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.

Por meio deste estudo, buscou-se identificar as ferramentas tecnológicas utilizadas no processo de ensino e aprendizagem frente à pandemia da COVID-19 em uma universidade pública do estado do Ceará. Para a coleta dados, foi realizada pesquisa exploratória com amostragem não-probabilística por conveniência, utilizando questionários semiestruturados através do Google forms.  Foram entrevistadas 126 pessoas, dos quais, 32 são professores e 96 estudantes. De acordo com as respostas dadas pelos estudantes, 86 % possuem Wi-Fi em casa. O restante utiliza internet de dados móveis ou da casa de vizinhos. Em relação às ferramentas utilizadas, 95% dos alunos utilizam Smartphones, enquanto 53% indicaram o notebook, 6% o computador e apenas 1% utiliza a TV. O Google meet foi apontado como o aplicativo mais utilizado nas aulas. Entre os professores, a maioria relatou que possuem Wi-Fi em casa e as principais ferramentas utilizadas são smartphones, notebooks, computadores e uma minoria relatou o uso de tablets. De acordo com as respostas dos professores, 73% enviam material para os alunos como forma de interação. 67% gravam as aulas e as enviam, enquanto 64% fazem videoconferência. A maior parte dos entrevistados, incluindo professores e alunos, mencionou que as aulas presenciais são mais efetivas no processo de ensino e aprendizagem.  Dessa forma, nota-se que, apesar dos esforços do corpo acadêmico para dar continuidade às atividades de ensino durante a crise de saúde, ainda é necessário muito avanço na instituição de ensino no que se refere à inserção de tecnologias nos processos educacionais.

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.

No abstract