Lindamir Hernandez Pastorini

Interferência alelopática de Raphanus raphanistrum L. sobre a germinação de Lactuca sativa L. e Solanum lycopersicon L.

This article aims at verifying the possible allelopathic effects of Raphanus raphanistrum L. on the germination of lettuce and tomato seeds. For that, we prepare aqueous extracts of nabica leaves and roots. After the leaves and roots were triturated in industrial blender, we diluted the raw extract in distilled water, until the concentrations of five and ten percent (m/v). The germination tests were accomplished by putting twenty-five lettuce and tomato seeds in Petri plates, which were humidified with the obtained extracts, accomplishing four repetitions in each treatment. The control treatment was only watered with distilled water. The seeds were kept in germination camera at twenty-five degrees Celsius for five days. After that period, we observed that all the concentrations of nabica extract reduced the percentage, speed, index of germination speed and radicular length of lettuce seeds, being larger the effect in the treatments with leaves. In tomato seeds, only the ten-percent extract of leaves reduced the germination percentage, radicular and epicotyl length. However, ten-percent extracts of leaves and roots caused delay in the germination process and number of plantules germinated a day, being the ten-percent extract of leaves more active.

Atividade alelopática de folhas e pseudofrutos de Hovenia dulcis Thunb. (Rhamnaceae) sobre a germinação de Lactuca sativa L. (Asteraceae)

Neste trabalho, objetivou-se avaliar o efeito alelopatico de folhas secas e pseudofrutos de Hovenia dulcis Thunb. sobre sementes de alface. Para isso, prepararam-se extratos aquosos de folhas e pseudofrutos nas concentracoes 1, 2 e 4% (m/v). Realizou-se quatro repeticoes de 25 sementes de alface, distribuidas em placas de Petri forradas com papel Germitest e umedecidas com os extratos, mantidas em câmara de germinacao a temperatura de 25°C, fotoperiodo constante e presenca de luz por cinco dias, sendo o controle agua destilada. Calculou-se a porcentagem, a velocidade, o indice de velocidade de germinacao, o comprimento radicular e da parte aerea das plântulas, bem como o efeito das sementes na presenca de diferentes solucoes de pH. Observou-se que as plântulas foram significativamente afetadas na presenca de extratos aquosos de folhas secas e pseudofrutos nas concentracoes 2 e 4%. Os efeitos foram desvinculados do pH e potencial osmotico, indicando, portanto, interferencia alelopatica dos extratos obtidos de Hovenia dulcis.

Efeito alelopático de frutos de umbu (Phytolacca dioica L.) sobre a germinação e crescimento inicial de alface e picão-preto

As plantas produzem substâncias por meio do metabolismo secundario. Quando liberadas no meio ambiente sao capazes de interferir na germinacao e no desenvolvimento de outras plantas. Objetivou-se, nesta pesquisa investigar os efeitos alelopaticos de umbu (Phytolacca dioica L.) sobre a germinacao e o crescimento inicial de alface e picao-preto, em laboratorio, utilizando-se extratos aquosos de frutos de umbu nas concentracoes 0, 1, 2, 4 e 8%; foi realizada analise fitoquimica dos frutos e testes de pH e potencial osmotico dos extratos de frutos. Analisaram-se, para a germinacao os parâmetros: porcentagem de germinacao (PG), velocidade de germinacao (VG) e indice de velocidade de germinacao (IVG); para o crescimento inicial analisaram-se os parâmetros: comprimento (radicular e da parte aerea) e biomassa (fresca e seca) das plântulas de alface e picao-preto. Os dados foram submetidos ao teste de Tukey, a 1% de probabilidade. Os parâmetros PG, VG e IVG foram alterados significativamente, proporcionais ao aumento da concentracao dos extratos de frutos do umbu. O comprimento (radicular e da parte aerea) e a biomassa (fresca e seca) das plântulas de alface e picao-preto foram reduzidos significativamente com o aumento da concentracao dos extratos aquosos de frutos de umbu. O pH e potencial osmotico dos extratos mantiveram-se dentro de padroes adequados e a analise fitoquimica revelou a presenca de flavonoides. Pelos resultados os frutos de umbu apresentaram-se com efeito alelopatico sobre a alface e o picao-preto.

Comunidade de fungos Agaricomycetes em diferentes sistemas florestais no noroeste do Estado do Rio Grande do Sul, Brasil: Floresta Estacional Decídua e monocultura de eucalipto

Agaricomycetes fungi community at different forest systems in the northwest of Rio Grande do Sul State, Brazil: seasonal deciduous forest and eucalypt monoculture). Monocultures differ from native forests in relation to plant heterogeneity, variety of substrates, and soil humidity, possibly altering the diversity of organisms, such as the fungi. This study aimed to compare the richness, abundance, and composition of Agaricomycetes fungi in a native forest and in a eucalypt monoculture. The fungi were collected in a seasonal deciduous forest area and in a Eucalyptus grandis monoculture, in the northwest of Rio Grande do Sul State, Brazil. The abundance and richness of fungi were significantly lower in the eucalypt plantation than in the native forest and the species composition differed between the areas. Thus, it was concluded that the eucalypt monoculture negatively affects the Agaricomycetes fungi community.

Germination responses of four pioneer plant species after passage through the gut of a frugivorous Neotropical bat

ABSTRACT Seed passage through the guts of bats potentially influences germination in different ways: physically, chemically and biologically. To evaluate the influence of a Neotropical bat on the seed germination of four pioneer plant species, an experiment was conducted. Considering the positive influence of bats on germination and the possibility of observing non-viability caused by microorganisms, we hypothesized that (i) seeds subjected to passage through bat guts without the influence of microorganisms have a higher germination potential. Considering the different ecological requirements for the germination of plant species, we also hypothesized that (ii) the four plant species present different germination parameters. The germination of seeds from feces and fruits in the presence and absence of microorganisms was compared for each plant species and among the four plant species. The ingestion of seeds by bats and the presence of microorganisms either improved or did not influence the germination parameters of plants, but the direction of the effects did not support the hypothesis in all cases. The germination parameters differed among most plant species except between Ficus adhatodifolia and F. guaranitica. Our findings indicate that the influence of bats on seeds depends on the microorganisms and singularities of plant species.

Digestion time and intactness of seeds ingested by Sturnira lilium (E. Geoffroy, 1810) (Mammalia, Chiroptera)

ABSTRACT Bats are responsible for many ecological services, such as seed dispersal of several plant species, contributing to the processes of succession and forest regeneration. A factor that can interfere with this process is the animal digestion, which can affect germination, altering the patterns of seedling distribution. The effects of seed passage through bats’ guts varies with the species, leading to some discrepancies in the literature. In this study, we tested the digestion time of one Phyllostomidae bat species, Sturnira lilium, in two Neotropical plants: Solanum paniculatum and Ficus organensis, and the effects on seed germination. The experiment was conducted in captivity and the germination tests were made in laboratory conditions. The results suggested that most seeds ingested by S. lilium are dispersed within 40 min for both species and the digestion seems not to significantly affect the germination of F. organensis, despite the slight acceleration of germination. In S. paniculatum, germination occurred only in the control (39%), whereas in the treatments, all the seeds remained dormant during the 25 experimental days. In this case, the digestion of S. lilium possibly contributes to the formation of seed banks, randomizing the temporal distribution of seedlings.