered a natural antioxidant.Such characteristic is associated with the substances that are produced in its secondary metabolism.It is known that this process is influenced by various stress factors to which the plant is subjected.In this context, the aim of this study was to evaluate the influence of stress per aluminum in the production of oregano (Origanum vulgare L.) in hydroponic system.The work was conducted at the Agricultural Sciences Institute of UFMG, Montes Claros - MG, from September to December 2013 in NFT cultivation system with five aluminum doses in the form of AlCl3.6H2O (0, 1.25, 2.5; 3.25; 5 and 7 mg L-1 of nutrient solution), as treatments, in a completely randomized design with four replications and four plants in the useful portion.At the end of 92 days after sowing they were evaluated the yield of biomass, the free proline content, the content of total flavonoids, antioxidant activity (DPPH method) and the accumulation of nutrients in the leaves. The stress per aluminum caused reduction in biomass production of oregano, reaching reduce up to 50% plant development.There was effect of regression on free proline of the oregano content in function of aluminum doses varying from 0.48 mol g-1 (dose 0) and 0.62 mol g-1 (dose 7 mg L-1).It was adjusted a quadratic regression equation for the total flavonoid content (RE), having a negative effect of stress with the production of that metabolite.The RE values varied between 9.32 and 6.92 mg g -1 dry material.The antioxidant activity was also influenced by stress per aluminum.It was adjusted a quadratic equation for the ability to reduce DPPH (CRDPPH); values varied from 68.81% to 80.62%, with greater activity on the next dose to 3.5 mg L-1 of aluminum.The values referents to the ability of the extract to reduce DPPH in 50% (EC50) also had a quadratic equation adjusted, occurring a variation between 127.14g L-1and 83.62g L-1.The stress per aluminum caused reduction of EC50, noting a negative correlation between RE and CRDPPH and positive between RE and EC50.It stands out even that the stress per aluminum also caused the decrease in the accumulated content of all assessed nutrients.In that sense, it is concluded that the stress per aluminum caused a reduction in the biomass of oregano and interfered in the production of some secondary metabolites and in nutrient accumulation.