Avaliação do potencial alelopático de extratos vegetais da algaroba (Prosopis juliflora (SW) D.C.) na germinação, emergência e crescimento inicial de jurema-preta (Mimosa tenuiflora (Willd.) Poiret).

Abstract

Allelopathy is the interaction between microorganisms and/or plants by the releasing of chemicals (allelochemicals, secondary compounds and others) into the environment. This mechanism of vegetables may be one of the factors that favor the occupation of areas by invasive species and consequently reduces the native population. The objective of this study was to evaluate the allelopathic potential of different plant parts of Prosopis juliflora, invasive species, on germination, emergence and early growth of Mimosa tenuiflora, native species of Caatinga. The aqueous extracts of leaves, barks and roots from the algaroba were prepared at a ratio of 125 g of plant material to 500 ml of distilled water, diluted at concentrations of 0, 25, 50, 75 and 100%. For germination, the seeds were distributed in gerboxes lined with germitest paper moistened with the extracts. The treatments were distributed in a completely randomized design (DIC) with four replications. The percentage of germination, the germination speed index (IVG) and the average germination time (TMG) were evaluated. For emergence and early growth, tubes were used in 55 cm3, with application of the extracts every 15 days. The treatments were also distributed in DIC, with four replications and five tubes by repetition. We evaluated the percentage of emergence, plant height, stem diameter, number of leaves, dry weight of leaves, stem, root, aerial and total parts. The leaf extracts have potential allelopathic inhibitory to the germination and vigor, speed index and average time of M. tenuiflora seed germination. The root and bark extracts promote seed germination of M. tenuiflora. The root extract had no influence on the speed and the average germination time. There are allelopathic substances on the leaves of algarobas that are potentially limiting to the germination of M. tenuiflora. The leaf extracts of P. juliflora inhibit the emergence and growth of Jurema preta plants. The root extract does not influence the height and the dry weight of plants. The extracts obtained from algaroba bark do not have a negative effect on the dry weight of roots and shoots of seedlings of Jurema-preta.