An interactive perspective of health education for the tropical disease control: the schistosomiasis case

Some municipalities in Brazil have been requesting orientation for the implementation of health education programs related to the control of schistosomiasis. This demand was based on experiences in the development of health education researches, strategies and materials for school-age children, involving the communities and secretaries of health and education. Motivated by this request and the recently implemented plan of health services (Unified Health System - Sistema Único de Saúde - SUS) that gives autonomy to the municipalities to utilize health resources and services in Brazil, this paper presents an interactive perspective of planning health education research and programs. The purpose of this perspective is to stimulate a reflection on the needs and actions of institutions and people involved in health education research and/or programs to obtain sustainability, commitment and effectiveness - not only in the control of schistosomiasis, but also in the improvement of environmental conditions, quality of life and personal health. This perspective comprises interaction among three levels related to health education programs: the decision level, the executive level and the beneficiary level. The needs and lines of action at each of these levels are discussed, as well as the ways in which they can interact with each other. This proposal may lead to useful interactive ways of planing, organizing, executing and evaluating health education research and/or program, not only towards the prevention and control of the disease at stake, but also to promote health in general.

Emission of nitrous oxide and carbon dioxide from semi-arid tropical soils in Chiapas México

The semi-arid region of Chiapas is dominated by N2 -fixing shrubs, e.g., Acacia angustissima. Urea-fertilized soil samples under maize were collected from areas covered and uncovered by A. angustissima in different seasons and N2O and CO2 emissions were monitored. The objective of this study was to determine the effects of urea and of the rainy and dry season on gas emissions from semi-arid soil under laboratory conditions. Urea and soil use had no effect on CO2 production. Nitrons oxide emission from soil was three times higher in the dry than in the rainy season, while urea fertilization doubled emissions. Emissions were twice as high from soil sampled under A. angustissima canopy than from arable land, but 1.2 lower than from soil sampled outside the canopy, and five times higher from soil incubated at 40 % of the water-holding capacity (WHC) than at soil moisture content, but 15 times lower than from soil incubated at 100 WHC. It was found that the soil sampling time and water content had a significant effect on N2O emissions, while N fertilizer and sampling location were less influent.

Pedological and isotopic relations of a highland tropical peatland, Mountain Range of the Espinhaço Meridional (Brazil)

The evolution of organic matter sources in soil is related to climate and vegetation dynamics in the past recorded in paleoenvironmental Quaternary deposits such as peatlands. For this reason, a Histosol of the mineralotrophic peatland from the Pau-de-Fruta Special Protection Area - SPA, Espinhaço Meridional, State of Minas Gerais, was described and characterized to evidence the soil constituent materials and properties as related to changes in environmental conditions, supported by the isotopic and elementary characterization of soil C and N and 14C ages. Samples were collected in a depression at 1,350 m asl, where Histosols are possibly more developed due to the great thickness (505 cm). Nowadays, the area is colonized by vegetation physiognomies of the Cerrado Biome, mainly rocky and wet fields (Campo Rupestre and Campo Úmido), aside from fragments of Semidecidual Seasonal Forest, called Capões forests. The results this study showed that early the genesis of the analyzed soil profile showed a high initial contribution of mostly herbaceous organic matter before 8,090 ± 30 years BP (14C age). In the lower-mid Holocene, between 8,090 ± 30 years AP (14C age) to ± 4,100 years BP (interpolated age), the vegetation gradually became more woody, with forest expansion, possibly due to increased humidity, suggesting the existence of a more woody Cerrado in the past than at present. Drier climate conditions than the current were concluded ± 2,500 years BP (interpolated age) and that after 430 years BP (14C age) the forest gave way to grassland, predominantly. After the dry season, humidity increased to the current conditions. Due to these climate fluctuations during the Holocene, three decomposition stages of organic matter were observed in the Histosols of this study, with prevalence of the most advanced (sapric), typical of a deposit in a highly advanced stage of pedogenetic evolution.

Arbuscular mycorrhizal inoculation increases biomass of Euterpe edulis and Archontophoenix alexandrae after two years under field conditions

Inoculation with arbuscular mycorrhizal fungi (AMF) of tree seedlings in the nursery is a biotechnological strategy to improve growth, survival after transplanting, biomass production and to reduce the use of fertilizers. Archontophoenix alexandrae and Euterpe edulis are palm species used in southern Brazil to produce the palm heart, the latter being included in the list of threatened species due to the overexploitation of its native population. The purpose of this paper was to evaluate the effect of mycorrhizal inoculation on growth and physiological parameters of A. alexandrae and E. edulis. After germination, the seedlings were inoculated (AMF) or not (CTL) with AMF in the treatments. Values of chlorophyll content, biomass and shoot phosphorus were not statistically different between the AMF and CTL treatments, after five months in the greenhouse. Inoculation with AMF significantly increased the levels of starch and soluble carbohydrates in shoots and roots of both species. Under field conditions, AMF had no effect on stem diameter and height after 12 and 24 months, but total plant biomass and leaf, stem and root biomass were greater in AMF than in CTL plants. The data indicated that AMF inoculation in the nursery has a strong effect on biomass accumulation after growing for 24 months under field conditions. Therefore, AMF inoculation should be considered an important strategy to increase growth and production of these economically important tropical palm species.

Transfer of cadmium and barium from soil to crops grown in tropical soils

Phytotoxicity and transfer of potentially toxic elements, such as cadmium (Cd) or barium (Ba), depend on the availability of these elements in soils and on the plant species exposed to them. With this study, we aimed to evaluate the effect of Cd and Ba application rates on yields of pea (Pisum sativum L.), sorghum (Sorghum bicolor L.), soybean (Glycine max L.), and maize (Zea mays L.) grown under greenhouse conditions in an Oxisol and an Entisol with contrasting physical and chemical properties, and to correlate the amount taken up by plants with extractants commonly used in routine soil analysis, along with transfer coefficients (Bioconcentration Factor and Transfer Factor) in different parts of the plants. Plants were harvested at flowering stage and measured for yield and Cd or Ba concentrations in leaves, stems, and roots. The amount of Cd accumulated in the plants was satisfactorily evaluated by both DTPA and Mehlich-3 (M-3). Mehlich-3 did not relate to Ba accumulated in plants, suggesting it should not be used to predict Ba availability. The transfer coefficients were specific to soils and plants and are therefore not recommended for direct use in risk assessment models without taking soil properties and group of plants into account.

Electrical Conductivity and Chemical Composition of Soil Solution: Comparison of Solution Samplers in Tropical Soils

ABSTRACT Soil solution samplers may have the same working principle, but they differ in relation to chemical and physical characteristics, cost and handling, and these aspects exert influence on the chemical composition of the soil solution obtained. This study was carried out to evaluate, over time, the chemical composition of solutions extracted by Suolo Acqua, with the hydrophilic membrane (HM) as a standard, using soils with contrasting characteristics, and to determine the relationship between electrical conductivity (EC) and concentration of ions and pH of soil solution samples. This study was carried out under laboratory conditions, using three soils samples with different clay and organic matter (OM) contents. Soil solution contents of F−, Cl−, NO−3, Br−, SO42−, Na+, NH4+, K+, Mg2+, Ca2+, were analyzed, as well as inorganic, organic, and total C contents, pH, and EC, in four successive sampling times. Soil solution chemical composition extracted by the Suolo Acqua sampler is similar to that collected by the HM, but the Suolo Acqua extracted more Na+ and soluble organic C than the HM solution. Solution EC, cation and anion concentrations, and soluble C levels are higher in the soil with greater clay and OM contents (Latossolo and Cambissolo in this case). Soil solution composition varied over time, with considerable changes in pH, EC, and nutrient concentrations, especially associated with soil OM. Thus, single and isolated sampling of the soil solution must be avoided, otherwise composition of the soil solution may not be correctly evaluated. Soil solution EC was regulated by pH, as well as the sum of cation and anion concentrations, and the C contents determined in the soil liquid phase.

Physiological responses of two tropical weeds to shade: I. Growth and biomass allocation

Ipomoea asarifolia (Desr.) Roem. & Schultz (Convolvulaceae) and Stachytarpheta cayennensis (Rich) Vahl. (Verbenaceae), two weeds found in pastures and crop areas in Brazilian Amazonia, were grown in controlled environment cabinets under high (800-1000 µmol m-² s-¹) and low (200-350 µmol m-² s-¹) light regimes during a 40-day period. For both species leaf dry mass and leaf area per total plant dry mass, and leaf area per leaf dry mass were higher for low-light plants, whereas root mass per total plant dry mass was higher for high-light plants. High-light S. cayennensis allocated significantly more biomass to reproductive tissue than low-light plants, suggesting a probably lower ability of this species to maintain itself under shaded conditions. Relative growth rate (RGR) in I. asarifolia was initially higher for high-light grown plants and after 20 days started decreasing, becoming similar to low-light plants at the last two harvests (at 30 and 40 days). In S. cayennensis, RGR was also higher for high-light plants; however, this trend was not significant at the first and last harvest dates (10 and 40 days). These results are discussed in relation to their ecological and weed management implications.

Tropical terrestrial model ecosystems for evaluation of soil fauna and leaf litter quality effects on litter consumption, soil microbial biomass and plant growth

The aim of this work was to evaluate whether terrestrial model ecosystems (TMEs) are a useful tool for the study of the effects of litter quality, soil invertebrates and mineral fertilizer on litter decomposition and plant growth under controlled conditions in the tropics. Forty-eight intact soil cores (17.5-cm diameter, 30-cm length) were taken out from an abandoned rubber plantation on Ferralsol soil (Latossolo Amarelo) in Central Amazonia, Brazil, and kept at 28ºC in the laboratory during four months. Leaf litter of either Hevea pauciflora (rubber tree), Flemingia macrophylla (a shrubby legume) or Brachiaria decumbens (a pasture grass) was put on top of each TME. Five specimens of either Pontoscolex corethrurus or Eisenia fetida (earthworms), Porcellionides pruinosus or Circoniscus ornatus (woodlice), and Trigoniulus corallinus (millipedes) were then added to the TMEs. Leaf litter type significantly affected litter consumption, soil microbial biomass and nitrate concentration in the leachate of all TMEs, but had no measurable effect on the shoot biomass of rice seedlings planted in top soil taken from the TMEs. Feeding rates measured with bait lamina were significantly higher in TMEs with the earthworm P. corethrurus and the woodlouse C. ornatus. TMEs are an appropriate tool to assess trophic interactions in tropical soil ecossistems under controlled laboratory conditions.

Growth of champa fruit under agroecological conditions of Miraflores, Boyacá, Colombia

The objective of this work was to analyze the growth of champa fruit (Campomanesia lineatifolia) as a function of growing-degree days (GDD) in the municipality of Miraflores, in Boyacá, Colombia. Thirty trees were selected at random, and 100 flowers in full bloom were marked in each tree. From the 26th day after flowering until harvest, 10 samples were taken every 15 days to determine the fruit parameters and growth rate. Temperature was recorded to calculate the GDD. From flowering until harvest, 1,489.1 GDD were accumulated over 145 days. Dry and fresh matter mass of pulp, seed, and total fruit were fitted to a logistic growth model, and three growth stages (S1, S2 and S3) were defined. In the S1, growth was slow, and the relative growth remained nearly stable, whereas the absolute growth rate (AGR) increased slowly. In the S2, maximum growth was observed. In the S3, which corresponds to maturation, dry mass increased gradually, and the AGR decreased, while the fresh pulp and total mass did not cease to increase. The polar and equatorial diameters increased linearly, while the volume followed an exponential model. Champa fruit show a simple sigmoid growth curve.

Inheritance of late flowering in natural variants of soybean cultivars under short-day conditions

The objective of this work was to determine the inheritance of the long juvenile period trait in natural variants of the Doko, BR 9 (Savana), Davis, Embrapa 1 (IAS 5RC), and BR 16 soybean cultivars. Complete diallel crosses were made between the Doko and BR 16 cultivars and their variants. A 3:1 segregation ratio was observed in the F2 populations of the 'Doko' x Doko-18T, 'Doko' x Doko-Milionária, 'Davis' x São Carlos, and 'BR 9 (Savana)' x MABR92-836 (Savanão) crosses, indicating that the long juvenile period trait is controlled by a pair of recessive genes. The difference in late flowering between the Doko cultivar and both of its variants was caused by a recessive spontaneous mutation at the same genetic locus. However, the variants Doko-18T and Doko-Milionária are identical mutants that share a pair of genes that control the long juvenile period under short-day conditions. These mutants can be used in breeding programs to develop cultivars adapted to low-latitude tropical regions.

O papel dos sulfetos volatilizados por acidificação no controle do potencial de biodisponibilidade de metais em sedimentos contaminados de um estuário tropical, no sudeste do Brasil

Measurements of acid volatile sulfide (AVS) and simultaneously extracted metals (SEM) were combined in order to verify the ecological hazard of contaminated sediments from the Santos-Cubatão Estuarine System (SE Brazil), which is located in one of the most industrialized areas in the Latin America. Intertidal sediments from the Morrão River estuary were collected seasonally in short cores. The redox conditions, organic matter contents and grain-size were the main controlling factors on SEM distribution. However, clear relationships among these variables and AVS were not observed. The molar SEM/AVS ratios were frequently > 1 especially in the summer, suggesting major metal bioavailability hazard in this humid hot season.

Influência da temperatura, umidade e profundidade do solo na persistência do diurom e sulfato de endossulfam em um solo tropical

The influence of temperature (30 and 40 ºC) and soil humidity (20, 50 and 70% of water holding capacity) on the degradation of the herbicide diurom and the endosulfan metabolite, endosulfan sulfate was studied under laboratory conditions, in different soil layers (0-30, 30-38 and 38-83 cm) of an Oxisol (Yellow Latosol) collected in an agricultural area of Mato Grosso State, Brazil. Endosulfan sulfate was rapidly degraded under lower soil humidity, higher temperature and deeper soil layers. For diurom the opposite was observed as a consequence of its higher water solubility and lower soil sorption coefficient.

Biodegradação de alcoóis, ftalatos e adipatos em um solo tropical contaminado

The adipic and phthalic acid esters are plasticizers, have low water solubility, high partition octanol/water coefficients (Kow) and accumulate in soil and sediments. These compounds are considered teratogenic, carcinogenic and endocrine disruptors chemicals. This study evaluated the bioremediation of tropical soil contaminated with plasticizers process wastes, in aerobic conditions, with and without introduction of acclimated bacteria. It was selected 200 kg of contaminated tropical soil for the biodegradation study. The plasticizers concentrations in soil ranged between 153 mgDOA/kg up to 15552 mgDIDP/kg and after 90 days of biodegradation, the lower removal efficiencies were 72% with a 1-2 log simultaneous bacterial growth.

Lipídios como indicadores de fontes e distribuição de matéria orgânica particulada em um complexo estuarino-lagunar tropical (Mundaú-Manguaba, AL)

Fatty acids, alcohols and sterols were considered as markers of the source and distribution of particulate organic matter during the dry season in the Mundaú-Manguaba estuarine-lagoon system, NE Brazil. Lipid composition showed an overwhelming influence of autochthonous sources of organic matter in all system´s compartments, including the probable occurrence of algal blooms in specific areas. On the other hand, contamination by sewage was restricted to Mundaú lagoon. This scenario differed from known conditions observed in the wet season, illustrating the usefulness of the lipid biomarker approach for the characterization of other complex and dynamic systems in the Brazilian coastal zone.

Chlorophyll fluorescence of tropical tree species in a semi-deciduous forest gap

The characterization of different ecological groups in a forest formation/succession is unclear. To better define the different successional classes, we have to consider ecophysiological aspects, such as the capacity to use or dissipate the light energy available. The main objective of this work was to assess the chlorophyll fluorescence emission of tropical tree species growing in a gap of a semi-deciduous forest. Three species of different ecological groups were selected: Croton floribundus Spreng. (pioneer, P), Astronium graveolens Jacq. (early secondary, Si), and Esenbeckia febrifuga A. Juss. (late secondary, St). The potential (Fv/Fm) and effective (deltaF/Fm') quantum efficiency of photosystem II, apparent electron transport rate (ETR), non-photochemical (qN) and photochemical (qP) quenching of fluorescence were evaluated, using a modulated fluorometer, between 7:30 and 11:00 h. Values of Fv/Fm remained constant in St, decreasing in P and Si after 9:30 h, indicating the occurrence of photoinhibition. Concerning the measurements taken under light conditions (deltaF/Fm', ETR, qP and qN), P and Si showed better photochemical performance, i.e., values of deltaF/Fm', ETR and qP were higher than St when light intensity was increased. Values of qN indicated that P and Si had an increasing tendency of dissipating the excess of energy absorbed by the leaf, whereas the opposite was found for St. The principal component analysis (PCA), considering all evaluated parameters, showed a clear distinction between St, P and Si, with P and Si being closer. The PCA results suggest that chlorophyll fluorescence may be a potential tool to differentiate tree species from distinct successional groups.