Seed Dispersal Anachronisms: Rethinking the Fruits Extinct Megafauna Ate

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of water stress on seed germination and seedling growth in Oryza sativa L.

The effect of water stress induced by application of polyethylene glycol 6000 during seed germination and seedling growth of Oryza sativa L. cv. IAC 165 was analysed. The seed germination was inhibited by the decrease in the water potential of the medium, the inhibition being greater under white light than under continuous darkness. When the seedling was submitted to water stress (-0.51 MPa) white light inhibited growth of root, coleoptile-and leaf, while under no stress conditions white light caused increase in growth of root and leaf and only inhibition of coleoptile growth. © 1990 Kluwer Academic Publishers.

Toxicologic evaluation of acute and subacute oral administration of Cucurbita maxima seed extracts to rats and swine

The extract prepared from dried seeds of Cucurbita maxima was administered to rats and pigs. Following a single dose or 4 weeks of daily oral administration, the extract produced no changes in serum glucose, urea, creatinine, total protein, uric acid, GOT, GPT, LDH or blood counts. Urine analysis (urea, uric acid, creatinine, total protein, Na and K), as well as histopathological investigation, showed no abnormalities. These results taken as a whole indicate that the seeds of C. maxima as used in Brazilian folk medicine are not toxic for rats and swine.

Use of sorghum seed tissue as a biocatalyst in a stirred reactor for oxalic acid determination

The enzyme oxalate oxidase, E.C. 1.2.3.4 from Sorghum vulgare seeds (variety BR303) was used to develop a new sensor for oxalate determination without any purification. The sorghum seeds were conditioned in a 0.10 mol I-1 KCl solution. Then, these seeds were put in a stirring bar type enzymic reactor and coupled with an electrode for CO2. This device was introduced into a cell containing 10.0 ml of a 0.10 mol I-1 KCl solution saturated with oxygen. This sensor showed a linear response between 1.0 and 4.0 × 10-3 mol I-1 with a slope of 30 mV per decade of oxalate concentration at 25.0°C. The sensor was stable for one month or 200 determinations. The response time was about 60 s. The Michaelis-Menten constant determined for this enzyme was 1.5 × 10-3 mol I-1.

Systematic position of Xyris: Flower and seed anatomy

Flower anatomy, embryology, and seed anatomy are described for some Brazilian species of Xyris section Nematopus and reviewed with respect to the systematic position of Xyris and allied taxa in Commelinanae. Apart from tenuinucellate ovules (shared with Poales, Mayaca, and Eriocaulaceae), Xyris lacks some of the synapomorphies of other genera that are sometimes included in Xyridaceae (Aratitiyopea, Achlyphila, Abolboda, and Orectanthe), such as inaperturate spinulate pollen; Xyris has monosulcate reticulate pollen. There is an unusual degree of variation among different genera of Xyridaceae for characters such as tapetum type, indicating that the monophyly of the family requires testing. However, while several characters indicate two generic groups, there is much missing critical information for embryological and seed coat characters in other Xyridaceae.

Seed production of species belonging to the palm collection of the FCAV-UNESP, Jaboticabal, state of Sao Paulo, Brazil

The seed production of fully developed specimens belonging to the palm collection of the Experimental Nursery of the FCAV-UNESP was observed. This paper gives information useful for nursery growers: average fruit weight, seed germination, procedures for sowing, time of fruit harvest and possibility of seed storage. At the nursery, the time until the first seedling emerged has varied, according to the species, from one to more than ten months. For better germination, fruits must be collected when completely mature; the fleshy mesocarp must be removed before sowing. Seed storage for a few months has been possible for some species, by removing the fleshy mesocarp, drying the seeds in shade, treating them with a fungicide, packing them in plastic bags and maintaining the seed lots at 20°C. These results agree with reports about some other species and general recommendations of the related literature.

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. romanzqffiana 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 apical, 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.

Effect of five substrates and three seed types on Calendula officinalis (Asteraceae) germination and seedling development

The investigation was carried out during May - June 1996 in Agronomical Sciences College - UNESP, Campus de Botucatu. The objective was to study the effect of seed types (carenate, alate and orbicular) and different substrates (vermiculite, sand, soil, commercial mixture and producer's mixture) on Calendula officinalis germination and seedling development. The design was in randomized blocks, with 4 replications. The germination index of the seeds was evaluated, as well as the development of aerial part and root system of the seedlings. Results showed that seed types have no relation with seedling development, therefore, germination was better on alate and orbicular seeds in C. officinalis. With reference to the substrates, the producer's mixture and the commercial mixture gave better germination and seedling development.

Economic viability and selection of irrigation systems using simulation and stochastic dominance

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

Effect of barium titanate seed particles on the sintering and lattice parameters in PbMg1/3Nb2/3O3 ceramics

PbMg1/3Nb2/3O3 (PMN) powder was prepared by citrate organic solution, and barium titanate (BT) seed particles were added to encourage the perovskite phase formation. Sintering was followed using the constant heating rate mode of a dilatometer, and it was observed that the seed concentration affected the PMN shrinkage rate and crystal structure. The study of the lattice parameters of the samples after the sintering process indicates that the diffusion of the titanium and of the barium inside perovskite and pyrochlore PMN phases occurs. Moreover, this substitution provoked a decrease of the lattice parameters as showed by the Rietveld refinement.

A new rain-operated seed dispersal mechanism in Bertolonia mosenii (Melastomataceae), a Neotropical rainforest herb

Although widespread among fungi, lichens, liverworts, and mosses, seed dispersal mechanisms operated by rain are unusual among flowering plants. Generally speaking, two mechanisms are involved in seed dispersal by rains: the splash-cup and the springboard. Here we describe a new seed dispersal mechanism operated by rain in a Neotropical rainforest herb Bertolonia mosenii Cogniaux (Melastomataceae). The study was carried out at the lowland Atlantic rainforest, southeastern Brazil. We experimentally demonstrate that rain is necessary to release the seeds from the capsules through what we call squirt-corner seed dispersal mechanism: when a raindrop strikes the mature fruit, the water droplet forces the seeds outward to the angles (corners) of the triangular capsule and the seeds are released. As far as we know squirt-corner represents a new rain-operated seed dispersal mechanism, and a novel seed dispersal mode both for Melastomataceae and for flowering plants from Neotropical forests.

Viability of Streptococcus mutans on transparent and opaque toothbrushes.

PURPOSE: The objective of this study was to evaluate the viability of the microorganism Streptococcus mutans on toothbrushes made of opaque and transparent materials. METHODS: Twenty-eight toothbrushes (14 opaque and 14 transparent) were inoculated in tubes with brain heart infusion (BHI) broth of a standard strain of S. mutans and incubated in candle jars at 37 degrees C for 24 hours. Both the opaque and transparent toothbrushes were removed at T = 0 h (control); T = 0.5 h; T = 1 h; T = 2 h; T = 4 h; T = 8 h; and T = 24 h. Individual toothbrushes were subjected to agitation in a saline solution and samples of the solution were diluted and inoculated in Bacitracin Sucrose Agar--SB-20. RESULTS: After half an hour (T2) there was a significant decrease in the number of microorganisms on the transparent and opaque toothbrushes, respectively 6.0 x 10(5) and 9.4 x 10(5), when compared to the control. After the T3 = 1 hour, T4 = 2 hours, T5 = 4 h, the number of microorganisms decreased from 4.1 x 10(5); 2.1 x 10(5); 1.4 x 10(5); and 9.2 x 10(5); 5.7 x 10(5); 1.2 x 10(5) to zero (0.0) in T6 = 8 h, respectively on the transparent and opaque toothbrushes. The reduction in viable microorganisms was more obvious with the transparent toothbrushes, although the number of viable microorganisms was not significantly different for the two types of toothbrushes at the end of the experiment, T5 = 1.4 x 10(5) (transparent) and T5 = 1.2 x 10(5) (opaque). CONCLUSIONS: With both opaque and transparent toothbrushes, the number of microorganisms decreased with time. A reduction in the number of microorganisms on the transparent toothbrushes was observed following inoculation and incubation. This suggests the transparent toothbrushes inhibit the viability of the S. mutans.