Developing countries' anti-cyclical policies in a globalized world

Includes bibliography

Allelopathic effects of aqueous extract of Brassica napus on germination of seeds of Phaseolus vulgaris

Secondary compounds produced by plants are considered an alternative method of weed suppression but can cause negative effects on crops in succession, especially in a no-tillage system, due to the degradation of crop residues with allelopathic potential. The objective of this work was to analyze the influence of foliar aqueous extracts of Brassica napus on the germination and initial development of seedlings of Phaseolus vulgaris. The extract was prepared as a stock 10 % weight/volume solution, and diluted into treatments of relative concentrations of 100 % (i.e. 10 % w/v stock), 75 %, 50 %, 25 % and 0 % (untreated control consisting of distilled water), in a completely randomized design. The seeds of Phaseolus vulgaris were moistened with the differing concentrated extracts and kept in a germination chamber at 25 °C, with a photoperiod of 12 h for nine days. The variables evaluated were: percentage germinating, first count of germination and germination velocity index, as well the root and hypocotyl length, and fresh and dry mass of the seedlings. The aqueous leaf extracts of Brassica napus did not influence the germination of Phaseolus vulgaris seeds, but did induce the growth of abnormal seedlings by inhibition of secondary roots and reduced prominence of the primary root.

Caracterização morfológica do diásporo e da plântula de Archontophoenix cunninghamii (Arecaceae)

The palm Archontophoenix cunninghamii H.Wendl. & Drude, even widely used in landscaping, has been poorly studied. In general, there are few articles on morphology of seeds and seedlings of Arecaceae species. With the aim of filling this gap, the objective of the present work describes the diaspore (seed with adhering endocarp) and the seedling morphology. A. cunninghamii seeds present rounded shape and a ruminated endosperm of hard consistency. The embryo is lateral, peripheral and relatively undifferentiated, approximately 4 mm long, conical, with one of the extremities convex, and in its inside there is a small protuberance while the other extremity is rounded and narrower. The seedling is adjacent ligulated and hypogeal, with the development starting from a mass of undifferentiated cells in the micropillar depression, the differentiation of shoot and root primordium, being the first enveloped by a sheath closed. The root system is fasciculate, with different adventitious roots and several lateral roots with few absorbent hairs. The stem comprises three sheaths surrounding the first young leaf, which are opened in succession, permitting the emergence of the primary bifid leaf, with typical parallel nerves.

Análises técnicas e econômicas no sistema de integração lavoura-pecuária submetido à adubação nitrogenada

Sustainable agriculture, reduced production costs and adding value to the system are achieved through the use of agricultural areas throughout the year, in integrated or mixed system. The study aimed to determine the technical coefficients to estimate and evaluate the operational cost and profitability indicators of the consortium of corn with two species of Brachiaria (B. brizantha, MG-5 and B. ruziziensis). The crops were submitted to N rates (0, 100, 200, 300 e 400kg ha-1year-1) at sidedressing, using urea, and winter common bean in succession, in crop-livestock integration under no-tillage, in irrigated conditions, in 2008/2009 agricultural year in Cerrado region (Selvíria - MS). The experiment was conducted in a randomized complete block design with four replications in a 2 x 5factorial. It was concluded thatcathe inputs were the components that most increased the producing cost of corn and common bean in the ILP study. The total operational cost has increased as a function of increasing doses of N. In all treatments the levels of profitability were positive indicating the viability of the system. The treatment that showed the best technical and economic performance was intercropped with corn and B. brizantha, fertilized with 100kg ha-1year-1N and common bean in succession.

Seedling morphology and development in the epiphytic cactus Epiphyllum phyllanthus (L.) Haw. (Cactaceae: Hylocereeae)

Seedling morphology is relevant in classification, taxonomy, and vegetation studies to understand plant life cycles, germination succession and requirements, and developmental progression. However, most morphological studies of seedlings lack analysis of organ anatomy, impeding the comprehension of series of development and establishment in a particular environment. Here, we have taken a traditional anatomical approach to examine the stages of seedling development in Epiphyllum phyllanthus, a holo-epiphytic cactus of tribe Hylocereeae. The goals were 1) to offer a comprehensive description of growth series in E. phyllanthus seedlings based on morphological and anatomical analysis and 2) to examine the initial growth phases in the life cycle of this species to identify organ development and understand their adaptive significance in relation to seedling establishment. Our results include descriptions of seed morphology, embryonic features, and seedling vascularization pattern in the root, hypocotyl, cotyledons, and epicotyl. The morphological and developmental patterns in E. phyllanthus seedlings have potential phylogenetic and ontogenetic implications in the Cactaceae. Characters such as the presence of mucilage on the seed coat, the lack of seed operculum, and large cotyledons in E. phyllanthus are comparable to basal cacti, but the root anatomy is more similar to columnar relatives. At the familial level, there is an apparent trend in decreasing number of phloem and xylem poles in the stele of primary root, correlated with degree of specialization and advanced phylogenetic position: tetrarch to septarch-octarch in basal lineages, tetrarch Cereus-type in columnar species, to the diarch vascular system in Rhipsalideae and some species with cylindric/globose stem. © Torrey Botanical Club.

Can savannas become forests? A coupled analysis of nutrient stocks and fire thresholds in central Brazil

Aims: The effects of fire ensure that large areas of the seasonal tropics are maintained as savannas. The advance of forests into these areas depends on shifts in species composition and the presence of sufficient nutrients. Predicting such transitions, however, is difficult due to a poor understanding of the nutrient stocks required for different combinations of species to resist and suppress fires. Methods: We compare the amounts of nutrients required by congeneric savanna and forest trees to reach two thresholds of establishment and maintenance: that of fire resistance, after which individual trees are large enough to survive fires, and that of fire suppression, after which the collective tree canopy is dense enough to minimize understory growth, thereby arresting the spread of fire. We further calculate the arboreal and soil nutrient stocks of savannas, to determine if these are sufficient to support the expansion of forests following initial establishment. Results: Forest species require a larger nutrient supply to resist fires than savanna species, which are better able to reach a fire-resistant size under nutrient limitation. However, forest species require a lower nutrient supply to attain closed canopies and suppress fires; therefore, the ingression of forest trees into savannas facilitates the transition to forest. Savannas have sufficient N, K, and Mg, but require additional P and Ca to build high-biomass forests and allow full forest expansion following establishment. Conclusions: Tradeoffs between nutrient requirements and adaptations to fire reinforce savanna and forest as alternate stable states, explaining the long-term persistence of vegetation mosaics in the seasonal tropics. Low-fertility limits the advance of forests into savannas, but the ingression of forest species favors the formation of non-flammable states, increasing fertility and promoting forest expansion. © 2013 Springer Science+Business Media Dordrecht.

Lower Permian stems as fluvial paleocurrent indicators of the Parnaíba Basin, northern Brazil

A comprehensive biostratinomic study was carried out with abundant stems from the Lower Permian Motuca Formation of the intracratonic Parnaíba Basin, central-north Brazil. The fossils represent a rare tropical to subtropical paleofloristic record in north Gondwana. Tree ferns dominate the assemblages (mainly Tietea, secondarily Psaronius), followed by gymnosperms, sphenophytes, other ferns and rare lycophytes. They are silica-permineralized, commonly reach 4 m length (exceptionally more than 10 m), lie loosely on the ground or are embedded in the original sandstone or siltstone matrix, and attract particular attention because of their frequent parallel attitudes. Many tree fern stems present the original straight cylindrical to slightly conical forms, other are somewhat flattened, and the gymnosperm stems are usually more irregular. Measurements of stem orientations and dimensions were made in three sites approximately aligned in a W-E direction in a distance of 27.3 km at the conservation unit Tocantins Fossil Trees Natural Monument In the eastern site, rose diagrams for 54 stems indicate a relatively narrow azimuthal range to SE. These stems commonly present attached basal bulbous root mantles and thin cylindrical sandstone envelopes, which sometimes hold, almost adjacent to the lateral stem surface, permineralized fern pinnae and other small plant fragments. In the more central site, 82 measured stems are preferentially oriented in the SW-NE direction, the proportion of gymnosperms is higher and cross-stratification sets of sandstones indicate paleocurrents mainly to NE and secondarily to SE. In the western site, most of the 42 measured stems lie in E-W positions. The predominantly sandy succession, where the fossil stems are best represented, evidences a braided fluvial system under semiarid conditions. The low plant diversity, some xeromorphic features and the supposedly almost syndepositional silica impregnation of the plants are coherent with marked dry seasons. Thick mudstones and some coquinites below and above the sandy interval may represent lacustrine facies formed in probably more humid conditions. The taphonomic history of the preserved plants began with exceptional storms that caused fast-flowing high water in channels and far into the floodplains. In the eastern site region, many tree ferns only fell, thus sometimes covering and protecting plant litter and leaves from further fragmentation. Assemblages of the central and western sites suggest that the trees were uprooted and transported in suspension (floating) parallel to the flow. Heavier ends of stems (according to their form or because of attached basal bulbous root mantle or large apical fronds) were oriented to upstream because of inertial forces. During falling water stage, the stems were stranded on riverbanks, usually maintaining the previous transport orientation, and were slightly buried. The perpendicular or oblique positions of some stems may have been caused by interference with other stems or shallow bars. Rare observed stems were apparently waterlogged before the final depositional process and transported as bedload. The differences of interpreted channel orientations between the three sites are expected in a braided fluvial system, considering the very low gradients of the basin and the work scale in the order of tens of kilometers. The mean direction of the drainage probably was to east and the flows apparently became weaker downstream. This study seems to provide reliable data for paleocurrent interpretations, especially considering areas with scarce preserved sedimentary structures. © 2013 Elsevier Ltd.

Dose-response of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] in the urothelial mucosa of Wistar rats

Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] is a herbicide that induced urothelial tumors in the urinary bladder of Wistar rats fed 2500. ppm during a long-term study. The currently suggested non-genotoxic mode of action (MOA) of diuron encompasses in succession urothelial necrosis induced by direct cytotoxicity, regenerative cell proliferation and sustained urothelial hyperplasia that increases the likelihood of neoplasia development. This study evaluated the dose-response profile of urothelial histological and ultrastructural lesions induced by diuron. Sixty male Wistar rats were fed ad libitum diuron mixed in the diet at 0, 60, 125, 500, 1250, or 2500. ppm for 20 weeks. The incidences of urothelial simple hyperplasia and the cell proliferation index were significantly increased in the diuron-fed 1250 and 2500. ppm groups. By scanning electron microscopy, the incidences and severity of lesions were significantly increased in the 500 and 1250. ppm groups. The incidences of urothelial hyperplasia in the kidney pelvis were significantly increased in the 500, 1250 and 2500. ppm groups. The present study documents the dose-response influence of diuron on the rat urothelium, with a no observed effect level (NOEL) at 125. ppm; 1250. ppm was as effective as 2500. ppm at inducing urothelial lesions. © 2013 Elsevier B.V.

Can overharvesting of a non-timber-forest-product change the regeneration dynamics of a tropical rainforest? The case study of Euterpe edulis

The exploitation of non-timber forest products is often considered a low-impact activity in tropical forests. However, assessments of the impacts of such activity are mostly focused on the harvested species and not on the plant community, thus limiting our understanding for establishing forest management recommendations. We investigated the consequences of Euterpe edulis palm heart harvesting on the seed rain in the Brazilian Atlantic rainforest. We compared the density of E. edulis individuals, as well as the density of E. edulis seeds, and the density, richness and functional composition of seed rain of the whole plant community, before and after palm heart harvesting in a 10 ha permanent plot. This assessment was carried out in preserved (typical old-growth Atlantic rainforest) and in disturbed (more open habitat dominated by the native bamboo Guadua tagoara) forest patches. Palm harvesting reduced the E. edulis population from 202.16 to 25.67 ind/ha and its seed rain density from 0.362 to 0.3 seeds/m2 and from 2.395 to 0.15 seeds/m2 in preserved and disturbed forest patches, respectively. Seed density of light-dependent climbers, pioneer trees, bamboo and animal-dispersed seeds increased after palm harvesting, especially in the disturbed forest patches, where palm harvesting was more intense and may have changed the light regime of the understory. On the other hand, species richness of the plant community declined by half. We observed a remarkable decline in the number of animal-dispersed species, especially for those with large seeds, suggesting that the activity of seed dispersers, including many species attracted by E. edulis fruits, was reduced. Therefore, harvesting of E. edulis palm heart may change the regeneration dynamics of the Atlantic rainforest, both due to shifts in forest structure, mediated by the removal of individuals from the forest canopy, and in community functioning, mediated by the interference on the activity of seed dispersers. © 2013 Elsevier B.V. All rights reserved.

Adubação nitrogenada e inoculação com rizóbio no feijoeiro em sucessão ao milho consorciado com braquiárias no sistema plantio direto

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Persistência de palhada de plantas de cobertura em função de doses de silício e resposta do feijoeiro em sucessão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resposta do feijoeiro (Phaseolus vulgaris L.) à adubação nitrogenada de cobertura em dois sistemas de manejo de solo

Pós-graduação em Agronomia (Agricultura) - FCA

A chuva no Distrito Federal: o regime e as excepcionalidades do ritmo

Pós-graduação em Geografia - IGCE

O clima do oeste do Paraná: análises da presença do lago de Itaipu

Pós-graduação em Geografia - IGCE

Análise dos processos de decomposição e sucessão ecológica em carcaças de suínos (Sus scrofa L.) mortos por disparo de arma de fogo e overdose de cocaína e protocolo de procedimento diante de corpo de delito

Pós-graduação em Biologia Geral e Aplicada - IBB