Biocarvão na remediação da toxidez por alumínio e cádmio em sorghum bicolor L.

Abstract

High concentrations of heavy metals in the soil can compromise plant growth. An alternative to reduce the availability of heavy metals in the soil and to minimize their effects is the use of pyrolyzed residue, called biochar. In this study, sewage sludge biochar (BLE) and sugarcane bagasse (BBC) were characterized and tested for the ability to reduce the toxicity of aluminum and cadmium in seed germination of Sorghum bicolor L. Four experiments were conducted at the Biotechnology Laboratory of the Institute of Agrarian Sciences of the Federal University of Minas Gerais, Montes Claros-MG campus. For each of them, the completely randomized design was adopted (DIC), in factorial 5X2, being 5 doses (0; 0,5; 1; 2 and 4 mmol L-1) of the contaminant and 2 conditions (with and without the biochar), with 7 replicates. Each treatment was consisted of experimental units assembled with Petri plates (10 cm) in diameter, containing germitest paper, 5 ml of the metal solution and 10 seeds of sorghum. The Petri plates were closed with plastic film and kept in the germination chamber type B.O.D with temperature of 25±1ºC, in the absence of light for 10 days. On the fourth day, the evaluations were carried out: germination speed, percentage of germination and normal seedlings. On the tenth day, the lengths and dry masses of roots and shoot were evaluated. The characterization of the biochars indicated higher values of pH and CTC for BLE, favorable conditions for the retention of aluminum and cadmium in the culture medium. The biocharcoal had no effect on the speed and percentage of germination of the seeds in the presence of metals, however, the Al presented higher toxicity to the seedlings. The addition of biochar, in the culture media, provided greater survival and growth of sorghum seedlings, although the BLE was more efficient in the metals remediation process.