Scielo RSS <![CDATA[Acta Botanica Brasilica]]> vol. 29 num. 1 lang. <![CDATA[SciELO Logo]]> <link></link> <description>This study aimed to evaluate the growth, assimilate partitioning and seed vigor expression of rye seeds subjected to waterlogging during development. The experimental design was completely randomized with six replications and three treatments. The treatments involved different waterlogging periods: a) no waterlogging; b) single waterlogging of three days; and c) two soil waterlogging periods of three days. The plants were collected at regular intervals of 14 days after emergence until the end of the growth cycle, measuring the dry matter accumulation and the leaf area for growth analysis and dry matter partition between the organs and number of flowers. The other calculated indices included the harvest index and relative seedling emergence rate originating from the seeds of plants that were maintained at field capacity and under the effect of soil waterlogging. Rye plants that were not subjected to waterlogging had a higher dry matter, dry matter production rates and harvest index compared to the plants under the effect of two soil waterlogging periods. Plants under the effect of two waterlogging periods showed drastic alterations in their growth rates and assimilate partitioning during development, and seed vigor expression was negatively affected when the plants were subjected to soil waterlogging.</description> </item> <item> <title/> <link></link> <description> Ageratum has a complex circumscription, and recent studies have indicated its polyphyletism. The genus has been placed in the tribe Eupatorieae whose embryology is not fully known. Embryological data are conservative and important indicators of phylogenetic relationships and can improve family relationships. This study presents, for the first time in Eupatorieae, embryological data for Ageratum conyzoides and A. fastigiatum. Both species have common features of the family such as a unitegmic anatropous ovule, basal placentation, secretory tapetum, Polygonum megagametophyte, and Asterad embryogenesis. The data obtained reinforce the heterogeneity of the family embryology and show, for the first time, the anther wall development of the monocotyledonous type for Asteraceae. The species studied show also differences between themselves. A. conyzoides has bisporangiated and introrse anthers, conspicuous pappus, and cypselae with trichomes on the ribs, whereas A. fastigiatum has tetrasporangiate and latrorse anthers, pappus absent at maturity, and glabrous cypselae. The data presented support recent phylogenetic molecular studies, suggesting the replacement of A. fastigiatum to another genus along with Gyptidinae.</description> </item> <item> <title/> <link></link> <description>The northeastern Brazilian Atlantic forest is the region with the greatest diversity of bryophytes in the country. However, knowledge about bryophytes is irregularly distributed among Brazilian regions. Therefore, we aimed to contribute to knowledge about bryophytes on a regional scale in the northeastern Atlantic forest, to identify the centers of bryophyte diversity in that region, and to reiterate the importance and identify locations for which new protected areas should be created. We built a database of bryophytes in 23 locations of the region, based on a literature review and new floristic inventories. To identify the locations of greatest relevance to bryophyte conservation, we considered 1) total and endemic species richness, 2) phylogenetic diversity (PD), and 3) functional diversity (proportion of shade specialists). The northeastern Atlantic rainforest contains 396 spp., representing 26% of the taxa occurring in the country, 13 of which are endemic. Generalist species predominated (164 spp.), followed by shade (133 spp.) and sun (92 spp.) specialists. The Murici Ecological Station had the highest richness, number of endemic species, and phylogenetic diversity.</description> </item> <item> <title/> <link></link> <description>Serra do Cipó has attracted the interest of many researchers over the years because of its unique characteristics, particularly the fact that the site represents the transition between Cerrado and Atlantic Forest. The study area of Serra do Cipó is located along a gallery forest "córrego Três Pontinhas," at 19°16'00" S and 43°32'49" W and an altitude of 1,188 m. The objective of this study was to survey the Division Bryophyta in a gallery forest within the National Park of Serra do Cipo, Minas Gerais. Collections were made during the months of November 2009 and July 2011. We found 15 families, 26 genera, 43 species, and 4 varieties of mosses. The families with the largest number of species were Leucobryaceae (10), Sematophyllaceae (9), and Calymperaceae (6). Other families included Fissidentaceae (3), Bryaceae, Pylaisiadelphaceae, Pottiaceae, and Orthotrichaceae (2 spp. each); Brachytheciaceae, Cryphaeaceae, Fabroniaceae, Helicophyllaceae, Hypnaceae, Polytrichaceae, and Sphagnaceae had only 1 sp. each. Three new records for the state of Minas Gerais were found: Acroporium caespitosum, A. longirostre, and Colobodontium vulpinum.</description> </item> <item> <title/> <link></link> <description> Restinga forests are commonly known to be plant communities rather poor in tree species. This study aimed to describe and explain the association between the floristic-structural similarities and the environmental conditions in three Swamp Restinga Forest communities in southern Brazil. In 13 plots of 100 m2 each, we sampled all individual trees (circumference at breast height &gt;12 cm and height ≥3 m). We collected soil samples in each plot for chemical and textural analyses. Phytosociological parameters were calculated and different structural variables were compared between areas. The density of individuals did not differ between areas; however, the maximum height and abundance of species differed between the site with Histosols and the other two sites with Gleysols. Further, a canonical correspondence analysis based on a matrix of vegetation and that of environmental characteristics explained 31.5% of the total variation. The high floristic and environmental heterogeneity indicate that swamp-forests can shelter many species with low frequency. Most species were generalists that were not exclusive to this type of forest. Overall, our study showed that swamp-forests within the same region can show considerable differences in composition and structure and can include species-rich communities, mostly due to the presence of species with a broader distribution in the Atlantic Rainforest domain on sites with less stressful environmental conditions and without waterlogged conditions.</description> </item> <item> <title/> <link></link> <description>In Orchidaceae, association with symbiotic fungi is required for seed germination and seedling development, thereby being the main energy source during the first steps of germination. Colombia is one of the countries with the greatest biodiversity of orchids, with an estimated 3,200 species, but few studies on orchid mycorrhiza have been conducted. In our study, we isolated and sequenced the internal transcribed spacer rDNA region of fungi from two co-occurring Colombian epiphytic orchids, I. utricularioides and P. pusilla, both belonging to the subtribe Oncidiinae. All sequences were recognized as belonging to the genus Ceratobasidium, known to be a common orchid mycorrhizal fungus in both tropical and temperate orchids. One sequence was 100% similar to fungi isolated from I. utricularioides in Costa Rica in a previous study. I. utricularioides was confirmed to be a specialist, associating with only one clade of mycorrhizal fungi. However, P. pusilla was shown to be a generalist, associating with three clades. This finding indicates that the variation in mycorrhizal specificity could be an important factor in the co-existence of orchids. The high affinity between the subtribe Oncidiinae and Ceratobasidium was also reinforced.</description> </item> <item> <title/> <link></link> <description>We studied the management of the fiber-producing chambira palm Astrocaryum chambira by indigenous people in the Colombian Amazon. Between 2009 and 2012, we visited four communities and two marketing centers, where we interviewed 12 people. In addition, we specifically observed A. chambira harvesting, processing, and commercialization; studied palm populations at five localities; measured leaf production rate; and integrated secondary data. At least 21 aboriginal groups in the Colombian Amazon use chambira fiber. The palm grows in association with human communities, and it has been widely used and managed in past agroforestry systems. The fiber is obtained from the unexpanded leaves of juvenile or adult palms, and harvesting is often unsustainable because of overharvesting acaulescent palms or of cutting down adult palms. This is leading to a depletion of palm population. Annual leaf production rate was 1.59-2.89 leaves/palm year−1, which is lower than that reported in other studies. Based in our results, we recommended a harvest of 1 leaf/palm year−1 in acaulescent palms, and 1-2 leaves/palm year−1 in stemmed palms. Chambira-derived products are mostly handicrafts for marketing, and their trade represents 40%-100% of artisan household cash income. Improving the management of chambira palms requires the introduction of non-destructive harvest techniques and a wider use of the palm in agroforestry systems. An analysis of traditional management practices and of the role of chambira among Amerindian people indicates that A. chambira was an incipient domesticate at the time of the European conquest.</description> </item> <item> <title/> <link></link> <description>The upper montane forests in the southern and southeastern regions of Brazil have an unusual and discontinuous geographic distribution at the top of the Atlantic coastal mountain ranges. To describe the floristic composition and structure of the Atlantic Forest near its upper altitudinal limit in southeastern Brazil, 30 plots with 10 × 10 m were installed in three forest sites between 2,200 and 2,300 m.a.s.l. at Serra Fina. The floristic composition and phytosociological structure of this forest were compared with other montane and upper montane forests. In total, 704 individuals were included, belonging to 24 species, 15 families, and 19 genera. Myrsinaceae, Myrtaceae, Symplocaceae, and Cunoniaceae were the most important families, and Myrsine gardneriana, Myrceugenia alpigena, Weinmannia humilis, and Symplocos corymboclados were the most important species. The three forest sites revealed differences in the abundance of species, density, canopy height, and number of stems per individual. The upper montane forests showed structural similarities, such as lower richness, diversity, and effective number of species, and they tended to have higher total densities and total dominance per hectare to montane forests. The most important species in these upper montane forests belong to Austral-Antartic genera or neotropical and pantropical genera that are typical of montane areas. The high number of species shared by these forests suggests past connections between the vegetation in southern Brazilian high-altitude areas.</description> </item> <item> <title/> <link></link> <description>We investigated the occurrence of associations between overstory and understory tree species in a semideciduous tropical forest. We identified and measured all trees of nine canopy species with diameter at breast height ≥4.8 cm in a 10.24 ha plot and recorded all individuals beneath their canopies ("understory individuals") within the same diameter class. The total density of understory individuals did not significantly differ under different overstory species. One overstory species (Ceiba speciosa) showed higher understory species richness compared with five other species. There was a strong positive association between three overstory species (Esenbeckia leiocarpa, Savia dictyocarpa, and C. speciosa) and the density of seven understory species (Balfourodendron riedelianum, Chrysophyllum gonocarpum, E. leiocarpa, Holocalyx balansae, Machaerium stipitatum, Rhaminidium elaeocarpum, and S. dictyocarpa). These results probably reflect the outcome of a complex set of interactions including facilitation and competition, and further studies are necessary to better understand the magnitude and type of the effects of individual overstory species on understory species. The occurrence of species-specific associations shown here reinforces the importance of non-random processes in structuring plant communities and suggest that the influence of overstory species on understory species in high-diversity forests may be more significant than previously thought.</description> </item> <item> <title/> <link></link> <description>The Brazilian Atlantic Forest is considered a global hotspot for biodiversity although it is currently threatened and highly fragmented. Orchidaceae in this phytogeographical domain is represented by 148 genera, of which 142 are endemic; Rio de Janeiro State contains approximately one third of all Brazilian orchid species. The Wildlife Protection Zone of the Palmares Environmental Protection Area (ZVS da APA Palmares) is located in the municipality of Paty do Alferes in Rio de Janeiro State and forms a mosaic of Dense Ombrophilous Forest fragments together with other conservation areas in the state. We surveyed Orchidaceae at 12 collection sites between July 2010 and February 2012 and analyzed floristic similarities between the collection sites and between 12 fragments of dense ombrophilous forest in Brazil utilizing PAST software and the Sørensen coefficient. The survey identified 27 genera and 43 species. Low indices of similarity among the areas were observed as well as weak support for grouping the ZVS da APA Palmares with the Serra da Tiririca Mountains. Greater conservation efforts are recommended for remnant fragments of Dense Ombrophilous Forest.</description> </item> <item> <title/> <link></link> <description> Schinopsis brasiliensis is an endangered tree species found in the Caatinga biome. It presents a characteristic slow development and difficult propagation, although it has been traditionally exploited in the region. Application of arbuscular mycorrhizal fungi (AMF) and phosphorus (P) fertilization may be beneficial to S. brasiliensis development at the seedling stage, which at the same time may help species conservation and the recovery of degraded areas in the Caatinga biome. We assessed the response of S. brasiliensis to AMF inoculation (Claroideoglomus etunicatum and Acaulospora longula) and P fertilization (0, 12, 24, and 48 mg dm−3 addition of P2O5). S. brasiliensis responded positively to both AMF inoculation and P fertilization. At low P concentrations, the inoculated plants showed higher leaf area and enhanced vegetative development, nutrient content and biomass production compared with non-inoculated plants. Conversely, increasing levels of P fertilization decreased the level of mycorrhizal colonization, plant responsiveness to inoculation, and spore production in C. etunicatum. Thus, P concentrations were able to influence the response of S. brasiliensis to mycorrhization and responsiveness to increased mycorrhization with the decrease in P availability. These results showed that mycorrhizal symbiosis plays an essential role in the development of S. brasiliensis. </description> </item> <item> <title/> <link></link> <description>This paper presents a comparative description of the starch distribution in the anthers, microspores and pollen grains of Aechmea recurvata, Dyckia racinae and Tillandsia aeranthos. Flowers at different stages of development were processed according to plant microtechniques for observation by light microscope. Ten stages of embryological development were used as references for the comparative analysis of starch distribution and dynamics. The structural data showed a greater starch accumulation in the parietal layers and connective of D. racinae. It was observed that in the species studied, starch began to accumulate in microspore mother cell stage. The pollen grains in D. racinae and in T. aeranthos present two amylogenesis-amylolysis cycles, while A. recurvata presents only one. One amylogenesis-amylolysis cycle occurs in the parietal layers and/or connective tissue in all three species. The pollen grains in the three species are dispersed without starch and are characterized as the starchless type. Starch dynamics presents a close relation to the development of sporangia, microspores and pollen grains. It is believed that differences in the starch distribution and accumulation are related to the abiotic factors where the species are found.</description> </item> <item> <title/> <link></link> <description>This study aimed to define the current status of ethnobotanical research in Brazil based on published scientific articles and to detect current knowledge gaps in Brazil's ethnobotany. A database, including articles published in national and international scientific journals from 1988 to 2013, was gathered for this purpose. This report discusses the growing number of publications in ethnobotanical research and the main techniques used in the discipline. To identify current knowledge gaps, his report emphasizes the main focus of the different studies, target regions, and communities targeted or involved in the original study. Most publications focused on the northeast and southeast Brazil, and the most frequently studied biomes were the Caatinga and Atlantic forest. Further, the most frequently studied communities were located in rural areas, although the number of studies focused in urban areas has been steadily increasing. A lack of human resources in ethnobotanical research and a lack of current studies in the Amazon, Cerrado, Pampa, and Pantanal regions were the main identified gaps. These data provide a basis for future studies and investments aimed at strengthening ethnobotanical research in Brazil.</description> </item> <item> <title/> <link></link> <description>The present study reconstructs the paleovegetation of a varzea (seasonally flooded) forest in the central parts of the Madeira River floodplain in Brazil using palynological data. Forty-nine cut-bank sediment samples from the Madeira River were processed in the study; from these, ten samples contained pollen: two contained pollen from the Middle Pleniglacial age, one contained pollen from the Tardiglacial age, six contained pollen from the Holocene, and one contained more recently deposited pollen. The Middle Pleniglacial pollen belonged to a primary succession varzea forest, while the Tardiglacial pollen represented a late succession varzea forest. On the other hand, the three Holocene samples showed the characteristic composition of chavascal (water-logged forest) or lacustrine varzea forest, and three samples belonged to a late succession varzea forest. The most recent pollen deposit represented a secondary succession varzea forest. This paleovegetation showed a typical mosaic distribution, which may be explained by the fluvial dynamics, high species richness and diversity in the varzea forest, and the presence of dominant species.</description> </item> <item> <title/> <link></link> <description>To evaluate their diagnostic value in systematic studies, seed coat morphology for 16 taxa from 11 genera of Cucurbitaceae were examined using stereomicroscopy and scanning electron microscopy. The taxa included representatives of the tribes Benincaseae, Bryonieae, Coniandreae, and Luffeae in order to evaluate their diagnostic value in systematic studies. Macro- and micromorphological characters of their seeds are presented, including shape, color, size, surface, epidermal cell shape, anticlinal boundaries, and periclinal cell wall. The taxonomic and phylogenetic implications of seed coat micromorphology were compared with those of the available gross morphological and molecular data. Seed character analysis offered useful data for evaluating the taxonomy of Cucurbitaceae on both intrageneric and tribal levels. Monophyly of the tribes Bryonieae, Coniandreae, and Luffeae was supported. Moreover, these analyses supported previous biochemical and phylogenetic data, indicating that distinct lineages are present within the tribe Benincaseae, that this tribe is not monophyletic, and that the subtribe Benincasinae is highly polyphyletic. A key is provided for identifying the investigated taxa based on seed characters.</description> </item> <item> <title/> <link></link> <description>We present a floristic survey of the genus Tetrapterys (Malpighiaceae) from the Brazilian Midwest, including morphological descriptions, keys, comments on taxonomy and phenology, illustrations, and distribution maps for all species. Nine species were found in the studied area: T. ambigua, T. crispa, T. discolor, T. hassleriana, T. jussieuana, T. microphylla, T. mucronata, T. racemulosa, and T. ramiflora. The distribution of species shows a collection gap mostly in northern States of Mato Grosso and southeastern Mato Grosso do Sul. Only T. ambigua and T. ramiflora were found in all federal units within the Brazilian Midwest, and three species were recorded for just one, T. hassleriana and T. racemulosa in Mato Grosso do Sul, and T. microphylla in Goiás, restricted to the Chapada dos Veadeiros.</description> </item> <item> <title/> <link></link> <description>We studied the pollination biology of Canna paniculata (Cannaceae), a plant species common in the Atlantic Rainforest of southeastern Brazil. The species presents specialized ornithophilous flowers, which in our study area are solely pollinated by the hermit hummingbird Phaethornis eurynome. Although C. paniculata is capable of bearing fruit after self-pollination, it requires pollinators for reproduction. We discuss the importance of hermit hummingbirds for the reproduction of specialized ornithophilous plants such as C. paniculata, including their asymmetric dependence on hermit hummingbirds - core pollinators in Neotropical forest ecosystems.</description> </item> </channel> </rss> <!--transformed by PHP 04:04:46 28-04-2015-->