24-Epibrassinolídeo como mitigador no estresse oxidativo na emergência de plântulas de paricá (Schizolobium amazonicum Herb) submetidas à diferentes concentrações de arsênio.

Abstract

Paricá (Schizolobium amazonicum Huber ex Ducke) is a native species of the Amazon biome that has attractive characteristics for wood production. Arsenic is a toxic heavy metal, having as sources volcanic, seismic and anthropogenic activities, and it can enter the food chain and be bioaccumulated. The aim of the study was to evaluate whether brassinosteroid (BR) attenuates oxidative stress at emergence in paricá seedlings subjected to arsenic (As) toxicity. The experiment was carried out in the plant growth room of the Laboratory of Biodiversity Studies of Superior Plants (EBPS), Universidade Federal Rural da Amazônia (UFRA), located in Belém-Pará, from July to August 2022. A completely randomized design (DIC) was used in a 3 x 4 factorial design, with 12 treatments and 4 replications, totaling 48 experimental units containing 15 seeds per replication. The seeds were soaked for 24 hours in 3 concentrations of 24-epibrassinolide (0, 10 nM and 20 nM) and placed in sand containing different concentrations of sodium arsenite (NaAsO2 - 0, 2 mg.L-1, 4 mg.L-1, 6 mg.L-1). The data were submitted to analysis of variance using the F test (p < 0.05). The EBL positively influenced the percentage of emergence and the growth of shoots and roots, mainly at the dosage of 20nM of EBL. The increase in arsenic concentration had a negative effect. Analysis of the antioxidant system showed that the level of SOD remained constant, the production of APX and G-POD is negatively modulated by EBL in leaves. In the root, APX showed low levels and the concentration of G-POD increased with dosages of 20nM of EBL. From a global perspective, 20nM doses of EBL showed evidence of an attenuating effect.