Potencial fitotóxico e citogenotóxico de folhas e epicarpos de diferentes Cultivares de Coffea arabica L. em bioensaio vegetal.

Abstract

In order to discover new bioherbicidal substances, it is proposed, in the present work, to study the viability of the use of coffee leaves and pericarp (C. arabica L.) as a source of allelochemicals, evaluating the phytotoxic and cytogenotoxic action of extracts Acaiá, Yellow Bourbon, Catuaí Amarelo and Topázio in bioassay with Lactuca sativa L. The extracts were prepared at concentrations of 5, 10, 20 e 40 mg.mL-1, and were characterized for pH and osmolarity. As control the distilled water (0%) was used. The phytotoxic tests were performed in blocks completely randomized. Those of cytotoxicity were in a completely randomized design, with 8 treatments and 3 replicates. The enzymatic activity and the lipid peroxidation were analy zed. The results were submitted to ANOVA and the means comparison was done by the Scott Knott test (p ≤ 0.05). The parameters evaluated were: initial and final germination percentage, germination rate index, allelopathic effect index, shoot length, root length, mitotic index and frequency of chromosomal abnormalities. Leaf extracts and pericarp of different cultivars of C. arabica at higher concentrations were found to reduce the parameters evaluated. The mitotic index was reduced in comparison to the control and the frequency of abnormalities was smaller. Abnormalities such as micronuclei, anaphase and telophase bridges, c-metaphases, stickiness, lost chromosomes, delayed anaphase chromosome and telophase were observed. The gradual increase of the extract concentration of different leaf and pericarp cultivars of C. arabica affects the germination performance of L. sativa seeds, besides causing changes in the enzymatic activity and cell division.