ORIGINAL ARTICLE In vitro herbicide activity of crude and fractionated leaf extracts of Blepharocalyx salicifolius (Myrtaceae) Eduardo Habermann 1 • Viviane De Cassia Pereira 2 • Maristela Imatomi 2 • Fla ´via Cevithereza Pontes 2 • Sonia Cristina Juliano Gualtieri 2 Received: 22 March 2016 / Accepted: 6 August 2016 Ó Botanical Society of Sao Paulo 2016 Abstract The excessive use of synthetic herbicides is harmful to natural and managed ecosystems. In order to solve this issue, the search for natural compounds with lower toxicity to the environment has been intensified. This study aimed (a) to evaluate the phytotoxic activity of leaf extracts of Blepharocalyx salicifolius by taking into account the elongation of wheat coleoptile as well as of the crude ethyl acetate extract on the germination and growth of two weeds; (b) to fractionate the ethyl acetate extract; and (c) to test the phytotoxicity of fractions on etiolated wheat coleoptile. Hexane, ethyl acetate, and aqueous crude extracts were obtained through extraction with organic solvents. We used the column chromatography to frac- tionate the ethyl acetate extract, which resulted in 11 ethylic acetate fractions (Fr1–Fr11). The bioassays of wheat coleoptile elongation, germination, and seedling growth of guinea grass as well as the morning glory showed that the ethyl acetate extract possessed pronounced phytotoxic potential to inhibit the elongation of wheat coleoptile at all tested concentrations. In addition to this, the extract changed the mean germination time of guinea grass seeds and inhibited the growth of shoots and roots of both weeds, the fact that caused anomalies, such as necrosis and severe atrophy. Furthermore, we identified that Fr5 and Fr6 are the most promising ethyl acetate fractions. Thus, this study presents that the ethyl acetate extract of mature leaves of B. salicifolius has potential to produce natural herbicides and that the main phytotoxins are present in the Fr5 and Fr6 fractions, thereby offering scope for further studies. Keywords Allelopathy Á Brazilian Savanna Á Ipomoea grandifolia Á Panicum maximum Á Triticum aestivum Introduction After the Green Revolution, agricultural production came to depend on a variety of synthetic herbicides to control the growth of weeds and increase the productivity of cultivated species (Dayan et al. 2009). Previous studies show that some of these products have high toxicity to the environment and low degradation rates, the facts that lead to the contamination of water resources and soils (Ritter 1990; Armas et al. 2007), and ultimately changing natural ecosystems. In cultivated ecosystems, the excessive use of these substances has resulted in the development of resistant weeds, leading to considerable economic losses (Bhowmik and Inderjit 2003; Jamil et al. 2009). Given this scenario, the research for alternative solutions, such as the use of less toxic compounds and interest in organic farming (Roseboro 2006), has intensified. The use of plant extracts in the control of weeds is widely documented in the literature, and offers some advantages, such as lower toxicity to the environment (Oliveros-Bastidas 2008), & Eduardo Habermann eduardohabermann@gmail.com 1 Grupo de Pesquisa Em Ecofisiologia de Plantas Tropicais, Laborato ´rio de Fisiologia Vegetal, Departamento de Biologia, Faculdade de Filosofia, Cie ˆncias E Letras de Ribeira ˜o Preto, Universidade de Sa ˜o Paulo, Av. Bandeirantes, 3900, Bairro Monte Alegre, CEP 14040-901 Ribeira ˜o Preto, SP, Brazil 2 Grupo de Pesquisa Em Fitoquı ´mica E Ecofisiologia de Reproduc ¸a ˜o Vegetal, Laborato ´rio de Sementes, Departamento de Bota ˆnica, Centro de Cie ˆncias Biolo ´gicas E Da Sau ´de, Universidade Federal de Sa ˜o Carlos, Via Washington Luı ´s, Km 235, CP 676, CEP 13565-905 Sa ˜o Carlos, SP, Brazil 123 Braz. J. Bot DOI 10.1007/s40415-016-0317-4