Considering the need to produce effective bioherbicides to control weeds and thus reduce the contamination of environments through the use of agrochemicals in control of these plants, the scientific community has been studying the allelopathic activity of several species of Caatinga, once studies indicate that some species of this biome presentind to have activity allelopathic about other plants. On this, the present study aimed to evaluate the allelopathic potential and phenolic composition of extracts of Libidibia ferrea Mart. ex Tul. on seed germination and seedling development of Calotropis procera (Aiton) WT Aiton. and Cenchrus echinatus L. For the allelopathy test, leaf, bark and root extracts, both hot (100 °C) and cold (25 °C), were used, followed by a control group (distilled H2O). Phytochemical prospecting was performed by High Performance Liquid Chromatography (HPLC). The results showed that the hot L. ferrea bark extract has allelopathic activity on C. procera and C. echinatus, which was observed in all parameters analyzed. The phytochemical results showed that L. ferrea extracts present several phenolic compounds which are possibly responsible for the results observed against the two weed species studied, with standing out Gallic acid, Catechin, Caffeic acid, Ellagic acid, and Quercetin. It is therefore necessary to isolate these compounds in view of a potential future use for L. ferrea extracts in the production of a bioherbicide.

Cereus jamacaru DC subsp. jamacaru, has been suffering from severe anthropic pressure, in addition, when their seeds are dispersed, some end up not germinating due to the action of allelochemicals. Therefore, the present study was to evaluate the allelopathic effect of the essential oil (EO) from four species over C. jamacaru germination, as well as to identify their constituents. Four plants were selected for EO extraction (Mesospherum suaveolens (L.) Kuntze, Lantana montevidensis (Spreng.) Briq., Lantana camara L., and Tarenaya spinosa (Jacq.) Raf.) and the chemical analysis was performed by GC-MS. In order to evaluate the allelopathic activity of the EO's, the C. jamacaru seeds were treated with the EO's. The results showed that the EO's presented heterogeneity in their composition, with M. suaveolens presenting the highest number of constituents (44), followed by L. camara (26), T. spinosa (23) and L. montevidensis (22). All the oils negatively affected the C. jamacaru germination percentage in a concentration-dependent manner. Regarding the GVI, the M. suaveolens, L. montevidensis and L. camara OEs significantly decreased this index at all analyzed concentrations. Based on the results obtained, it is suggested that C. jamacaru should not be sown close to the aforementioned aromatic species in reforestation programs.

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Through this study, the objective was to contribute to the knowledge regarding floristic composition, classification and conservation status of the studied plant species as well as the dispersion syndromes of flora found in a disjoint Cerrado area ​in the Chapada do Araripe, Crato-CE. For the research development Rapid Survey method, applied in three walking lines (Line 1, Line 2 and Line 3) was adopted. Floriferous branches, fruits and seeds from species in the study area were collected in order to identify them and to characterize their diaspores, in view of fitting them into the corresponding dispersion syndromes. A total of 103 species were identified, the richest species taxa were: Fabaceae, Apocynaceae, Euphorbiaceae, Malpighiaceae and Myrtaceae. The most abundant species in the studied area were: Cordiera myrciifolia (“bola”) Miconia albicans (“Candeiro-de-pelo”), Caryocar coriaceum (pequi) and Copaifera langsdorffii (“pau d'oleo”). Three new occurrences were also recorded for the state of Ceará: Eriope tumidicaulis, Myrciaria cf. tenella and Stachytapheta cf. crassifolia. The most frequent dispersion syndrome was zoochoria, followed by anemocoria. Considering that most of the species occurring in the study area have their dispersion diaspores transported by a fauna element, the importance of these species for the maintenance of the observed floristic richness is evident.

Em 1996 foi revelado à ciência o soldadinho-do-araripe (Antilophia bokermanni), pássaro endêmico da vegetação das encostas da Chapada do Araripe, no Ceará. Por sua distribuição restrita em remanescentes florestais sob pressão antrópica foi considerada Criticamente em Perigo de extinção global em 2000. Para modificar esta perspectiva, em 2003, foi iniciado um esforço contínuo de pesquisas, desenvolvimento de políticas públicas, educação ambiental e restauração florestal, visando promover a sua conservação. O foco principal deste empenho tem sido buscar a manutenção dos serviços ambientais provenientes de seu hábitat, sobretudo relacionados às águas, pois principalmente ao longo dos cursos d'água são construídos seus ninhos e concentram-se os frutos que lhe servem de alimento. Durante a execução destas ações, o Projeto Soldadinho-doararipe, estimula a participação da sociedade, beneficiária direta da conservação hídrica e florestal. Neste artigo estão os principais resultados obtidos em dez anos de atividades, tendo como objetivo inspirar outras iniciativas de conservação. Palavras-chave: Serviços ambientais. Mata Úmida. Projeto Soldadinho-do-araripe. Conservação.

The plants produce a variety of compounds that are not directly associated with their growth and are derived from their secondary metabolisms. Such compounds can be used in the formulation of bioherbicides, in the control of weeds. Among the chemical groups that most present allelopathic actions are the phenolic compounds which are present the flavonoids. A species rich in such compounds is Guapira graciliflora, which allows hypothesizing that it may present phytotoxic action. In this way, the objective of this research was to evaluate its phytotoxic action on the germination and growth of Cenchrus echinatus and Calotropis procera. For this purpose, aqueous extracts were prepared from fruits and leaves and applied to seeds of the species mentioned above. Pre and post germinative parameters were measured. Our results show that the extracts can retard the growth of the roots of C. echinatus and C. procera in a significant way (p <0.05), however it is not able to interfere in the number of germinated seeds or germinated seeds speed. The mechanisms of action of the allelochemicals may be related to inhibition of specific PSII sites or reduction of chlorophyll content. Guapira graciliflora presents allelochemicals in the constitution of its leaves and its fruits that affect the growth of the initial structures of C. echinatus and C. procera, with potential to be used as bioherbicides in the control of these weeds.

The use of cactus for forage may cause soil contamination by allelochemicals in order to compromise the future planting or even reforestation of that site. The objective of this work was to evaluate the allelopathic action of cladodes and roots of Cereus jamacaru, Pilosocereus gounellei and Tacinga inamoena on the germination and development of Cenchrus echinatus and Calotropis procera in order to suggest actions that increase efficiency in restoration strategies. Of the species of Cactaceae mentioned above, cladodes and roots were collected for the preparation of the extracts in which two types of extracts were prepared for each organ, one treatment by hot infusion and one cold treatment. Germination Percentages (GP) and Germination Speed Index (GSI) were analyzed. In order to analyze if the extracts presented some allelopathic activity regarding the development of the seedlings, the lengths of the stem and the radicle of the recipient species were measured. The results of this research show that cacti don&rsquo;t significantly affect GP from seeds of other plants. However, for GSI, roots and cladodes of T. inamoena presented negative allelopathic activity for C. echinatus and C. procera, respectively. In addition to GSI, T. inamoena negatively affected the development of C. echinatus rootlets. In this way T. inamoena is a forage cactus that affects the development of the initial structures of surrounding plants. Thus, the exacerbation of this forage species in natural areas should be avoided, since the released allelochemicals can interfere with the ecological succession of the plant species of that environment.

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