33 resultados para O41 - One, Two, and Multisector Growth Models


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A 14-year-old female patient became pregnant 6 years after heart transplantation. The pregnancy evolved uneventfully, and the newborn infant was healthy. Five months after delivery, the mother was in good condition with preserved ventricular function, and the baby had normal neuro-psychomotor development. Even though the case reported here was a success, pregnancy following cardiac transplantation is considered a high-risk condition and remains contraindicated.

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Food utilization by the larvae of Toxorhynchites splendens (Wiedemann) was studied in the laboratory by offering larvae of Aedes aegypti Linnaeus, Anopheles stephensi (Liston), and Culex quinquefasciatus (Say). Quantitative analyses of data indicated that immature development was significantly faster with increase in food availability. The regression analysis showed that the degrees of the relationship between immature duration (Id) and food availability were higher when offered early instars of prey (first and second instars) than late instars. Consumption rate (Cr) of the predator increased with increase in food availability and this relationship was highly significant when larvae of An. stephensi were offered as food. Consumption rate to food level decreased with increase in the age class of the prey. There was a significant negative correlation between Id and Cr. This aspect helps to increase population turnover of T. splendens in a shorter period when the prey is abundant. Conversely, the predator compensated the loss in daily food intake at low food level by extending Id thereby attains the minimum threshold pupal weight for adult emergence. There was an increase in the relative growth rate (RGR) of the predator when An. stephensi was offered as prey and this was related to the high protein content of the prey per body weight. There was a positive correlation between Cr and RGR. This adaptive life characteristic strategy of this predator is useful for mass-rearing for large scale field release programmes in the control of container breeding mosquitoes is discussed.

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Soil and fertilizer management during cultivation can affect crop productivity and profitability. Long-term experiments are therefore necessary to determine the dynamics of nutrient and root distribution as related to soil profile, as well as the effects on nutrient uptake and crop growth. An 18-year experiment was conducted at the Federal University of Rio Grande do Sul State (UFRGS), in Eldorado do Sul, Brazil, on Rhodic Paleudult soil. Black oat and vetch were planted in the winter and corn in the summer. The soil management methods were conventional, involving no-tillage and strip tillage techniques and broadcast, row-and strip-applied fertilizer placement (triple superphosphate). Available P (Mehlich-1) and root distribution were determined in soil monoliths during the corn grain filling period. Corn shoot dry matter production and P accumulation during the 2006/2007 growing season were determined and the efficiency of P utilization calculated. Regardless of the degree of soil mobilization, P and roots were accumulated in the fertilized zone with time, mainly in the surface layer (0-10 cm). Root distribution followed P distribution for all tillage systems and fertilizer treatments. Under no-tillage, independent of the fertilizer placement, the corn plants developed more roots than in the other tillage systems. Although soil tillage systems and fertilizer treatments affected P and root distribution throughout the soil profile, as well as P absorption and corn growth, the efficiency of P utilization was not affected.

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The objective of this work was to evaluate the efficiency of ectomycorrhizal isolates on root colonization, phosphorus uptake and growth of Eucalyptus dunnii seedlings. Inocula of ten ectomycorrhizal isolates of Chondrogaster angustisporus, Hysterangium gardneri, Pisolithus spp., and Scleroderma spp. were aseptically produced in a peat-vermiculite mixture supplemented with liquid culture medium. Plants grew in a similar substrate supplemented with macro-and micro-nutrients; treatments were randomly distributed in a greenhouse. After three months, seedlings inoculated with three isolates - UFSC-Sc68 (Scleroderma sp.), UFSC-Ch163 (Chondrogaster angustisporus), and UFSC-Pt188 (Pisolithus microcarpus) - had a phosphorus shoot content and a shoot dry matter higher or equivalent to those of noninoculated controls which had been fertilized with a 16-fold phosphorus amount. These isolates were selected for new studies for establishing inoculum production techniques, in order to be applied in reforestation programmes under nursery and field conditions.

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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.

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Beckwith-Wiedemann syndrome is a genetic syndrome characterized by macroglossia, omphalocele, fetal gigantism and neonatal hypoglycemia. The authors report a case of Beckwith-Wiedemann syndrome diagnosed in a 32-year-old primigravida in whom two-dimensional ultrasonography revealed the presence of abdominal wall cyst, macroglossia and polycystic kidneys. Three-dimensional ultrasonography in rendering mode was of great importance to confirm the previous two-dimensional ultrasonography findings.

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Physiological and biochemical aspects of assai palm during seed germination and early seedling growth were investigated. Seeds collected from plants growing in flooded and upland forests were used to determine the influence of normoxic (aerobic) and anoxic (anaerobic) conditions in germination and the initial and average time of development in the roots and shoots. After 75 days, seedlings germinated under normoxia were transferred to trays and submitted to flooding. Seed reserves (lipids, proteins, soluble sugars and starch) were monitored for quiescent and germinated seeds maintained under normoxic and anoxic conditions, as well as after 5, 10 and 20 days of seedling growth. Alcohol dehydrogenase (ADH) activity was quantified in roots and leaves of seedlings without or with flooding (partial and total). Seeds were not able to germinate under anoxia. Different strategies of storage mobilization of lipids, proteins, soluble sugars and starch were observed in seeds of each environment. ADH activity was induced by anoxia, with the highest level observed in the leaves. This study showed that, under normoxic conditions, the best developmental performance of assai palm seeds, from flooded or upland forest areas, during germination was associated with primary metabolites mobilization and seedling flooding tolerance with increased ADH activity. We conclude that the assai palm is well adapted to the anoxic conditions provoked by flooding.

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ABSTRACT The productivity of Eucalyptus at plantations is increasing and has undergone a variety of research studies. Most research is dealing with simple dendrometric variables like the DBH (diameter at breast height) and tree height, or more complex variables including crown parameters or variables concerning photosynthesis. The root systems, however, have not been well analyzed yet. The objective of the study was to analyze the root system with a non-destructive method and to evaluate possible correlations with dendrometric variables of the tree (DBH, height, crown expansion). A small experimental plantation with 39 even-aged, 6-year-old trees of Eucalyptus grandis x urophylla has been investigated within this study. The results of the study show the highest correlation of the root areas with the crown expansion. In general, the root area shows a significantly bigger expansion in the eucalypt plantation than the tree crown, with a more homogeneous development.

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Soil incorporation of crop residues can lead to weed suppression by posing allelopathic and physical effects. Allelopathic potential of the crops sorghum, sunflower, brassica applied as sole or in combination for horse purslane (Trianthema portulacastrum) suppression was evaluated in a pot investigation. Chopped crop residues alone and in combination were incorporated at 6 g kg-1 soil (12 t ha-1), and a weedy check was maintained. Germination traits time to start germination; time to 50% emergence, mean emergence time, emergence index and final germination percentage were negatively influenced by residue incorporation. Crop residues also exerted a pronounced negative influence on the shoot and root length of horse purslane. Significant suppression in leaf and root score and leaf area per plant was also observed. A combination of sorghum and sunflower residues accounted for maximum (71%) seedling mortality. Soil incorporation of allelopathic crop residues can be employed for horse purslane management.

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Conyza canadensis is a widespread weed species forming dense populations in most regions of China. Petri dish bioassays with aqueous extracts of the aboveground parts and roots of C. canadensis at three concentrations (0.05, 0.1, and 0.2 g mL-1) were undertaken to investigate the autotoxic effects of C. canadensis, and the possible effects on three dominant native weed species, Plantago asiatica, Digitaria sanguinalis and Youngia japonica. The results showed that seed germination and the shoot length of three native species were significantly inhibited by aqueous extracts of C. canadensis at almost all concentrations that generally increased with increasing extract concentration. However, the seed germination and shoot length of C. canadensis itself was not significantly affected by the same extracts at all concentrations. These results suggested that the potential allelopathic compounds produced by the tissue of C. canadensis may contribute to its invasive success in invading southern China.

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Sorghum, pearl millet, and Brachiaria ruziziensis have similar characteristics which have led to their use for mulch formation in no-till systems. This study was carried out to evaluate the potential of these three species as straw suppliers to suppress weed emergence. Initial findings led to the conclusion that both pearl millet and Brachiaria ruziziensis have similar or superior potential as weed suppressors, compared to sorghum straw, a species with recognized allelopathic potential. Subsequently, new trials were conducted under greenhouse conditions by sowing weed species in pots, followed by covering of the soil with the straw under evaluation. Independent experiments were conducted for Euphorbia heterophylla and Bidens pilosa. In each experiment, the factors analyzed were type of straw (pearl millet and B. ruziziensis), amount of straw (equivalent to 4 and 8 t ha-1 dry mass) and irrigation method (surface and subsurface). Both pearl millet and B. ruziziensis have shown to be species that can be cultivated to produce straw with allelopathic potential. These effects were effective in suppressing the emergence or early growth of E. heterophylla and B. pilosa. There was no difference in the suppression of emergence of these species when the soil cover level was alternated between 4 and 8 t ha-1 dry mass.

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Herbicides and plant growth regulators are often used in sugarcane management. However, the use of non-selective pesticides can cause adverse effects on the efficiency of beneficial insects in integrated pest management. Within this context, this study aimed to evaluate the effect of such products on the immature stages of the parasitoid Trichogramma galloi. Eggs of Diatraea saccharalis containing the parasitoid at the egg-larva stage and at the prepupal and pupal stages were immersed in test solutions of the following pesticides (maximum recommended doses for sugarcane): herbicides clomazone and diuron + hexazinone, and plant growth regulators trinexapac-ethyl and sulfometuron-methyl. The biological properties evaluated were emergence (F1 and F2) and number of eggs parasitized by T. galloi (F1). The products were classified according to percentage of reduction in emergence and parasitism: harmless (<30%), slightly harmful (30-79%), moderately harmful (80-99%) and harmful (>99%). The pesticides evaluated were considered to be harmless or slightly harmful to immature T. galloi and, thus, their use should be preferred for preserving this parasitoid species in sugarcane management programs.

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The technology that employs genetic modifications brought a significant increase in the utilization of glyphosate. Transgenic soybean has been suffering injury, even though it possesses a resistance mechanism to glyphosate. Currently, there are only a few studies on the dynamics of glyphosate in transgenic soybean planted in soils with different textures interacting with phosphorus concentrations. This study focused on assessing the effects of glyphosate in transgenic soybean plants on different types of soil and at different phosphorus levels. The experimental design was completely randomized, in factorial design: 2 x 6 x 3, that being 2 soil types, 6 doses of glyphosate and 3 levels of phosphorus, and four replications. Plants were cultivated for thirty days in pots with two types of soil, one being clayey (Red-Yellow Latosol) and the other sandy (Quartzarenic Neosol). They received one, two, and three times the maintenance dose of fertilization of phosphorus, corresponding to: 170, 250 and 330 kg of P2O5 ha-1 to QN, and 380, 460 and 540 kg P2O5 ha-1 to RYL, respectively. Glyphosate was applied at six different doses: 0, 1,200, 2,400, 12,000, 60,000 and 120,000 g ha-1 of active ingredient. Plant height, a and b chlorophyll, and shoot were lower for the plants that received lower doses of glyphosate, regardless of the type of soil. Greater availability of phosphorus and lower amount of glyphosate used in Quartzarenic Neosol soil provided for less phytointoxication symptoms in transgenic soybean.

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Vochysia tucanorum Mart. (Vochysiaceae) is a very widely distributed species in the cerrado and forests in Brazil, from the State of Bahia to Paraná. Its seed germination was analysed under eight treatments using different conditions of light and temperature. Up to 73 days, at least ca. 93% of the seeds germinated in all treatments, except under alternating temperatures of 35°/10°C (62%). Light enhanced germination, except under constant temperature of 25°C when seeds are not photoblastic. At this temperature, the highest percentage of germination was found. Initial vegetative growth was analysed by comparing the effects of shading, by means of different percentages of full daylight (100%, 45%, 10.6%, 4.8%), and soils from cerrado and forest. During 123 days, no mortality was recorded and cotyledons persisted on the seedlings of all treatments. In general, the seedlings of V. tucanorum were found to be more or less indifferent to the soil from cerrado or forest and shading seems to promote height increment. However, total dry mass was larger under a radiation of 45% full daylight and smaller under extreme conditions (100% or 4.8% full daylight).

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Sapindus saponaria (soapberry) is a species that presents a great diversity of chemical compounds, such as saponins; however, few studies have examined the allelopathic effect of this species. Therefore, this study provides an evaluation of the allelopathic potential of aqueous extracts of the roots and mature leaves of S. saponaria on the germination of diaspores and seedlings growth of lettuce (Lactuca sativa) and onion (Allium cepa). The aqueous extract was prepared in the proportion of 100 g of dry plant material in 1,000 mL of distilled water (a concentration of 10% w v-1), and diluted with distilled water to 7.5, 5.0 and 2.5% concentrations. The mature leaf extracts caused delay and decrease in the germination process of the lettuce and onion diaspores, with inhibitory effect concentration-dependent, while the root extracts showed no allelopathic effects on the germination process. Both extracts caused abnormalities and inhibited the growth of shoot and root seedlings.