ALLELOPATHY POTENTIAL OF Mimosa tenuiflora (Willd.) Poir. AQUEOUS LEAF EXTRACT OF Lactuca sativa L. GERMINATION

This study aimed to determine the allelopathic potential of aqueous extract of leaves of jurema preta (Mimosa tenuiflora (Willd.) Poir.) on seed germination and seedling growth of lettuce. The experimental design was completely randomized with five concentrations of crude extract (0%, 25%, 50%, 75% and 100%) with four replications of 20 seeds. The pH and osmotic potential was determined for each treatment. We evaluated the germination percentage (G), germination speed index (IVG), percentage of normal seedlings (NP) and abnormal (PA), shoot (CPA) and root (CR) length in lettuce seedlings. The values of pH and osmotic potential of the extracts in the different treatments varied between 4.5 and 6.9, and 0.0 to -0.7 MPa, respectively, being within the recommended limits for the germination of lettuce seeds. The IVG did not differ significantly in different concentrations and temperatures of extraction. All extracts negatively affected growth, reducing the length of the root in more than 50% and the higher the concentration of the extracts, the lower the values of CR and CPA. The aqueous extract of leaves M. tenuifolia extract at 100 degrees C reduced the germination at higher concentrations and the extract at 25 degrees C did not affect germination. There was a negative allelopathic effect of extracts in higher concentrations in the development of seedlings of lettuce, with inhibition of root and hypocotyl/coleoptile growth, and high percentage of abnormal seedlings in the two extraction temperatures.