Antonieta Nassif Salomão

Polyembryony in angiospermous trees of the Brazilian Cerrado and Caatinga vegetation

The occurrence of polyembryony was investigated in 75 woody species of the Cerrado in central Brazil and the xerophilous Caatinga vegetation in northeastern Brazil. Fourteen species showed polyembryony, a type of anomalous angiospermous reproduction. Polyembryony is reported for the first time for nine genera, Astronium, Byrsonima, Cariniana, Copaifera, Hancornia, Magonia, Myracrodruon, Tabebuia, and Tapirira. The positive correlation found between polyembryony, sexual reproduction, and apomictic processes suggests that a number of angiospermous species may make regular use of multiple breeding systems.

Germinação de espécies arbóreas de floresta estacional decidual do vale do rio Paranã em Goiás após três tipos de armazenamento por até 15 meses

Seed dispersal in tropical deciduous forests occurs mostly in the dry season and germination at the onset of the rainy season. The delay of the first rains and dry spells are major mortality factors in dry forest regions. Storing seeds to plant during the constant rains could increase germination and seedling survival. We investigated the germination percentage of deciduous forest tree species after being stored i) at -20 °C and -196 °C (liquid nitrogen), and ii) at natural conditions for three and 15 months. Seeds of 19 tree species of deciduous forests of Parana river basin, Goias state, were collected from August to October 2005. Two experiments were run: i) storage for three and 15 months in brown bags at environmental temperature, ii) storage for 72 hours at -20 °C cameras, liquid nitrogen (-196 °C) and a control. Storage at environmental temperature decreased germination of only two species after three months, Cordia trichotoma (73 to 38%) and Copaifera langsdorffii (85 to 65%). Three species decreased germination after 15 months (Cordia trichotoma, 73 to 5%; Cavanillesia arborea, 77% to 12%; and Anadenanthera colubrina, 93% to 76%) and two species, Aspidosperma pyrifolium and Tabebuia impetiginosa, lost completely their germination. Temperatures -20 and -196 °C decreased germination of only one species each, Tabebuia impetiginosa (90 to 70%) and Aspidosperma pyrifolium (90 to 43%), respectively. In general, environmental temperature storage up to 15 months and -20 and -196 °C storage were efficient to preserve seed germinability of many dry forest tree species from Parana river basin. These are feasible options to ex situ conservation and to increase germination for direct seeding strategies of restoration.

Estrutura populacional de regenerantes de Copaíba (Copaifera langsdorffii Desf.) em mata ciliar do Distrito Federal

The population structure of seedlings and saplings of Copaifera langsdorffii Desf. was studied in a gallery forest in the Distrito Federal, Brazil, as an aid for definition of in situ conservation strategies for the species. Transects were made, with all adults being plotted. Seedlings were also mapped and observed for predation or desease, with high degrees of both being present, with no correlation with adults proximity. Seedling density was correlated with open areas (gaps). It was estimated that all regenerants observed were over two years old, based on two to tree years periodicity in flowering and fruiting patterns for this trees species in the study area. This suggests very low grwth rates, suggesting that in situ conversation of both adults and seedlings is a viable alternative for this species.

Phytosociological survey in Brazilian forest genetic reserve of Caçador

A phytosociological survey was carried out in the Forest Genetic Reserve of Caçador, which belongs to the Brazilian Agriculture Research Corporation – EMBRAPA. The Genetic Reserve comprises an area of 1120 ha and has been managed by the Agricultural Research and Extension Corporation of the State of Santa Catarina (EPAGRI). A restricted random sampling by plots, with units of 2500 m2 (100 x 25 m) was used, allocating 40 plots to stands containing Araucaria angustifolia. All trees with diameter ≥ 20 cm at breast height were measured. Frequency, density, dominance, soil coverage, and importance value were evaluated, The most important species indicated by these parameters were Araucaria angustifolia, Ocotea porosa, Cupania vernalis, Matayba eleagnoides, Mollinedia elegans, Ocotea pulchella, Ilex paraguariensis and Prunus brasiliensis. In spite of the very high mean basal area (35.84 m2 ha-1), mean density (222 trees ha-1) and mean volume outside bark (531.14 m3 ha-1) for A. angustifolia it was found that understory had low commercial value and a very low natural regeneration rate in the priority species for in situ conservation: A. angustifolia, Cedrela fissilis, I. paraguariensis, Mimosa scabrella, P. brasiliensis and O. porosa. Simpsons index has shown in this case a low floristic diversity of species however, as was expected, the highest levels of abundance, dominance and frequency were found for Araucaria angustifolia.

Armazenamento de sementes de girassol em temperaturas subzero: aspectos fisiológicos e bioquímicos

The significant progress in Brazilian agricultural production has been due its capacity to incorporate and use genetic resources. Embrapa Genetic Resources and Biotechnology is the institution responsible for the long-term conservation of the seed germplasm of many crops, stored at -20 °C. Appropriate storage is necessary for correct germplasm management, to ensure the quality of the material stored and minimize the deterioration process. The objectives of this study were to evaluate the effect of seed water content on the tolerance to storage at sub-zero temperatures of -20 °C and -196 oC, to associate the tolerance level with physiological and biochemical aspects and to verify the effect of the pre-humidification of seeds on physiological quality after storage. Seed quality was evaluated by tests of electrical conductivity, first and final count of germination and determination of the peroxide index. Sunflower seeds can be dried to 3.2% of water content in silica gel or in a drying chamber and stored at -20 °C or -196 °C without loss of germination and vigor. Seed deterioration, evaluated by the peroxide index, was lower in seeds stored in NL. The humidification treatment was important for the evaluation of seedlings in the first count of germination test and the electrical conductivity test.

Germinação de sementes de Passiflora setacea e dormência induzida pelo armazenamento

). A germinacao foi conduzida em papel germitest embebido em agua. O teste de tetrazolio foi empregado para verificar a viabilidade das sementes apos os periodos de armazenamento. Foi possivel verificar que: (i) as sementes de P. setacea podem ser desidratadas ate atingir, aproximadamente 4,7% de agua (base umida) sem perda da capacidade de germinacao; (ii) o armazenamento de sementes com baixo teor de agua, a baixas temperaturas pode induzir a dormencia de sementes de P. setacea; (iii) a dormencia e superada pelo tratamento das sementes com acido giberelico, ate o quinto mes de armazenamento; (iv) as sementes conservadas sob temperaturas subzero apresentaram maior porcentagem de viabilidade em relacao as armazenadas a 4 °C. Diante destes resultados, pode-se concluir que sementes de P. setacea podem ser conservadas por ate 8 meses, sob baixas temperaturas, a -20 ou -196 °C, pois mantem os padroes minimos de viabilidade estabelecidos internacionalmente.Termos para indexacao: maracuja do mato, viabilidade, conservacao, acido giberelico.GERMINATION OF Passiflora s

Validation of quality tests for forest seed species

The Brazilian literature on seed germination testing of tropical forest species, although still insufficient, is extensive for species with economical potential. However, this information is still fragmented and often reported in scientific communications of modest circulation. In this summary, we present the results of a validation process for germination tests on Brazilian forest species, which had as a starting point the ample reviewing of current methods, besides exhaustive pre-testing in certified laboratories. Specific protocols were created for each species, including substrate, temperature, seed disinfection, breaking of dormancy, seedling classification and other information. These protocols were sent to research laboratories and accredited by the Ministry of Agriculture, together with seed lots of three distinct qualities. The presuppositions of normality of the residuals and homoscedasticity of the variations were previously tested and the completely randomized factorial design statistical model was applied to the normal seedlings of each species. After this analysis, germination test methods for seeds of Astronium fraxinifolium , Ceiba speciosa , Cybistax antisyphilitica , Enterolobium contortisiliquum , Guazuma ulmifolia , Lafoensia pacari , Mimosa caesalpiniaefolia , Peltophorum dubium , Pseudobombax tomentosum and Pterogyne nitens, all forest species of different Brazilian biomes, were considered to be validated.

Expression of stress-related genes in zebrawood (Astronium fraxinifolium, Anacardiaceae) seedlings following germination in microgravity

Seeds of a tropical tree species from Brazil, Astronium fraxinifolium, or zebrawood, were germinated, for the first time in microgravity, aboard the International Space Station for nine days. Following three days of subsequent growth under normal terrestrial gravitational conditions, greater root length and numbers of secondary roots was observed in the microgravity-treated seedlings compared to terrestrially germinated controls. Suppression subtractive hybridization of cDNA and EST analysis were used to detect differential gene expression in the microgravity-treated seedlings in comparison to those initially grown in normal gravity (forward subtraction). Despite their return to, and growth in normal gravity, the subtracted library derived from microgravity-treated seedlings was enriched in known microgravity stress-related ESTs, corresponding to large and small heat shock proteins, 14-3-3-like protein, polyubiquitin, and proteins involved in glutathione metabolism. In contrast, the reverse-subtracted library contained a comparatively greater variety of general metabolism-related ESTs, but was also enriched for peroxidase, possibly indicating the suppression of this protein in the microgravity-treated seedlings. Following continued growth for 30 days, higher concentrations of total chlorophyll were detected in the microgravity-exposed seedlings.

Comportamento de regenerantes de Astronium urundeuva (Fr. All.) Engler em área sob ação antrópica

The behaviour of seedlings and coppice-regenerants of Astronium urundeuva was observed in a pasture. A ratio of 1,7 and 2 regenerants for each seedling was recorded. Spatial distribution of Astronium seedlings and coppiceregenerants proved to be clustered rather than randomly dispersed. Vegetative regeneration seems to have played a more important role in the maintenance of the species in the study area when compared to sexual reproduction. This is probably due to competition between pasture species and the seedlings in the early stages of establishment. However, onde established, seedlings seem to do very well. When methods for in situ conservation are being proposed for Astronium it is important to consider not only seedlings but also coppice-regenerants, as it is almost impossible, at present, to conserve the species in areas without human disturbance.

Viability Assessment of Genipa americana L. (Rubiaceae) Embryonic Axes after Cryopreservation Using In Vitro Culture

Embryonic axes excised from seeds of Genipa americana L. desiccated to different water contents were successfully cryopreserved by rapidly plunging seed samples directly into liquid nitrogen. Control and cryopreserved embryonic axes were excised and grown in WPM culture medium for viability assessment. All control embryonic axes (−LN2) excised from fully hydrated seeds (43.89% moisture content) germinated after 21 days of culture in vitro. These high germination percentages persisted even after the water content of the seeds was as low as 6.79%. After freezing in liquid nitrogen high germination percentages, 93%, 96%, and 93%, were observed for embryonic axes excised from seeds dehydrated to 13.26%, 9.57%, and 6.79 moisture content, respectively. The cryopreservation technique described here is recommended for long term conservation of G. americana germplasm.