Evaluation of the biochar quality using the germination index / Avaliação da qualidade de biochar por meio de índice de germinação

Abstract

The objective was to evaluate, through germination tests, the quality of biochar produced from different residues. Aqueous biochar extracts were obtained from eucalyptus bark (EU), babassu nut shell (BA), pinus bark (PI), babassu bark and pinus bark (BA + PI), and mixture of Cerrado plants (CE), in addition to a control, consisting of distilled water. Seeds were sown in Petri dishes on sheets of germination paper moistened with the extracts and stored in a BOD incubator for 66 hours at 25°C and an 8-hour photoperiod. The germination percentage, radicle length, and germination index (GI) were evaluated. Values of GI were compared at the 5% level of significance by the Scott-Knott test. Values of GI for EU, BA+PI and CE were 99.3; 67.2; 58.0 and 50.0%, respectively, higher than the control. In PI, there was no significant difference. These beneficial effects of biochar are probably due to the absence, or at insignificant levels, of phytotoxic elements, the absence of salinity and the presence of nutrients in the extract. The evaluated biochar extracts showed no phytotoxicity and promoted higher germination and initial growth of lettuce, contributing to the production of more vigorous seedlings.