Atividade alelopática de extratos de diferentes partes de juazeiro (Ziziphus joazeiro Mart. - Rhamnaceae)

Abstract

This study aimed to iden- tify the allelopathic activity of extracts from Ziziphus joazeiro bark and leaves on the seeds of lettuce (Lactuca sativa). Two experiments were conducted, which both used a randomized design. The first four replicates were the following treatments (EF-extract of leaves at 100°C, EF-extract of leaves at 25°C, EC-extract of bark at 100°C, EC-extract of bark at 25°C, and distilled water). The next five treatments used 0%, 25%, 50%, 75% and 100% concentrations of the crude extract and four replicates of 20 seeds. The crude extract was obtained after the bark and leaves were blended with water (50 g of material for 500 ml of water). The results showed that the effect of the extract depended on the concen- tration. The crude and diluted extracts did not affect germination, but in higher concentrations the extracts caused an high percentage of abnormal seedlings and the extracts of the leaves and bark produced at 100°C reduced root and shoot growth. Aqueous extracts of bark and leaves of Z. juazeiro have a toxic effect on seed germination of L. sativa.