Showing papers by "Universidade Federal Rural do Rio de Janeiro published in 2005"

The Potential of C4 Perennial Grasses for Developing a Global BIOHEAT Industry

Abstract: Unprecedented opportunities for biofuel development are occurring as a result of rising fossil fuel prices, the need to reduce greenhouse gases, and growing energy security concerns. An estimated 250 million hectares (ha) of farmland could be utilized globally to develop a bioenergy industry if efficient and economical perennial biomass crops and bioenergy conversion systems are employed. In temperate zones, C4 or warm-season grass research and development efforts have found switchgrass (Panicum virgatum) and Miscanthus capable of producing biomass yields of 10 to 20 oven dried tonnes (ODT)/ha/yr, while in tropical areas Erianthus and napier grass (Pennisetum purpureum) are producing 25 to 35 ODT/ha/yr. The potential to annually produce 100 barrels of oil energy equivalent/ha with a 25:1 energy output to input ratio appears achievable with high-yielding, N-fixing warm-season grasses grown on marginal lands in the tropics. Commercialization of densified herbaceous plant species has been slow because of the...

Decomposição e liberação de nitrogênio de resíduos culturais de plantas de cobertura em um solo de cerrado

Abstract: Dry mass production, decomposition rate and nitrogen (N) release were evaluated in a field experiment under seven cover crop types: pearl millet (Pennisetum americanum sin. typhoides), brachiaria grass (Brachiaria brizantha), sorghum (Sorghum bicolor L. Moench), pigeon pea (Cajanus cajan (L.) Mill sp), sunn hemp (Crotalaria juncea) and black oat (Avena strigosa Schreb), compared to a fallow and a traditional cropping system (control) in a cerrado soil (Uberaba-MG, Brazil). Among the tested cover crops, pearl millet and sunn hemp presented higher dry mass yield and nitrogen accumulation and release. Brachiaria grass had the highest decomposition rate and shortest half-life time. All crops reached the highest N liberation rate 42 days after desiccation.

Monitoring of resistance to the pyrethroid cypermethrin in Brazilian Aedes aegypti (Diptera: Culicidae) populations collected between 2001 and 2003

Abstract: Resistance to cypermethrin of different Aedes aegypti Brazilian populations, collected at two successive periods (2001 and 2002/2003), was monitored using the insecticide-coated bottles bioassay. Slight modifications were included in the method to discriminate between mortality and the knock down effect. Although this pyrethroid was recently started to be used in the country to control the dengue vector, a decrease in susceptibility was noted between both periods analyzed, particularly in the city of Rio de Janeiro. The results indicate that resistance is due at least in part to a target site alteration.

Parasites of Cynoscion guatucupa along South American Atlantic coasts: evidence for stock discrimination

Abstract: Two stocks of striped weakfish Cynoscion guatucupa in the south-west Atlantic Ocean, were identified using parasites as biological tags. A total of 297 fish caught in Brazil, Uruguay and Argentina, contained 29 species of metazoan parasites. Univariate analysis on parasite populations, as well as multivariate discriminant analysis, calculated for juvenile and adult fish separately, allowed the identification of the two stocks, one from Argentina and Uruguay and the other from Brazil, to be made. Southern samples were characterized by higher prevalences and abundance of larval endohelminths, whereas in the northern stock, gastrointestinal and ectoparasitic species were common. Discriminant analyses on parasite infracommunities of Brazilian fish showed notable differences between juvenile and adult hosts; no such trend was observed in fish from Argentina and Uruguay, despite differences between juveniles and adults at the population level. Different oceanographic conditions and their influence on the distribution of parasites as well as of other hosts involved in their life cycles could be key factors for the differences observed among stocks of C. guatucupa.

Community structure of metazoan parasites of the yellow Cururu toad, Bufo ictericus [Anura, Bufonidae] from Rio de Janeiro, Brazil

Abstract: Thirty-two specimens of Bufo ictericus (Spix, 1824), 22 males and 10 females, collected in Miguel Pereira, State of Rio de Janeiro, Brazil, from April 2002 to August 2003, were examined for presence of metazoan parasites. Thirty-one (97%) specimens of B. ictericus were parasitized by one or more metazoan species. Sixteen species of parasites were collected: 2 digeneans, 13 nematodes, and 1 ixodid tick. The endoparasites represented 82.3% of the total number of parasite specimens collected. Bufo ictericus is a new host record for: Gorgoderina parvicava Travassos, 1922, Oswaldocruzia lopesi Freitas et Lent, 1938, O. mazzai Travassos, 1935, O. subauricularis (Rudolphi, 1819), Oxyascaris sp., Parapharyngodon alvarengai Freitas, 1957, Rhabdias elegans Gutierrez, 1945 and R. sphaerocephala Goodey, 1924. The digenean Mesocoelium monas (Rudolphi, 1819) was the most abundant species and the ixodid Amblyomma rotundatum (Koch, 1844) was the most prevalent in the parasite community of B. ictericus. The metazoan parasite species of B. ictericus showed the typical aggregated pattern of distribution of most parasite systems. There was no influence of host weight on parasite abundance and prevalence. Only one parasite species, M. monas, showed an influence of host sex on its abundance and prevalence. One pair of endoparasite species, O. lopesi and M. monas, showed an association in the infracommunities of B. ictericus. As in other parasite communities of Bufo species, the parasite community of B. ictericus was dominated by nematodes.

Spatial and seasonal changes in the diet of Oligosarcus hepsetus (Characiformes, Characidae) in a Brazilian reservoir.

Abstract: We assessed spatial and seasonal changes in the diet of Oligosarcus hepsetus in order to describe the strategy developed by this species that allows their very high abundance in Lajes reservoir, Rio de Janeiro, Brazil. Fish samplings were carried out using gill nets, deployed during ca. 12 and 24 hours, between April 2001 and May 2002. A total of 289 individuals were examined, of which 97 showed gut contents. We used the index of relative importance (IRI) to compare probable dietary shifts, and the frequency of occurrence (% OC) to analyze possible ontogenetic influences on feeding. O. hepsetus showed carnivorous habits, feeding preferably on fish and insects, the latter of which occurred in 71.0% of the guts presenting contents. O. hepsetus consumed different items along the three reservoir zones: insects (61.0% IRI) and Cichla monoculus (38.9% IRI) in the lower zone; Lepidoptera (57.0% IRI) in the middle zone; and C. monoculus (77.0% IRI) in the upper zone. Food items changed seasonally with C. monoculus predominating in autumn 2001, and Hymenoptera and Lepidoptera in the winter. In spring almost all food was Lepidoptera (99.8% IRI), while in the summer Hemiptera dominated in the diet. In autumn 2002 Hemiptera (97.0% IRI) was dominant, in significant contrast with the previous autumn. Individuals smaller than 190 mm SL fed heavily on insects, while fishes predominated in the diet of individuals larger than 190 mm SL. Shifts in prey-capture ability among length classes suggest decreasing intraspecific competition. A higher food plasticity seems to be the strategy employed by this opportunist species, which used food resources available in the reservoir.

Diversidade das assembléias de peixes nas quatro unidades geográficas do rio Paraíba do Sul

Abstract: Padroes na diversidade de peixes ao longo de quatro unidades geograficas (superior, medio-superior, medio-inferior e inferior) no rio Paraiba do Sul foram estudados com a finalidade de avaliar tendencias de variacoes espaciais (unidades geograficas) e temporais (periodos de cheia e seca). Vinte e cinco locais foram amostrados entre Dezembro de 2002 e Marco de 2003 (verao/cheia) e, entre Agosto e Novembro de 2003 (inverno/seca). Os peixes foram capturados com um esforco padronizado, utilizando redes de espera, tarrafas e peneiras. Um total de 81 especies foram registradas compreendendo 9 ordens, 29 familias e 55 generos. Characiformes apresentaram maior numero de especies (28) seguido de Siluriformes (23). Perciformes, principalmente Tilapia rendalli e Geophagus brasiliensis, e Cyprinodontiformes com destaque para Poecilia vivipara e Poecilia reticulata, foram os grupos numericamente mais abundantes, enquanto Siluriformes, principalmente Hypostomus luetkeni, e Perciformes com Geophagus brasiliensis apresentaram maior contribuicao em biomassa. Poecilia vivipara foi encontrada apenas no periodo de seca. Espacialmente, Hoplosternum littorale predominou no trecho medio-superior, Pimelodus fur, Hypostomus luetkeni, Glanidium albescens no trecho medio-inferior, e Loricariichtys spixii e Prochilodus lineatus no trecho inferior. O numero de especies e a riqueza de Margalef apresentaram um aumento do trecho superior para o inferior, principalmente durante o periodo de cheia. Especies que apresentaram ampla distribuicao ao longo do rio (G. brasiliensis, Oligosarcus hepsetus e P. reticulata) sao consideradas oportunistas por se aproveitarem dos recursos disponiveis em ambientes pobres, refletindo o estado de alteracoes do rio. Diferenciacoes na fisiografia ao longo da extensao longitudinal da bacia nao coincidiram com mudancas nas assembleias de peixes, sugerindo que fatores associados a alteracoes de habitats poderiam estar estruturando a comunidade de peixes a nivel local.

Phoretic Behaviour of Bromeliad Annelids ( Dero ) and Ostracods ( Elpidium ) using Frogs and Lizards as Dispersal Vectors

Abstract: The phoretic behaviour of ostracods (Elpidium bromeliarum) andannelids (Dero superterrenus) that inhabit tank bromeliads was studied. Our previous field observations had shown that bromeliad ostracods can be found attached to the skin of amphibians and reptiles that move among bromeliads, probably allowing the ostracods to colonise new tanks. In this paper, we present the first record of bromeliad annelids found attached to frogs moving among bromeliads in the field. We have also enlarged the database on bromeliad ostracods engaged in phoretic association with terrestrial vertebrates in three locations in southeastern Brazil. In our laboratory experiments bromeliad annelids show a strong significant tendency to climb onto papers that had been in contact with frog skin when compared with control papers, indicating a kind of chemically oriented behaviour. Bromeliad ostracods, on the other hand, attached themselves to treated and untreated papers with same frequency. When brought into contact with various species of frogs and lizards, the bromeliad annelids and ostracods both presented preference to attach themselves to frogs, but the annelids showed a stronger preference to attach to frogs and to avoid attachment to lizards. Another experiment demonstrated that bromeliad annelids are much more prone to dehydration than are ostracods. We suggest that the chemically oriented behaviour presented by bromeliad annelids toward frogs could diminish the risk of death by dehydration during the transport among bromeliads due to the moist characteristic of frog skins.

Padrões de precipitação e índices de erosividade para as chuvas de Seropédica e Nova Friburgo, RJ

Abstract: This work was carried out in order to calculate the different storm patterns, the rainfall erosivity index (EI30 and KE > 25) and adjust them with the monthly precipitation data for Seropedica and Nova Friburgo, in the State of Rio de Janeiro, Brazil. Based on the results obtained, it was concluded that the advanced pattern is the most common in these regions, corresponding to 61% in Seropedica and 58% in Nova Friburgo, of the total number of analyzed storms. The percentages of intermediate and delayed patterns were, respectively, 24 and 15%, for Seropedica and 24 and 18% for Nova Friburgo. The annual mean values of EI30 were 5,472.5 and 5,431.2 MJ mm ha-1 h-1 for Seropedica and Nova Friburgo, respectively. For the KE > 25 index, the annual mean values were 76.8 and 83.5 MJ ha-1 for Seropedica and Nova Friburgo, respectively.

Ecomorphological analysis of the masticatory apparatus in the seed-eating bats, genus Chiroderma (Chiroptera: Phyllostomidae)

Abstract: Recent data have shown that owing to their seed-predator capacity Chiroderma doriae and Chiroderma villosum trophically depart from all previously studied species within the canopy fruit-bat ensemble. In this paper, the hypothesis that morphological adaptations related to granivory have evolved in these bats is investigated and discussed. A canonical variate analysis was used to search for possible divergent trends between the masticatory apparatus of Chiroderma and other stenodermatines currently recognized in the same ensemble. A total of 142 specimens representative of eight species was included in the analysis. Species of Chiroderma can be discriminated from all other species in the sample based on the increased development of masseter-related variables (height of the anterior zygomatic arch, masseter moment arm, and masseter volume), which, in conjunction with other morphological characteristics (dentition and gape angle) discussed herein, corroborates the evolution of durophagy in this group. A complementary analysis based on a Mantel test revealed that the pattern of morphological differentiation that emerged from the canonical variate analysis does not agree with the one expected based solely on the phylogenetic relationships adopted for the canopy fruit-bats studied here. This result is consistent with the hypothesis that morphological adaptations related to granivory have evolved in Chiroderma.

Records of the rattlesnakes Crotalus durissus terrificus (Laurenti) (Serpentes, Viperidae) in the State of Rio de Janeiro, Brazil: a possible case of invasion facilitated by deforestation

Abstract: This paper documents the presence of rattlesnakes, as an invasive species, in several municipalities of the State of Rio de Janeiro. As previous registers indicate, these snakes probably invaded at least the municipality of Valenca carried by floodwaters between the decades of 1950 and 1960. In the new environment, along the margins of the Rio Preto, these snakes were able to establish new populations in deforested areas turned into cattle grazing. The presence of rattlesnake in the municipality of Barra do Pirai, a municipality that has no border with Rio Preto, however, indicates that these snakes dispersal into new areas may be facilitated by open areas, represented by pastures, created after deforestations.

Princípios de suplementação mineral em ruminantes

Abstract: Muito embora ja haja um solido conhecimento sobre as deficiencias minerais e suas consequencias para a saude e a produtividade dos bovinos no Brasil, paradoxalmente, essas informacoes, na maioria das vezes, nao vem sendo empregadas pelos profissionais das ciencias agrarias, que persistem em estimular o uso generalizado das misturas minerais ditas completas. A deficiencia de diversos minerais incluidos nestes suplementos, como ferro, cromo, enxofre, entre outros, nao ocorre sob condicoes naturais ou so existe em raras situacoes muito particulares. O presente topico aborda os equivocos e problemas relacionados com a suplementacao mineral tradicionalmente feita e discute os principais aspectos da denominada suplementacao mineral seletiva, que e fundamentada no fornecimento exclusivo do(s) mineral(is) deficiente(s) e na(s) quantidade(s) necessaria(s). Essa alternativa pode permitir uma economia expressiva (por vezes, de ate 700%) em relacao a suplementacao mineral comercial normalmente utilizada. De acordo com diversas estimativas, a suplementacao mineral pode constituir de 20 a 30 % dos custos totais de producao de gado de corte criados em pastagens, dai a importância de diminuir esses gastos. Um ensaio de reversao, no qual um grupo de animais recebe a mistura mineral comercial rotineiramente utilizada na propriedade e outro grupo, o suplemento seletivo, e a melhor opcao para discriminar os efeitos (positivos ou negativos) entre dois esquemas de suplementacao mineral para uma especifica fazenda. Por esse ensaio, investigam-se, racionalmente e por um longo periodo, os efeitos das duas opcoes de suplementacao mineral em teste, com minimo risco de perdas economicas.

A Triatoma maculata (Hemiptera, Reduviidae, Triatominae) population from Roraima, Amazon region, Brazil, has some bionomic characteristics of a potential Chagas disease vector.

Abstract: Even though Chagas disease is rare in the Brazilian Amazon, the conditions for the establishment of domiciliated cycles prevail in many areas where triatomines are of frequent occurrence. In Roraima, a previous serological and entomological survey in three agricultural settlements showed the existence of all transmission cycle elements, i.e., individuals infected by Trypanosoma cruzi, triatomine species previously found harboring T. cruzi in the broader Amazon region of neighboring countries and, domicile/ peridomicile conditions favorable to triatomine colonization. Triatoma maculata was the most frequent species, found in chicken houses in the peridomicile and sporadically within residences. Aiming to investigate the possibility of T. maculata to possess the potentiality to transmit T. cruzi in the area, bionomic characteristics were studied under laboratory conditions. These were feeding frequency, time for defecation after a blood meal, time elapsed in voluntary fasting pre- and pos-ecdysis, moulting time periods, pre-oviposition and oviposition periods and index of oviposition, incubation period, egg viability, longevity and mortality rate. Results show that the Passarao population of T. maculata should be considered a potential vector of T. cruzi since it shows a capacity to infest artificial ecotopes in the peridomicile, to carry out large number of meals during the nymphal cycle, to have a relatively short developmental cycle capable of producing 2.9 generations/year, to blood source eclecticism, to defecate immediately after the blood meal while still on the host and to the fact that has been previously found naturally infected by T.cruzi.

The influence of stress and anxiety on the response of non-surgical periodontal treatment.

Abstract: Aim: The aim of this study was to evaluate the influence of stress and anxiety on the response to non-surgical periodontal treatment (NPT) in patients with chronic periodontitis. Method: Sixty-six patients (mean age 46.1±8 years) were assigned to three groups: control group, probing pocket depth (PPD) leqslant R: less-than-or-eq, slant4 mm, n=20; T1, at least four sites with PPD geqslant R: gt-or-equal, slanted4 and leqslant R: less-than-or-eq, slant6 mm, n=26; and T2, at least four sites with PPD >6 mm, n=20. Stress, state anxiety (SA) and trait anxiety (TA) and plaque index (PI), gingival index, PPD and clinical attachment level (CAL) were recorded at baseline and 3 months after NPT. Results: TA scores were different among groups at baseline and after NPT. TA was related to periodontitis at baseline and after NPT. PI was associated with the SA at baseline. The reduction of frequency of CAL >6 mm was correlated with TA after adjusting for confounders. Stressed subjects did not show reduction of frequency of PPD >6 mm (T1), CAL 4–6 mm and CAL >6 mm (T2). Conclusions: The data suggest an influence of trait of anxiety and stress on the response to NPT.

Host population density as the major determinant of endoparasite species richness in floodplain fishes of the upper Paraná River, Brazil.

Abstract: A comparative analysis of parasite species richness was performed across 53 species of fish from the floodplain of the upper Parana River, Brazil. Values of catch per unit effort, CPUE (number of individuals of a given fish species captured per 1000 m(2) of net during 24 h) were used as a rough measure of population density for each fish species in order to test its influence on endoparasite species richness. The effects of several other host traits (body size, social behaviour, reproductive behaviour, spawning type, trophic category, feeding habits, relative position in the food web, preference for certain habitats and whether the fish species are native or exotic) on metazoan endoparasite species richness were also evaluated. The CPUE was the sole significant predictor of parasite species richness, whether controlling for the confounding influences of host phylogeny and sampling effort or not. The results suggest that in the floodplain of the upper Parana River (with homogeneous physical characteristics and occurrence of many flood pulses), population density of different host species might be the major determinant of their parasite species richness.

Plantio direto, adubação verde e suplementação com esterco de aves na produção orgânica de berinjela

Abstract: No-tillage systems were evaluated within an eggplant (Solanum melongena) organic management in Seropedica, Rio de Janeiro State. Crotalaria juncea and Pennisetum glaucum cv. BRS 1501 were used as pre- plantings besides fallowing, in comparison to conventional system (plowing). Simultaneously, three cropping managements were tested: eggplant single-cropping, intercropping with C. juncea, and intercropping with cowpea (Vigna unguiculata cv. Maua). No differences were found among planting systems concerning eggplant yield. Crotalaria juncea was more effective than Pennisetum glaucum and fallow for soil mulch. Intercropping with leguminous species did not decrease eggplant yield. In a second study no-tillage (on C. juncea and spontaneous weeds mulchs) and conventional plowing were compared. These treatments were combined with increasing levels of poultry manure (0, 100, 200, and 400 kg ha -1 of N). In terms of biomass input, C. juncea was again superior to spontaneous weeds. Eggplant responded to organic fertilization with maximum productivity (50.6 t ha -1 ) corresponding to the highest manure level applied, compared to 36.9 t ha -1 for control plots.

Prevalence of canine infection from endemic areas of American cutaneous leishmaniasis in Paracambi District, Rio de Janeiro State, between 1992 and 1993

Abstract: In the district of Paracambi, State of Rio de Janeiro an epidemiological survey for American tegumentary leishmaniasis in canine population was carried out in endemic localities. A total of 179 dogs was registered and 138 (77.1%) examined for their clinical aspects, development of delayed hypersensitivity (DHS) with Imunoleish® antigen and serological responses by indirect immunofluorescent reaction and enzyme-linked immunosorbent assay. In 9 (6.5%) dogs with active cutaneous lesions or suspect scars, 66.7% were caused by Leishmania sp; 44.4% produced infection in hamsters and showed growth in culture media, which was considered to be compatible with the species of Leishmania braziliensis complex. The molecular characterization (isoenzyme and KDNA restriction profiles) defined two strains with similar profiles for L. (Viannia) braziliensis. The prevalence of canine infection estimated by the cutaneous test, IFR and ELISA was 10.1%, 16.7% and 27.8%, respectively. The presence of clinical / sub-clinical form of ATL in canine population associated with human infections suggested that the dog can act as source of infection as well as for dissemination of the disease.

Effects of the size of sown seed on growth and yield of common bean cultivars of different seed sizes

Abstract: A field experiment was conducted to evaluate the effects of planting different sizes of seed of the same cultivar on biomass accumulation and grain yield of common bean (Phaseolus vulgaris L.) cultivars of different seed sizes. A 6 X 2 split-plot factorial design with four replicates was employed, with six bean cultivars as main plots and two seed sizes (small and large, the latter twice as heavy as the former) of the same cultivar as subplots. Eight weekly samplings of biomass were performed, and yield components were measured at maturity. Large seeds increased the leaf area index and the shoot and root biomass of bean cultivars, particularly at the beginning of the growth cycle, but they did not affect the pod biomass. Improved growth associated with the large seed was more intense for erect than for prostrate cultivars. Plants originating from small seed presented a higher relative growth rate and net assimilation rate than plants from large seed. Large seed did not affect grain yield, but reduced the number of seeds per pod, increased the 100-seed mass, and reduced the harvest index. The results indicate that sowing larger seeds of a bean cultivar can improve early-season plant growth, which might be advantageous for crop establishment in stress environments. However, some compensatory effect, associated with delayed leaf senescence, higher net assimilation rate, or greater number of seeds per pod, allows plants originating from small seed to achieve similar grain yield. Lack of consistent effects of the seed size on grain yield indicate that the extra costs of sowing only the largest seed would not be profitable, but large seed resulted in larger grains at harvest which usually attain better market price.

Aproveitamento da casca de melancia (Curcubita citrullus, Shrad ) na produção artesanal de doces alternativos*

Abstract: A melancia, botanicamente classificada como Curcubita citrullus , Shrad e originaria da India. Devido ao seu alto teor de agua, e ideal para ser consurnida no periodo de calor intenso, mais propriamente no verao. Por ser um fruto que produz consideravel quantidade de residuos nao comestiveis, o presente trabalho objetivou aproveitar as cascas da melancia para a producao artesanal de doces alternativos. Os resultados mostraram que os doces cremosos e em calda com e sem adicao de coco, obtiveram excelente aceitabilidade entre os consumidores adultos e criancas. PALAVRAS-CHAVE: Melancia; cascas; doces crernosos; doces em calda.

Step‐Gradient CCC Separation of Phenylpropanoid and Iridoid Glycosides from Roots of Stachytarpheta cayennensis (Rich.) Vahl

Abstract: Glycosylated phenylpropanoids and iridoids were isolated from the ethyl acetate extract from the roots of Stachytarpheta cayennensis by step gradient countercurrent chromatography (CCC). The chosen gradient utilized a stepwise increase of the butanol ratio in a normal phase separation, utilizing a biphasic EtOAc:BuOH:H2O solvent system, 1:X:1 v/v/v, in four steps: A−X=0.05, B−X=0.2, C−X=0.5 and D−X=1.0. The sequential increase of BuOH in the organic phase of the CCC solvent system, and wash‐off of stationary phase allowed the isolation of 4 compounds identified as martinoside, isoverbascoside, verbascoside, ipolamiide, and two more iridoid glycosides. These compounds covered a wide span of polarities.

Toxicidade de óleos essenciais de alho e casca de canela contra fungos do grupo Aspergillus flavus

Abstract: Considering the inhibitory property of essential plant oils on the mycelial development of fungi, and the importance of Aspergillus flavus-like fungi which may produce aflatoxins, this research was designed to evaluate the toxicity of essential oils against fungi belonging to the group A. flavus isolated from peanut crops. The toxicity of eight essential oils against two isolates of A. Flavuslike fungi was evaluated in comparison to the synthetic fungicide benomyl. The toxicity of Cinnamomum zeilanicum Breym. and Allium sativum L. essential oils was also evaluated against 37 fungal isolates for a period of 12 months. The highest inhibition of the mycelial development of A. flavus was obtained with cinnamon and garlic essential oils. The inhibitory effect on growth was variable according to the fungal isolate.

Produção de serapilheira e transferência de nutrientes em florestas secundárias localizadas na região de Pinheiral, RJ.

Abstract: An experiment was carried out to evaluate the contribution of the litter deposition under forest coverage in different stages of regeneration, initial secondary forest (ISF) and late secondary forest (LSF) in Pinheiral, RJ, in 1998. Litter deposition was measured in litter traps. The highest input of litter, 4.03 ton. ha -1 , was observed in LST, in winter. In both areas the highest input was verified in winter, and the leaves were the most important contributor. The chemical composition of litter did not show difference among the seasons.

Inheritance of root traits and phosphorus uptake in common bean (Phaseolus vulgaris L.) under limited soil phosphorus supply

Abstract: Summary Scarce information about genetic control of root traits in common bean (Phaseolus vulgaris L.) impedes a more effective exploitation of the reported variability for plant breeding. This work investigated the inheritance of traits related to the root system and P absorption of common bean grown under limited soil P supply. Two experiments were carried out, each one involving one family of crosses comprising six populations (two parental cultivars, F1, F2, and two backcrosses). One plant was grown per pot with 3 kg of soil (7 mg P kg −1 Mehlich-1) and harvested at pod setting. Root samples provided the root surface area and root length by digital image analysis. Considerable additive genotypic effects were detected in both experiments; additive × additive epistases were significant only in the second experiment, whereas dominance effects were seldom significant. Estimated broad-sense heritabilities were 0.55 and 0.51 for root area, 0.50 and 0.47 for root length, 0.51 and 0.61 for root mass, and 0.51 and 0.43 for the total P content, in the first and second experiments, respectively. High genotypic correlation between root mass and root area justifies screening genotypes based solely on root mass. Phenotypic and genotypic correlations between shoot mass and root mass, and shoot mass and total P content, were highly significant, indicating that direct selection for higher shoot growth of bean plants under limited soil P supply would result in increased root mass and P uptake. A scheme for root breeding in common bean towards improving P efficiency should include: matching cultivars with favourable alleles; advance until later generations without any selection; selection of resultant genotypes under low soil P supply via shoot growth; evaluation of promising lines for root growth and agronomic performance.

Response of Crotalaria juncea to nickel exposure

Abstract: A presenca de metais pesados no ambiente e atualmente, um dos principais problemas de contaminacao ambiental, uma vez que, os metais liberados no ambiente contaminam o solo e entram na cadeia alimentar atraves das plantas, causando efeitos toxicos a curto e a longo prazo aos animais e seres humanos. No caso do metal pesado Niquel (Ni), foi constatado que a sua presenca nas plantas pode diminuir o crescimento, reduzir a taxa de fotossintese e provocar alteracoes, tanto nas atividades enzimaticas quanto metabolicas.Pouca informacao esta disponivel na literatura, com referencia a resposta antioxidante das plantas a expressao a esse metal. Neste sentido, os objetivos deste trabalho foram realizar diferentes ensaios para avaliar o efeito fitotoxico do Ni em plântulas de C. juncea. Neste estudo foram analisados parâmetros bioquimicos relativos a atividade das enzimas antioxidantes, Catalase (CAT), Superoxido Dismutase (SOD) e Glutationa Redutase (GR). Constatou-se que, nao houve alteracao da atividade GR e CAT nas raizes. Entretanto, atividades destas enzimas apresentaram aumento significativo na parte aerea. O aumento na atividade da GR, na parte aerea, pode ser explicado pelo fato de ser o ciclo Halliwell-Asada o principal mecanismo que age na desintoxicacao de Especies Ativas de Oxigenio. Quanto a atividade da SOD, quando comparados ambos tecidos, foi constatado que na parte aerea foi pouco alterada, entretanto, a atividade da SOD foi estimulada nas raizes na presenca do Ni. Para aumentar a precisao dos resultados, quantificou-se pela tecnica de Fluorescencia de Raios X, a concentracao de NiCl2 e o seu efeito na absorcao de nutrientes nas plântulas de crotalaria. Nesta analise, observou-se o acumulo do metal nas raizes e baixa translocacao para a parte aerea. Tambem foi analisada a concentracao de Malonaldeido (MDA) na parte aerea de plântulas de C. juncea, sendo constatada, a ocorrencia de peroxidacao lipidica na presenca do Ni. Finalmente, determinou-se o efeito do Ni sobre as concentracoes de aminoacidos soluveis em raizes e na parte aerea, como estrategia desta planta para superar o efeito do Ni , nao tendo sido observadas variacoes significativas nas concentracoes dos mesmos com os diferentes tratamentos com Ni. Palavra?Chave: Aminoacidos, Atividade Enzimatica, Crotalaria, Fitotoxicidade, Niquel, Poluicao Ambiental Abstract