International Journal of Environmental & Agriculture Research (IJOEAR) ISSN:[2454-1850] [Vol-2, Issue-10, October- 2016] Page | 124 Allelochemicals of Neea theifera Oerst. (Nyctaginaceae) with phytotoxic potential on plant germination and growth Valter Henrique Marinho dos Santos 1 , Gustavo Franciscatti Mecina 2 , Paulo César Ferreira 3 , Anne Lígia Dokkedal 4 , Luiz Leonado Saldanha 5 , Gisele Pigatto 6 , Luciana Pereira Silva 7 , Regildo Márcio Gonçalves da Silva 8 1 Universidade Estadual Paulista (UNESP), Instituto de Biociências de Botucatu, Departamento de Química e Bioquímica, Botucatu, SP, Brasil 2,3,6,8 Universidade Estadual Paulista (UNESP), Faculdade de Ciências e Letras de Assis, Departamento de Biotecnologia, Laboratório de Fitoterápicos, Assis, SP, Brasil 4,5 Universidade Estadual Paulista (UNESP), Departamento de Ciências Biológicas, Bauru, SP, Brasil. 7 Fundação Educacional do Município de Assis (FEMA), Assis, SP, Brasil. Abstract— Plant species able to produce phytotoxic substances are widely studied in agronomy because when identified and isolated can lead to herbicides or insecticides less toxic than current pesticides. Knowing the ecological characteristics of the Neea theifera species in cerrado biome, this study aimed to evaluate the phytotoxic effect of extracts and fractions of leaves and screen the secondary compounds in the methanol extract. The organic extracts and fractions showed phytotoxic potential in germination indexes, the initial growth of the root system and the mitotic index of L. sativa. In phytochemical screening performed by HPLC-PAD was possible to identify the presence of phenolic compounds, mainly flavonoids, a secondary class of compounds widely known in the literature for its medicinal and allelopathic actions. Therefore, according to the results it can be concluded that the species N. theifera is capable of producing phytotoxic compounds, since the leaf extracts and fractions changed the pattern germination indexes, root length and mitotic index of lettuce. Keywords— germination indexes, HPLC-PAD, mitotic index, Phytotoxicity, Root length. I. INTRODUCTION The agricultural pest management occurs primarily through the use of chemical pesticides, which are often inadequate causing environmental damage. This situation may change physical and chemical properties of soil and water. However, it is common knowledge the importance of synthetic products for increased food production (Tigre et al. 2012). Given this reality, alternative methods of weed and pests control are required. With several professionals from different areas investigating different alternatives, it is possible to assure that the plant phytotoxic compounds can be highlighted as a good solution for the problem (Rice 1984; Inderjit et al. 2011). Some plant species have the ability to produce chemical compounds which, when released into the environment, may interfere directly or indirectly with the growth and development of other nearby organisms. Such phytotoxic phenomenon is known as allelopathy (Inderjit and Duke 2003; Silva et al. 2012). The allelochemicals indirect effects include changes in properties and nutritional soil characteristics, also changing the activity and different population dynamics. It is already known that the direct effects can cause alterations in growth and plant metabolism, involving changes at the cellular level, phytohormonal, photosynthetic, respiratory, protein synthesis, lipid metabolism and organic acids; inhibition or stimulation of specific enzymatic activity, effects on water relationship and on DNA or RNA the synthesis in target plants (Rizvi et al. 1992; Inderjit et al. 2011). In the brazilian savanna, allelopathy is responsible for interspecific and intraspecific interactions in stabilization and maintenance of different life forms present in this biome (Durigan et al. 2004). Among numerous plants species occurring in this biome, Neea theifera (Nyctaginaceae) stands out by popular accounts, having a peculiar ecological characteristic: beneath its canopy does not occur the development of other plant species. Neea theifera, popularly known as "field-pink- cover" belongs to Nyctaginacea family. It occurs in grassland phytophysiogenomies in the east and north of the São Paulo state, Brazil (Furlan 1996). It is classified as a small tree with rough branches, simple leaves, flowers arranged in panicles and reddish yellow oblong fruits (Durigan et al. 2004). In addition to their ecological traits, the species is also used in popular medicine to treat stomach ulcers and