Potencial alelopático de extratos aquosos de folhas de urucum (Bixa orellana) em Brassica oleracea var. Italica, Euphorbia heterophylla e Bidens pilosa

Abstract

Society has been gradually changing its eating habits, increasingly advocating healthy foods, and with this the cultivation of vegetables has been gaining market share by increasing its consumption. Weeds, in addition to causing a reduction in production, increase costs with the use of herbicides for their control. Food produced in na environmentally friendly and quality manner has a growing demand both nationally and worldwide. One of the alternatives of weed control in an economically viable and ecologically correct way is the use of allelopathy between plants. In view of this, the present work aims to test the allelopathic potential of aqueous extracts obtained from Bixa orellana leaves applied to broccoli seeds and in seeds of two species: Euphorbia heterophylla and Bidens pilosa. The concentrations of the extracts used were 0 (control); 10; 5; 2.5 and 1.25%, with four repetitions per treatment. The experimental design used was completely randomized. Results were obtained for Germination Speed Index (IVG), Germination Percentage (% G), Average Germination Time (TMG) and Average Germination Speed (VMG), radicle length and seedling hypocotyl and determination of matter mass dry. The data were subjected to analysis of variance at 5% probability of error in the Rbio program, and the means compared using the ScottKnott test (P≤0.05). The use of the aqueous extract of Bixa orellana leaves showed allelopathic potential for the three species tested, being negative in high concentrations of the extract, in most of the analyzed variables. The species most sensitive to the extract was the Euphorbia heterophylla. At concentrations 1.5 and 2.5%, they presented positive allelopathic potential for most variables in broccoli.