Comparative allelopathic effects of Cryptocarya moschata and Ocotea odorifera aqueous extracts on Lactuca sativa/Efeito alelopatico comparativo de extratos aquosos de Cryptocarya moschata com Ocotea odorifera sobre Lactuca sativa

The aim of this work was to compare the allelopathic effects of aqueous leaf extracts from Cryptocarya moschata and Ocotea odorifera on the seed germination and initial growth of Lactuca sativa (lettuce). The extracts were prepared by cold maceration, which was accomplished by adding distilled water to the dried plant material 1:10 (w [v.sup.-1]) and grinding. The treatment concentrations (0, 0.25, 0.5, 0.75 and 1%) were obtained by dissolving the dried crude extract in distilled water. The allelopathic potential of the dried Ocotea odorifera and Cryptocarya moschata leaves on Lactuca sativa was observed through reduction of the percentage of seeds that germinated, the index of germination and the length of the roots as well as structural abnormalities in L. sativa seedlings. For both extracts, the extract concentration and allelopathic effect were highly correlated. However, the C. moschata extract had no effect on caulicle length at the different tested concentrations. Keywords: allelopathy, allelochemical, Lauraceae, germination. Neste trabalho foi avaliado o efeito alelopatico comparativo do extrato aquoso de folhas de Cryptocarya moschata e Ocotea odorifera sobre a germinabilidade e desenvolvimento inicial de Lactuca sativa (alface). Os extratos foram preparados por maceracao a frio, adicionando o material vegetal seco e moido a agua destilada 1:10 (m [v.sup.-1]). As concentraces tratamento de 0; 0,25; 0,5; 0,625; 0,75; 0,875 e 1% foram obtidas por meio da solubilizacao do extrato bruto seco em agua destilada. Observou-se potencial alelopatico das folhas secas de Ocotea odorifera e Cryptocarya moschata sobre Lactuca sativa pela reducao do percentual de germinacao, do indice de velocidade de germinacao e do comprimento das raizes, bem como pelas anormalidades estruturais encontradas nas plantulas. Observou-se alta correlacao entre a concentracao de extrato e efeito alelopatico com ambos os extratos. O extrato de C. moschata nao apresentou efeito sobre o comprimento do caule nas diferentes concentraces avaliadas. Palavras-chave: alelopatia, aleloquimico, Lauraceae, germinacao.