Efeito alelopático do extrato aquoso das folhas de Callistemon viminalis (Sol. ex Gaertn.) G.Don sobre a germinação de picão-preto (Bidens pilosa L.)

Bidens pilosa L. is a weed found in annual and perennial crops in Brazil. Due to the application of chemicals some biotypes of the species B. pilosa have shown resistance, thus recent studies have evaluated the efficiency of allelopathic substances as an alternative in the control of B. pilosa. In this context, the objective of this work was to evaluate the allelopathic effect of Callistemon viminalis leaves on black prick germination. For this, five concentrations of C. viminalis extracts were evaluated: 0% (control), 20%, 25%, 50%, 100%, in a completely randomized design with four replications. Seed quality was assessed by evaluating seed germination and daily readings were performed for fourteen days. Data were submitted to the Seedcalc package, generating final germination variables and vigor indices, which were submitted to the Shapiro-Wilk test at (p≤0.05), followed by the Scott-Knott test (p≤0.05), using the software R. The extract of C. viminalis caused negative and positive effects on germination and seed vigor indices. The concentration of 20% was stimulating and the concentrations of 25%, 50% and 100% inhibitory. Therefore, the extracts of C. viminalis showed allelopathic action in the germination of seeds of B. pilosa.