Allelopathic effect of anacardium humile mart. In the germination and growth of Lactuca Sativa l. and Raphanus Sativus l.

Resumo

In this research it was evaluated the allelopathic potential of aqueous extracts from Anacardium humile stems and leaves in seed germination and seedling growth of radish and lettuce. In the germination tests the aqueous extracts were used at 0, 4, 8, 12 and 16% (w/v) concentration. Four replicates of thirty seeds of lettuce and radish were distributed in Petri dishes covered with filter paper moistened with 5 mL different extracts, kept at 27 ^oC and light absence. The counting of germinated seeds was performed daily, being calculated speed and the percentage of germination. In tests measuring the germination percentage, only radish`s seeds were affected by the aqueous extracts of leaves 8%. The speed’s germination in lettuce seeds was significantly reduced using leaves extract at all concentrations. Leaf extracts 8, 12, 16% and stems extracts 8% also caused significant reductions in the speed germination of radish seeds. Growth experiments were carried out with four replicates of eight germinated seeds of lettuce and radish, at 27 ^oC, ten days after the germination and having filter paper as substratum, moistened with 0%, 4% and 12% of aqueous extracts. Both, lettuce and radish, presented a significant inhibition of total length when stem extracts were used. Leaves’s extracts 4% and 12% also produced significant growth inhibition in radish seedlings. The extracts interference on seed germination and seedling growth of lettuce and radish was disassociated of pH and osmotic potential influence, indicating an allelopathic potential of the species studied.