Potencial alelopático de extratos e frações de Neea theifera Oerst. (Nyctaginaceae) sobre sementes e plântulas de Lactuca sativa

A alelopatia é um mecanismo de interação bioquímica entre vegetais, considerada uma forma de adaptação química defensiva das plantas. Neste fenômeno, biomoléculas produzidas por uma planta são liberadas para o meio ambiente e influenciam no crescimento e desenvolvimento de plantas vizinhas. Assim, o objetivo deste trabalho foi investigar o potencial alelopático de extratos e frações de folhas de Neea theifera, por meio de bioensaios de pré e pós-emergência. Para tanto, sementes e plântulas de Lactuca sativa foram tratadas com o extrato orgânicos (nhexânico, acetato de etila e metanólico) em diferentes concentrações (5, 10 e 20 mg/mL), e frações do extrato metanólico bruto de Neea theifera, além de um grupo controle negativo (água). O teste de viabilidade nas sementes submetidas aos extratos foi realizado pelo teste do tetrazólio, já o teste de fitotoxicidade foi elucidado pela determinação do índice mitótico. Foi realizada também uma triagem fitoquímica por meio de reações específicas para detecção de possíveis classes químicas dos extratos avaliados, além de avaliar o perfil cromatográfico por meio de cromatografia de camada delgada e reveladores específicos. De acordo com a metodologia adotada e os resultados obtidos foi possível elucidar o potencial alelopático, assim como propor um mecanismo de ação dos aleloquímicos desta espécieAllelopathy is a mechanism of biochemical interaction between plants, considered a form of adaptation of plants. In this phenomenon, biomolecules are produced by a plant and are released into the environment and influence the growth and development of neighboring plants. The objective of this study was to investigate the allelopathic potential of extracts and fractions of leaves Neea thief through bioassays pre-and post-emergence. For this purpose, seeds and seedlings of Lactuca sativa were treated with organic extract (nhexânico, ethyl acetate and methanol) at different concentrations (5, 10 and 20 mg / mL), and fractions of the brute methanol extract Neea theifera, and a negative control (water). The test of viability in seeds subjected to the extracts was carried out by the tetrazolium test, already the test phytotoxicity was elucidated by determining the mitotic index. Was also carried out a phytochemical screening through specific reactions to detect possible chemical classes of extracts assessed, and to evaluate the chromatographic profile by thin layer chromatography and revealing specific. According to the methodology used and the results obtained it was possible to elucidate the allelopathic potential, and to propose a mechanism of action of allelochemicals of this speciesCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Mutagenic potential of lettuce grown from irradiated seeds

Agriculture has benefited from the use of radiation techniques, which provide plant varieties with distinguishing characteristics, such as higher productivity, precocity and greater resistance to disease, pests and harsh weather conditions. Therefore, this study aimed to analyze the mutagenicity of greenhouse-developed Lactuca sativa originated from gamma-irradiated seeds. The seeds were irradiated at doses of 25, 50, 75, 150 and 300 Gy and after done ethanol extract this seeds in three concentrations (50, 100 and 200 mg of extract/ml of water). Tests were performed based on biological assays with Allium cepa. The extracts of plants from seeds with higher levels of irradiation showed greater mitodepressive effect and number of aberrant cells may be correlated with the increase in free radicals produced by the radiation. Based on these results, we conclude that although irradiation is a useful technique in plant breeding programs, it is extremely important to evaluate the radiation dose, which guarantees the well-being of the final consumer.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Evaluation of allelopathic potential of leaf extract of kielmeyera coriacea on lactuca sativa l

Kielmeyera coriacea Mart. (Clusiaceae), popularly known as “pau-santo”, is a typical Brazilian cerrado tree known due to its varied secondary metabolites. This study aimed to determine the allelopathic potential of the hydroalcoholic extract of leaves of K. coriacea through bioassays of seed germination, seedling growth and mitotic index of Lactuca sativa L. (lettuce). In addition it was done the tetrazolium assay and a phytochemical screening. The extract concentrations caused alterations in germination parameters, in root growth and in the mitotic index. The phytochemical screening showed the presence of triterpenes, coumarins, steroids, flavonoids and condensed tannins, compounds known to confer allelopathic characteristics upon other species. These data indicate that K. coriacea presents an allelopathic potential because its leaf extracts interfere with germination and growth without any interference of pH and osmotic potential in the results.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Potencial alelopático e levantamento do banco natural de sementes sob a copa de Copaifera langsdorffii Desf

the aim of this study was to evaluate the allelopathic effect of soil samples collected under the canopies of three specimens of Copaifera langsdorffii the germination of Lactuca sativa and survey the natural seed bank according to seasonality. To test the allelopathic effect was carried experiments of pre and post-emergence with seeds of L. sativa and to quantify the stock of seeds, soil samples were collected from three specimens at three distances from the stem (1, 2 and 3 m) and at three depths (0-5, 5-10 and 10-15cm) in the region of savanna in the dry and wet seasons. The samples tested in bioassay of pre-emergence no significant influence on germinability, mean germination time and mean germination speed, but showed a difference in the synchronism of germination, these data were independent of sampling station. In test for post-emergence was observed statistical difference in the parameters evaluate (length of primary roots and hypocotyls) in both seasons. To quantify the natural seed bank were macroscopic analysis of each soil sample with the help of stereoscopic microscope. The analysis of the natural seed bank showed a larger number of seeds in the 0-5cm and in distance of 2m for both seasons. The results suggest the presence of allelochemical substances in soil samples collected under the canopy of Copaifera langsdorffii.O objetivo deste trabalho foi avaliar o efeito alelopático de amostras de solo coletadas sob a copa de três espécimes de Copaifera langsdorffii na germinação de Lactuca sativa e realizar o levantamento do banco natural de sementes de acordo com a sazonalidade. Para testar o efeito alelopático realizou-se experimentos de pré e pós-emergência com sementes de L. sativa e para quantificar o estoque de sementes, amostras de solo foram coletadas de três espécimes em três distâncias do caule (1, 2 e 3m) e em três profundidades (0-5, 5-10 e 10-15cm), na região de cerrado nas estações seca e úmida. As amostras testadas nos ensaios de pré-emergência não interferiram significativamente nos índices de germinabilidade, tempo médio e velocidade de germinação, porém demonstrou diferença no sincronismo de germinação, estes dados foram independentes da estação de coleta. No ensaio de pós-emergência foi observado diferença estatística nos parâmetros avaliados (comprimento da raiz primária e hipocótilo) em ambas estações. Para quantificação do banco natural de sementes foram feitas analises macroscópicas de cada amostra de solo com auxílio de microscópio esteroscópico. A análise do banco natural de sementes demonstrou maior número das mesmas na profundidade de 0-5cm e na distância de 2m para ambas estações. Os resultados obtidos sugerem a presença de substâncias aleloquímicas nas amostras de solo coletadas sob a copa de Copaifera langsdorffii

Phytotoxicity of extracts and fractions of Ouratea spectabilis (Mart. ex Engl.) Engl. (Ochnaceae)

Among the numerous plant species occurring in the Cerrado, Ouratea spectabilis stands out because of the lack of species that grow beneath its canopy. Therefore, this study aimed to evaluate the phytotoxic potential of different extracts and fractions of the hydroethanolic extract from leaves of O. spectabilis through laboratory bioassays of the pre-and post-emergence of seeds of Lactuca sativa L., determination of the mitotic index in root cells of Allium cepa L., antioxidant activity and phytochemical screening of different classes present in extracts and ethyl acetate fractions. It was possible to verify that different extracts and ethyl acetate fractions of O. spectabilis interfered with germination rates, as reduced germination was observed when compared with the control. Similarly, growth and development was affected in lettuce seedlings, as shown by the reduced length of primary roots and hypocotyls compared with the control. In addition, the mitotic index was reduced in treated groups compared with the negative control. HPLC-PAD analysis for both the hydroethanolic extract and its ethyl acetate fraction, showed a predominance of flavonoid compounds belonging to the groups of isoflavones and catechins in ethyl acetate fractions of hydroethanolic extracts. Thus, it was concluded that this species synthesizes phytotoxic compounds capable of interfering in the stabilization and development of other species.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Phytotoxicity of Solanum aculeatissimum Jacq: leaves extract

The objective of this study was to evaluate the phytotoxicity of Solanum aculeatissimum Jacq. leaves ethanolic extract in seeds germination, development and fixation of Lactuca sativa seedlings. The same study also aimed to assess the mitotic index of lettuce roots meristematic cells, quantification of phenols and total flavonoids and triage by mean of phytochemical testing of the main secondary metabolites classes. Bioassays of germination, development of root and hypocotyl were carried out in Petri dishes using achenes of Lactuca sativa L. cv. 'Grand Rapids' (lettuce). Concomitantly, were evaluated the physico-chemical characteristics (pH, osmotic potential and electrical conductivity), mitotic index, quantification of total phenols and flavonoids and determination of phytochemical profile of the treatments extract. The results obtained in the bioassays demonstrate that the ethanol extract of S. aculeatissimuma presents phytotoxic potential in the development of lettuce seedlings, given that the concentration of 20 mg/ml showed greater inhibition (41% of germination). The extract contains significant amounts of antioxidants, total flavonoid and phenols, where the concentration 1000µg/mL showed higher values (86.50%). Furthermore, it was possible to observe the presence of compounds with allelopathic activity in the phytochemical screening test as coumarins, tannins, terpenes, flavonoids and alkaloids. Given the above it is clear that the ethanolic extract of S. aculeatissimum presents allelopathic substances with phytotoxic activity that can affect the germination and development of other plant species in their natural environment