Entomofauna visitante de Belamcanda chinensis (L.) DC (Iridaceae) durante o período de floração

A study of the reproductive biology of B. chinensis (L.) DC. (Iridaceae) was realized comprising floral biology and breeding systems. The floral biology studies included analyses of nectar production, occurence of osmophores, corolla pigments, ultraviolet reflexion and absortion patterns, viability of pollen, pollinators and flower visitors. The breeding systems were studied taking into account the results of manual pollinators tests. B. chinensis is self-compatible bul cross-pollination is more frequent. The effective pollinators are Plebeia droryana (Friese, 1906) (45,7%), Trigona spinipes (Fabricius, 1793) (27,3%), Tetragonisca angustula (Latreille, 1811) (9,3%). Others insects visitors are considered nectar and pollen thieves. The flowering begins generally in January and February. The complete reproductive cicle, as here considered, begining with floral bud production ending with development of mature fruits, lasts January to June. Seed dispersion is ornitocoric.

Germination of Styrax camporum Pohl. seeds in response to substrate types, moisture contents and the seed morphology

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Influence of culture media in viability test of conidia of entomopathogenic fungi

O presente trabalho objetivou investigar se meios de cultura utilizados em teste de viabilidade afetam a germinação de conídios de cinco isolados de Lecanicillium lecanii, cinco de Beauveria bassiana e quatro de Paecilomyces fumosoroseus. Os testes foram realizados em lâminas de microscopia contendo um dos seguintes meios de cultura: Ágar-água (AA), Meio Mínimo (MM), Batata, dextrose e ágar (BDA), Batata, dextrose, ágar e 1% de extrato de levedura (BDAL), Sabouraud, dextrose, ágar e extrato de levedura (SDAL) e Meio Completo (MC). Delimitaram-se três áreas por lâmina e em cada uma aplicou-se 0,05mL de uma suspensão com concentração de 5,5 x 105 conídios ml-1. Para cada isolado foi realizado um bioensaio, com seis tratamentos e cinco repetições. Avaliou-se a germinação 15 horas após incubação, a 26±0,5ºC. Os meios de cultura influíram na capacidade de germinação das três espécies estudadas, ocorrendo variações inter e intraespecíficas. Verificou-se que os meios Completo e BDA proporcionaram as maiores porcentagens de germinação dos isolados de L. lecanii, sendo que e as menores foram obtidas nos meios SDAL e AA. Os meios ricos em nutrientes (BDA, BDAL e Completo) favoreceram a germinação dos isolados de B. bassiana, o que não ocorreu com os meios pobres (AA e MM). Nos meios Completo e BDA foram obtidas as maiores porcentagens de germinação dos isolados de P. fumosoroseus. As menores percentagens, por sua vez, foram obtidas no meio SDAL. Entretanto, alguns isolados apresentaram alta germinação em meios pobres em nutrientes (AA e MM).

Estudo da embebição e da viabilidade de sementes de macadâmia (Macadamia integrifolia Maiden & Betche)

O presente trabalho teve como objetivo, verificar o tempo de armazenamento necessário para que seja atingida a viabilidade máxima e o tempo de embebição máxima de sementes de macadâmia (Macadamia integrifolia Maiden & Betche var. IAC-4-20). As sementes foram pesadas e colocadas em recipientes com água para que ocorresse o processo da embebição, sendo realizada a pesagem a cada 6 horas. Pode-se concluir que a embebição foi máxima ao redor de 90 horas após o início da embebição. Para a análise da viabilidade das sementes, estas foram semeadas mensalmente, durante 12 meses a partir da colheita. Verificou-se que a viabilidade máxima das sementes é atingida, 4 meses após o início do armazenamento.

Limit between stages I and II of a seed imbibition curve

O conhecimento das fases de absorção de água das diferentes espécies é importante em pesquisas objetivando melhorar a qualidade das sementes, utilizando tratamentos como condicionamento osmótico, pré-hidratação e uso de bioreguladores. O objetivo do presente trabalho foi estabelecer uma metodologia para determinar o limite entre a primeira e a segunda fase do processo, considerando o modelo W = f(t) - (a - w0)exp(-kt), utilizando testes estatísticos. O limite entre as duas primeiras fases do processo de absorção de água pelas sementes, foi determinado utilizando-se a distribuição assintótica de uma função de estimadores. O ponto a partir do qual esta diferença (W*) deixa de ser significativa foi determinado utilizando-se o teste estatístico T de Student. Para os dados utilizados como exemplo, tem-se o modelo ou =(0,434 + 0,00162 t) - (0,434 - w o)exp(-0,121 t), com r² = 0,98 e W* = (0,434 - w o) exp(-0,121 t). O valor de t encontrado (27,2 horas) é menor do que o valor determinado, considerando-se como critério para mudança de fase a diferença de 1% entre a assíntota e o valor estimado pelo modelo ajustado. Essa diferença de duas horas corresponde a 0,28% de água absorvida.

Seed weight of Xylopia aromatica (Annonaceae): quality evaluation from X-ray and seedling emergence

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chemical treatment of post-harvest Marandu grass seed residues with different moisture contents

Objetivou-se avaliar o efeito do tratamento químico com ureia (3 ou 5% na MS) e amônia anidra (3% na MS) no feno de resíduo pós-colheita de sementes de Brachiaria brizantha, cv. Marandu, contendo diferentes teores de umidade (15, 25 ou 30%). O delineamento experimental foi em blocos ao acaso com oito tratamentos e quatro repetições (camadas de fardos dentro das pilhas). O feno tratado com 3% de amônia anidra com 15% de umidade ocasionou redução de 84,3 para 79,1% nos teores de fibra em detergente neutro (FDN) e elevação de 37,3 para 55,5% na digestibilidade in vitro da matéria seca (MS) em relação ao grupo controle. A variação na umidade não alterou de maneira significativa a ação da amônia, cujos valores médios foram 77,6% de FDN e 57,3% de digestibilidade in vitro da MS. O feno com 5% de ureia reduziu os teores de FDN de 84,3 para 79,6% em relação ao feno não-tratado, o que tornou necessário o aumento da umidade para 30% para maior efeito sobre a digestibilidade da MS, que aumentou 12 unidades percentuais.

PHYTOCHROME CONTROLLED SEED-GERMINATION IN LIGHT INSENSITIVE SEEDS OF RAPHANUS-SATIVUS L CV REDONDO GIGANTE

Seed germination of Raphanus sativus is inhibited by light only under low water potential of the medium. Curves of fluence response to white, red and far-red lights demonstrated that the inhibition of seed germination is dependent on light irradiance being far-red light the more effective than the formers and the germination being inhibited by intermitent light indicates phytochrome involvement through the high irradiance reactions in the control of seed germination in radish seeds under water stress conditions.

Effects of microhabitat on palm seed predation in two forest fragments in southeast Brazil

The establishment of plants depends crucially on where seeds are deposited in the environment. Some authors suggest that in forest understory seed predation is lower than in gaps, and higher than at the forest edge. However, most studies have been carried out in large forest patches and very little is known about the effects of microhabitat conditions on seed predation in forest fragments. We evaluated the effects of three microhabitats (gaps, forest edge, and understory) on seed predation of two palm species (Euterpe edulis and Syagrus romanzoffiana) in two semi-deciduous forest fragments (230 and 2100 hat in southeast Brazil. Our objective was to test two hypotheses: (1) Low rodent abundance in small fragments as a result of meso-predator action levels leads to lower seed predation in small fragments. (2) Most mammal species in small fragments are generalists with respect to diet and habitat, so that seed predation is similar in different microhabitats (gaps, forest edge and understory) in the small fragment, but not in the larger one. The study community of small fragments is usually composed of generalist species (in diet and habitat aspects), so we expected the same rate of seed predation among microhabitats (gaps, forest edge and understory) in the tested smaller fragment. The experiment was carried out in the dry season (for E. edulis) and in the wet season (for S. romanzoffiana) in 1999. We conclude that post-dispersal seed predation in forest fragments can be directly connected with mammal communities, reflecting their historical and ecological aspects. (C) 2004 Elsevier SAS. All rights reserved.

Effects of maturation and scarification on seed germination of Syagrus schizophylla (Mart.) glass. (Arecaceae)

Syagrus schizophylla (Mart.) Glass. belongs to the Arecaccae family. This palm is native of Brazil and presents great potential for use in gardens and cultivation in pot. Palms species, with relatively few exceptions, can only be propagated from seeds; even so, there are no reports in the literature about the germination of this palm seeds. The seed maturity is a factor that interferes in the success of the germination process. For some species, studies showed that palm seeds germinated better when the fruits were completely ripe (showing full color) and for other, when they were with green coloration. Several species of the Arecaccae family presents physical dormancy of seeds in varied degrees, demanding treatments for improve germination. The objective of this work was to study the effects of maturation and of the scarification on seed germination of S. schizophylla. The experimental design used was a factorial 3 x 2 (3 maturation stadiums: green, half-ripe - yellow and completely ripe - red; and mechanical scarification: with and without), entirely casualized, with four replications of 15 seeds per plot. The seeds (with 32,43% of humidity) were placed in plastic boxes with sand (60% of humidity, placing water according to weight in each three days), under controlled conditions of alternated temperature of 25-35 degrees C, photoperiod of 12 hours. The percentage of germination and the speed germination index (SGI) were evaluated until 79 days. It was observed that, so much for germination percentage as for SGI, there was not significant difference for the interaction among the two factors, maturation stadium and scarification, however, there were significant differences among the maturation stadiums and between seeds scarified or not. The seeds from green fruits presented lower germination percentage and slower germination when compared with seeds from yellow or red fruits; the seeds from yellow or red fruits didn't differ statistically to each other. To seeds scarificated, independently of the maturation stadium, presented germination percentage significantly larger and the germination was significantly faster when compared with the seeds without scarification.

Criteria for peanut seed pre-conditioning for the tetrazolium test

The staining pattern of peanut (Arachis hypogaea L.) seeds with a tetrazolium solution was evaluated to determine the adequate conditions of seed quality evaluations. Three seed lots with different vigour levels and similar moisture content were pre-conditioned using the combination of five periods of time (4, 8, 12, 16 and 20 hours) and four temperatures (20, 25, 30 and 35 degrees C) and then exposed to a 1.0% tetrazolium solution for three hours. The moisture content levels of seeds conditioned for 8 hours at the temperatures of 25, 30 or 35 degrees C, for 12 hours at 20 or 25 degrees C and for 16 hours at 20 degrees C, were above 30%. In this range of moisture level, the staining in tetrazolium was clear and uniform, reflecting an appropriate conditioning of the seeds. However, under a practical point of view, the period of 16 hours at 20 degrees C showed to be the best option, since it allows to start the pre-conditioning an late afternoon of one day and submit the seeds for staining in the following morning.

Pollen viability in Syagrus romanzoffiana and S-coronata (Arecaceae)

Palms of the Syagrus genus have several natural hybrids in Brazil. They are widely cultivated around the world as ornamental palm. S. romanzoffiana is the parental of natural hybrids with other Syagrus species that are potentially useful as palm cultivated for heart of palm production. The objective of this work was to evaluate the pollen grains viability got from plants grown in the Experimental Nursery of the FCAVJ/UNESP, Jaboticabal, SP, Brazil. Pollen grains were sampled from inflorescence in three occasions: in the right day of anthesis, one day before and one day after anthesis. For each day, the inflorescence was subdivided in epical, medium and basal portions where pollen grains were collected. The results shown that: a) for S. coronata there was no statistical differences in pollen viability (pollen viability average = 92.89%); b) for S. romanzoffiana the average pollen viability was 87.27%, 87.47% e 86.85% before, during and after the anthesis, respectively. The basal portion pollen grains had lower viability (85.19% - p<0.01) than those from the medium (88.17%) and the apical (88.46%) portion of the inflorescence. These results shown that both species have no problems with pollen viability and can be used as parental of hybrids with other Syagrus species.

Evidence of hetero-epitaxial growth of Pb(Mg1/3Nb2/3)O-3 on the BaTiO3 seed particles of a citrate solution

Citrate solution was employed in preparing Pb(Mg1/3Nb1/3)O-3 (PMN) powder from polymeric precursors. BaTiO3 particles of 600 nm average size were used as seed for growing PMN. X-ray diffraction (XRD) indicated the presence of both, pyrochlore Pb6Nb6MgO22 (P6N) and perovskite phases. Transmission electron microscopy (TEM) observations indicated that only the PMN phase has hetero-epitaxially grown on the BaTiO3 seed particles. (C) 2002 Elsevier B.V. B.V. All rights reserved.