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Showing papers in "Scientia Agricola in 2007"


Journal ArticleDOI
TL;DR: In this paper, conservation tillage can partially reverse the process - they are aimed at increasing the input of organic matter to the soil and/or decreasing the rates at which soil organic matter decomposes.
Abstract: The intensive land use invariably has several negative effects on the environment and crop production if conservative practices are not adopted. Reduction in soil organic matter (SOM) quantity means gas emission (mainly CO2, CH4, N2O) to the atmosphere and increased global warming. Soil sustainability is also affected, since remaining SOM quality changes. Alterations can be verified, for example, by soil desegregation and changes in structure. The consequences are erosion, reduction in nutrient availability for the plants and lower water retention capacity. These and other factors reflect negatively on crop productivity and sustainability of the soil-plant-atmosphere system. Conversely, adoption of "best management practices", such as conservation tillage, can partly reverse the process - they are aimed at increasing the input of organic matter to the soil and/or decreasing the rates at which soil organic matter decomposes.

228 citations


Journal ArticleDOI
TL;DR: In this article, the most frequent threats and land use types in the vicinity of 81 Cerrado (tropical savanna type) fragments in the State of Sao Paulo, Brazil, were analyzed in order to verify if the frequency of every type of disturbance to the natural ecosystem depends on the neighboring land use.
Abstract: Patches of natural vegetation remaining in landscapes occupied by man are continuously under threat due to the edge effects and also to land use types around these remnants. The most frequent threats and land use types in the vicinity of 81 Cerrado (tropical savanna type) fragments in the State of Sao Paulo, Brazil, were analyzed in order to verify if the frequency of every type of disturbance to the natural ecosystem depends on the neighboring land use. The hypothesis of the study assumes that environmental threats are correlated with land use around protected areas. From the 81 areas, the most frequent human-induced land cover types around the Cerrado remnants were: pasture (recorded in 78% of the areas), sugarcane plantations (26%), roads (19%), annual crops and reforestation (14% each). The most frequent sources of threats were invasive grasses (35% of the areas partially or totally invaded) and cattle (observed in 32% of the areas), followed by deforestation (21%), and fire (21%). The chi-square analysis revealed that, with the exception of deforestation, which does not depend on land use, all other threats are influenced by the neighboring land use. The occurrence of invasive grasses and fires are strongly favored by the presence of roads and urban areas. Sugarcane, reforestation, and permanent crops were the less impacting land use types found in the study area, when only considering impact frequency. These land use types have fire and weed control, and also exclude cattle, indirectly protecting natural ecosystems.

192 citations


Journal ArticleDOI
TL;DR: The photochemical efficiency of PS2 (Fv/Fm) had a positive relationship with the photochemical quenching coefficient (qP), leaf area and chlorophyll content but had no relation with Fv'/Fm', Fo/fm, and qN.
Abstract: When plants are grown under saline conditions, photosynthetic activity decreases leading to reduced plant growth, leaf area, chlorophyll content and chlorophyll fluorescence. Seeds and seedlings of radish (Raphanus sativus L.) were grown in NaCl solutions under controlled greenhouse conditions. The NaCl concentrations in complete nutrient solutions were 0 (control), 4.7, 9.4 and 14.1 dS m-1. The salinity reduced germination percentage and also delayed the germination rate as the salt level increased. Lengths and fresh weights of root and shoot decreased with the increasing salt concentration. Furthermore, photochemical efficiency of PS2 (Fv/Fm), photochemical quenching coefficient (qP), non photochemical quenching coefficient (qN), leaf area and chlorophyll content (SPAD value) were also reduced (P < 0.001) by salt stress. In contrast, the Fo/Fm ratio increased with increasing salt concentration while salinity showed no effect on the efficiency of excitation captured by open PS2 (Fv'/Fm'), electron transport rate (ETR), and leaf water content. Linear regression shows that the photochemical efficiency of PS2 (Fv/Fm) had a positive relationship with the photochemical quenching coefficient (qP), leaf area and chlorophyll content but had no relation with Fv'/Fm', Fo/Fm, and qN.

168 citations


Journal ArticleDOI
Abstract: In many studies worldwide the use of treated sewage effluents (TSE) as water and nutrient sources in agricultural irrigation have been introduced as a viable alternative for wastewater destination in the environment. Considering agronomic and environmental aspects the objectives of this review were: (i) to present an overview of TSE irrigation on different agro-systems (annual crops, orchards, forests and forages); and (ii) to show the principal changes on chemical, physical and microbiological soil characteristics after TSE application. Various studies have revealed that the nutrient supply only by TSE irrigation was not sufficient to meet plant nutrient requirements resulting in yield decreases. The problem could be solved by an adapted effluent/fertilizer management. Moreover, TSE could generally substitute efficiently freshwater for irrigation. Regarding soil quality conditions, TSE irrigation affected mainly: (i) total soil carbon and nitrogen, and mineral nitrogen in soil solution; (ii) microbial activity, composition of microbial communities and their function; (iii) exchangeable calcium and magnesium; (iv) salinity, sodicity, clay dispersion and hydraulic conductivity. Other soil parameters considered in this review (e.g. heavy metals) did not present significant changes over short and medium terms. Due to the often observed accumulation of sodium and nitrogen losses (leaching, volatilization and denitrification) after TSE irrigation, the monitoring of these components is of crucial importance for a sustainable use. Finally, further studies on the technical-economical-environmental viability of TSE irrigation are required to establish reliable recommendations for TSE use particularly in Brazilian agro-systems.

128 citations


Journal ArticleDOI
TL;DR: In this paper, a cada tres meses, num total of 18 meses of armazenamento, foi avaliado o potencial fisiologico das sementes usando-se os testes of germinacao, envelhecimento acelerado e condutividade eletrica.
Abstract: Pesquisas com sementes de soja tem revelado que os resultados do teste de condutividade eletrica podem ser influenciados pela temperatura de armazenamento, sugerindo que a deterioracao das sementes em temperaturas baixas parece nao estar relacionada diretamente com a perda da integridade das membranas celulares. O presente estudo foi conduzido com o objetivo de verificar se a influencia de baixas temperaturas de armazenamento nos resultados da condutividade eletrica ocorre tambem para outra especie, sendo utilizadas para tanto, sementes de dois cultivares de ervilha. O efeito das seguintes temperaturas foi estudado: 10, 20, 25, 20/10 e 25/10oC. A cada tres meses, num total de 18 meses de armazenamento, foi avaliado o potencial fisiologico das sementes usando-se os testes de germinacao, envelhecimento acelerado e condutividade eletrica. O teste de condutividade eletrica nao se mostrou um bom indicador da intensidade do processo de deterioracao de sementes armazenadas a baixas temperaturas. A deterioracao das sementes a 10oC parece nao estar relacionada diretamente com a perda da integridade das membranas, possivelmente devido ao reparo ou a reorganizacao das mesmas durante o periodo de armazenamento nesta temperatura.

61 citations


Journal ArticleDOI
TL;DR: In this article, the most frequent rice herbicide in both rivers and in each year was clomazone, propanil and quinclorac, and at least one herbicide was detected in 41% of the samples from the Vacacai River and 33% from the VVM River.
Abstract: Irrigated rice production can involve environmental contamination with pesticides due to the proximity of the fields to rivers and to management problems. During three years (2000 to 2003) the rice herbicides clomazone, propanil and quinclorac were quantified in water during the rice growing season, in the Vacacai and Vacacai-Mirim Rivers, located in Rio Grande do Sul (RS) State, Brazil. Water samples were taken at several locations in each river, selected by their importance in terms of rice drainage area. The samples were analyzed by HPLC-UV. At least one herbicide was detected in 41% of the samples from the Vacacai River and 33% from the Vacacai-Mirim River. The most frequent herbicide in both rivers and in each year was clomazone. The amount of herbicides in the river water was dependent on the rainfall regime. River water contamination by rice herbicides is probably caused by the rice water management used in the fields. The maintenance of flooded areas makes herbicides prone to contaminate the environment. To reduce the environmental contamination risk it is necessary to adopt measures to avoid overflow of flooded rice fields, keeping paddy water in the field for time enough to reduce the herbicide concentration before its release and enhancing the quality of the levees to reduce the probability of paddy rice overflow.

61 citations


Journal ArticleDOI
TL;DR: Neotropical forests show high anuran species richness, but some Brazilian forest formations, like cerradao, semideciduous forests and restingas, remain poorly known, suggesting well-preserved ecosystems.
Abstract: Neotropical forests show high anuran species richness, but some Brazilian forest formations, like cerradao, semideciduous forests and restingas, remain poorly known. The composition of anuran species were determined for four forest sites belonging to different biomes in southeastern Brazil, based on two complementary techniques (visual encounter survey and survey on breeding sites), both applied simultaneously. A total of 60 anuran species belonging to eight families was recorded. Species richness and levels of endemism were higher in the Atlantic rainforest site. Sites located in the Cerrado domain were more alike than those located in the Atlantic Forest Domain. Similarity in anuran species composition was negatively correlated to the geographical distance among sites, which explains part of similarities in species composition. Factors affecting these occurrence patterns are discussed. One species (if its identity is confirmed) is considered Data Deficient by IUCN (The World Conservation Union), though it is not included in the Brazilian list of threatened amphibians. The presence of certain species with special habitats and microclimate requirements (bioindicators) suggests well-preserved ecosystems.

57 citations


Journal ArticleDOI
TL;DR: Present and future forest plant community biodiversity could be partially determined by the present structure of the canopy tree species community (filter effect), some theoretical and practical aftermaths are suggested.
Abstract: Each tropical and subtropical forest canopy species may create specific microsite conditions below its crown, which works as a filter for those species that attempt to regenerate below it. In function of the permeability or impermeability level, each canopy species could partially determine a plant community structure and composition beneath its crown projection. Therefore, present and future forest plant community biodiversity could be partially determined by the present structure of the canopy tree species community (filter effect). Some theoretical and practical aftermaths are suggested.

56 citations


Journal ArticleDOI
Abstract: Soil loss expectation and possible relationships among soil erosion, riparian vegetation and water quality were studied in the Sao Jose dos Dourados River basin, State of Sao Paulo, Brazil. Through Geographic Information System (GIS) resources and technology, Soil Loss Expectation (SLE) data obtained using the Universal Soil Loss Equation (USLE) model were analyzed. For the whole catchment area and for the 30 m buffer strips of the streams of 22 randomly selected catchments, the predominant land use and habitat quality were studied. Owing mainly to the high soil erodibility, the river basin is highly susceptible to erosive processes. Habitat quality analyses revealed that the superficial water from the catchments is not chemically impacted but suffers physical damage. A high chemical purity is observed since there are no urban areas along the catchments. The water is physically poor because of high rates of sediment delivery and the almost nonexistence of riparian vegetation.

53 citations


Journal ArticleDOI
TL;DR: Evaluated the biomass and diversity of earthworms in natural and reforested Araucaria plots, impacted or not by fire, and to identify the most efficient earthworm collection method, Formol was more efficient for collecting A. corticis than in the other areas.
Abstract: Araucaria angustifolia, also known as the Parana Pine is an endangered tree species in Brazil and little is known of the diversity of soil invertebrates inhabiting these forests. Therefore, the present study was set up to evaluate the biomass and diversity of earthworms in natural and reforested Araucaria plots, impacted or not by fire, and to identify the most efficient earthworm collection method. Four study areas included: native forest with Araucaria (NF); Araucaria reforestation (R); Araucaria reforestation submitted to an accidental fire (RF); and native grass pasture with native Araucaria and submitted to an intense accidental fire (NPF). Five soil samples containing the earthworm community were taken in a 0.3 ha area in each of the forest sites, close to five Araucaria trees selected at random. Three collection methods were tested: application of dilute Formol (0.5%) to the soil surface, handsorting of small (25 ´ 25 cm) or large (40´ 40 cm) monoliths. Five earthworm species were found: the native Glossoscolex sp.1, Glossoscolex sp.2, Glossoscolex bondari and Urobenus brasiliensis (Glossoscolecidae), and the exotic Amynthas corticis (Megascolecidae). Formol was more efficient for collecting A. corticis, found in much higher abundance and biomass in NF than in the other areas. Larger handsorted samples were more efficient for capturing Glossoscolex species, mainly present in RF and NPF. For adequate characterization of earthworm abundance and biomass in these Araucaria forests, both the Formol and the larger monolith methods are recommended.

47 citations


Journal ArticleDOI
TL;DR: The traditional agriculturists of Vale do Ribeira maintain a high morphological diversity for sweet potato within their households, which can be assumed to be produced by the outcrossing mating system of this species and somatic mutation events, as well as the exchange system at local and regional levels.
Abstract: The phenotypic diversity of sweet potato (Ipomoea batatas) landraces was assessed using morphological traits, verifying how this diversity is distributed among the households and settlements of the Vale do Ribeira, Brazil. A total of 74 accessions, involving 53 landraces, collected from 30 households distributed among 18 settlements that practice traditional agriculture in the municipalities of Iguape, Ilha Comprida, and Cananeia, as well as four commercial varieties acquired in markets of Iguape and Piracicaba, were evaluated under an ex situ experimental condition in Piracicaba, SP, Brazil. Nine phenological and floral descriptors, nine morphological vegetative aerial descriptors and five storage root traits were recorded. The 14 aerial vegetative and root descriptors were evaluated as binary data, totaling 74 attributes. Cluster analyses were made using the Jaccard similarity index and the UPGMA (unweighted pair group method with arithmetic mean) agglomerative method. Binary data was also submitted to a variance analysis (AMOVA). No defined groups were observed, indicating that the diversity of the landraces is not structured in space, but considerable morphological variation was found in this area (Jaccard similarity index varying from 0.12 to 1.0). Most of the variability occurred within households (64.4%), followed by the distribution among households within settlements (27.1%) and among settlements (8.4%). Thus, the traditional agriculturists of Vale do Ribeira maintain a high morphological diversity for sweet potato within their households, which can be assumed to be produced by the outcrossing mating system of this species and somatic mutation events, as well as the exchange system at local and regional levels.

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the "Zarco HS" yellow pepper at various levels of ripeness taking into account its physico-chemical properties (titratable acidity, pH, total soluble solids, water content, and ascorbic acid), in order to understand this behavior during the ripening process.
Abstract: The bell pepper presents alterations in its composition and its properties with the process of senescence during ripening. These composition and textual factors are part of the quality of the fruit and therefore of the selection. This permits the correct knowledge of the factors necessary for post-harvest measures, so that they can be adequately applied. The aim of this study is to analyze the 'Zarco HS' yellow pepper at various levels of ripeness taking into account its physico-chemical properties (titratable acidity, pH, total soluble solids, water content, and ascorbic acid), in order to understand this behavior during the ripening process. Bell peppers were separated based on their yellow percentage, which varied from 0% to 100%, and for each percentage five fruits were chosen as replicates. They were compared to 0%, 25%, 50%, 75% and 100% levels of ripening, due to the difficulty of the methodology in identifying the smaller differences between coloring. The 'Zarco HS' yellow bell pepper presents greater levels of soluble solids and lower levels of malic acid as the percentage of external yellow coloring increases. The yellow bell peppers, especially when totally yellow, represent an important source of vitamin C.

Journal ArticleDOI
TL;DR: In this paper, a map of the cobertura dominant do solo in a set of bacias hidrograficas in the state of Brazil is presented, where the authors investigate the relationship between coberture do solo and the declividade of the terreno.
Abstract: Informacoes sobre mudancas no uso e cobertura do solo sao fundamentais para varios propositos sociais, economicos e ambientais. O principal objetivo deste estudo foi elaborar mapas de cobertura do solo usando imagens digitais obtidas por satelite no ano de 1997 nas seguintes bacias hidrograficas do Estado de Sao Paulo: Piracicaba, Moji-Guacu, Alto Paranapanema, Turvo Aguapei, Peixe, and Sao Jose dos Dourados. Adicionalmente, a relacao entre a cobertura do solo e a declividade do terreno tambem foram investigadas. Um segundo objetivo foi estimar a proporcao relativa de vegetacao riparia considerando-se uma faixa de 30 metros em relacao as margens dos corpos d'agua. As tres principais questoes cientificas deste artigo foram: i) Qual e a cobertura dominante do solo nas bacias hidrograficas abordadas? ii) As vegetacoes riparias encontram-se bem preservadas riparia nas faixas dos 30 metros? Em caso negativo, iii) Qual e a cobertura do solo dominante nessas areas? A cobertura do solo predominante nas bacias hidrograficas sao as pastagens, ocorrendo em quase 50% de toda a area investigada. Seguem-se as plantacoes de cana-de-acucar (14%) como sendo as coberturas do solo mais importantes. Aproximadamente metade da area das sete bacias foi considerada plana (40%) ou suavemente ondulada (10%). A area riparia considerando-se uma largura de 30 metros em relacao as margens dos corpos d'agua ocupa uma area aproximada de 6.200 km2. Deste total, somente 25% encontram-se bem preservadas. Dentre as culturas, as pastagens ocupam a maior area na zona riparia. Nas bacias dos rios Moji-Guacu e Piracicaba a cana-de-acucar e a principal cultura invasora da zona riparia.

Journal ArticleDOI
TL;DR: Canonical discriminant analysis (CDA) indicated Shannon's diversity index as the ecological attribute that contributed the most to distinguish between forest ecosystems, with higher value of H in FN in relation to R.
Abstract: O pinheiro brasileiro, Araucaria angustifolia (Bert.) O. Ktze e uma especie arborea ameacada de extincao, quase exterminada pela exploracao descontrolada de madeira. Essa especie demonstra alta dependencia de fungos micorrizicos arbusculares (FMA), de grande importância para a estabilidade do ecossistema e manutencao da biodiversidade. Avaliou-se a colonizacao radicular, a densidade e a diversidade de esporos de FMA em duas florestas com araucaria, distintas no processo sucessional, em duas epocas de amostragem: maio e outubro. As florestas, localizadas no Parque Estadual Turistico do Alto do Ribeira (PETAR), correspondem a 1) Floresta Ombrofila Mista nativa (FN), em estagio climax, sem sinais de interferencia antropica, e a 2) floresta de araucaria plantada em 1987 (R), submetida a pastoreio. Foram avaliados: colonizacao radicular, numero de esporos e riqueza de especies de FMA e calculados os indices de dominância de Simpson (Is) e de diversidade de Shannon (H). A colonizacao radicular nao diferiu entre as duas comunidades na primeira amostragem (maio). Na segunda amostragem (outubro), houve maior colonizacao radicular na floresta nativa do que na floresta plantada e a colonizacao radicular foi mais intensa em comparacao com as coletas de maio. No total, foram encontradas 27 especies de FMA, com maior numero de esporos em FN em relacao a R. A analise canonica discriminante (ACD) indicou que o indice de diversidade de Shannon foi o atributo ecologico que mais contribuiu para distinguir os dois ecossistemas florestais, com altos valores de H para FN em relacao a R. ACD mostrou ser importante ferramenta para o estudo dos atributos ecologicos.

Journal ArticleDOI
TL;DR: To better understand the differences in feeding behavior of adults and nymphs of this pest and the subsequent disorders that arise, stylet penetration through fixation, staining and sectioning was investigated.
Abstract: The sugarcane spittlebug Mahanarva fimbriolata (Stal) (Hemiptera: Cercopidae) is a pest of mechanically-harvested sugarcane in Brazil, when trash burning is not performed. To better understand the differences in feeding behavior of adults and nymphs of this pest and the subsequent disorders that arise, stylet penetration through fixation, staining and sectioning was investigated. Nymphs cause a "physiological disorder" damaging the tracheary system of the roots, slowing or preventing water and nutrient flow, with phloem and xylem dehydration. Nymphs insert their stylets through the epidermis, crossing the cortex, endodermis and pericycle before reaching the vascular cylinder, where they feed in the sieve-tube elements of the primary phloem. In contrast, adults feed on leaves, causing "sugarcane burn", and reducing plant photosynthesis. Adults introduce the stylets into the leaf blade through the stomata, passing the chlorophyll-bearing parenchyma cells before reaching the metaxylem in the vascular bundles.

Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive evaluation, on a yearly basis, of carbon, nitrogen and major ion fluxes in streams crossing areas under different land use (natural vegetation, sugar cane and eucalyptus) in a savanna region of SE Brazil.
Abstract: Several studies in tropical watersheds have evaluated the impact of urbanization and agricultural practices on water quality. In Brazil, savannas (known regionally as Cerrados) represent 23% of the country's surface, representing an important share to the national primary growth product, especially due to intense agriculture. The purpose of this study is to present a comprehensive evaluation, on a yearly basis, of carbon, nitrogen and major ion fluxes in streams crossing areas under different land use (natural vegetation, sugar cane and eucalyptus) in a savanna region of SE Brazil. Eucalyptus and sugar cane alter the transport of the investigated elements in small watersheds. The highest concentration of all parameters (abiotic parameters, ions, dissolved organic carbon DOC - and dissolved inorganic carbon - DIC) were found in Sugar Cane Watersheds (SCW). The observed concentrations of major cations in Eucalyptus Watersheds (EW) (Mg, Ca, K, Na), as well as DIN and DOC, were found frequently to be intermediate values between those of Savanna Watersheds (SW) and SCW, suggesting a moderate impact of eucalyptus plantations on the streamwater. Same trends were found in relation to ion and nutrient fluxes, where the higher values corresponded to SCW. It is suggested that sugar cane plantations might be playing an important role in altering the chemistry of water bodies.

Journal ArticleDOI
TL;DR: In this article, an experimento in Latossolo Vermelho alico textura argilosa em casa-de-vegetacao foi conduzido to evaluate the efeito da reacao do solo sobre a disponibilidade de silicio for a cultura do arroz.
Abstract: A solubilidade e disponibilidade de silicio podem ser influenciadas pela reacao do solo. Com o objetivo de estudar o efeito da reacao do solo sobre a disponibilidade de silicio para a cultura do arroz, foi conduzido experimento em Latossolo Vermelho alico textura argilosa em casa-de-vegetacao. O experimento foi conduzido em fatorial 4 x 4, delineamento em blocos inteiramente casualizados e quatro repeticoes. Quatro materiais (calcario, silicato de calcio e magnesio, acido silicico purissimo e wollastonita) foram aplicados em doses equivalentes a 0, 2500, 5000, 7500 mg por vaso de 5 kg. Apos 60 dias, foram avaliadas producao de materia seca, absorcao de silicio da parte aerea do arroz, pHCaCl2, silicio extraido em acido acetico (0,5 mol L-1) e CaCl2 (0,01 mol L-1) no solo. Os materiais aumentaram o pH do solo com as doses, exceto o acido silicico. O silicio soluvel em acido acetico foi crescente com as doses dos materiais. Para o CaCl2, apenas houve aumento de silicio soluvel no solo com as doses de wollastonita e silicato de calcio e magnesio, concordando com seu teor total. A absorcao de silicio pela parte aerea do arroz foi linearmente crescente com as doses da wollastonita, seguida do silicato de calcio e magnesio, acido silicico e calcario. O aumento do pH do solo com calcario nao foi suficiente para fornecer silicio ao arroz. O silicio extraido com CaCl2 0,01 mol L-1 apresentou maior correlacao com a absorcao de silicio pelas plantas. Mais estudos sao necessarios em condicoes de campo e outros solos para corroborar os resultados apresentados.

Journal ArticleDOI
TL;DR: In this paper, the effects of EDTA-chelating agent for Pb-uptake by maize were evaluated, i.e., the maize as a Pbaccumulator plant, ii.
Abstract: One of the most viable strategies to restore metal contaminated soils is the introduction of plants specialized in their accumulation or able to tolerate very high metal concentrations. This research evaluated: i. the maize as a Pb-accumulator plant; ii. the effects of EDTA-chelating agent for Pb-uptake by maize; iii. amending effect of EDTA on the soil Pb-availability using different extracts. Treatments consisted of Pb rates (100; 200; 350; 1,200 and 2,400 mg kg -1 ) applied to a Rhodic Hapludox in the form of Pb 3 (NO) 2 with (0.5 g kg -1 ) and without EDTA. Lead concentrations were determined in maize plant shoots. Soil available Pb was obtained using DTPA, Mehlich-3 and saturation solutions methods. Ionic speciation in the soil solution was performed using the software Visual-Minteq. Although a low t value was found (t 1,500 mg kg -1 of Pb) in maize shoots regardless of EDTA addition. Maize plants treated with EDTA had lower dry matter yield, mainly due to toxic levels of Fe and Al of the Oxisol. All extracting solutions were effective to determine available Pb in soil samples, but the saturation extract is a more difficult and time consuming procedure. At low and medium Pb levels, the plants grew less on EDTA, therefore the phytoextration process was less efficient. The addition of EDTA to the soil is not recommended with the purpose of increasing Pb

Journal ArticleDOI
TL;DR: Both molecular and morpho-agronomical data sets were equally effective to quantify and organize the genetic diversity of common bean accessions and may be useful to direct crosses and for the proper organization of the IAC germplasm bank.
Abstract: Germplasm banks store genotype samples, improved varieties, landraces and wild species, all generically denominated accessions. The importance of characterizing germplasm banks is based on the identification and knowledge of relevant traits for genetic improvement and ex situ germplasm conservation. Thus, the present study had as aim the evaluation of the genetic diversity among 220 accessions of a Brazilian common bean germplasm bank of the "Instituto Agronomico de Campinas" (IAC) by means of 23 morpho-agronomical descriptors and 19 RAPD loci. These accessions correspond to genotypes from the Andean and Middle American gene pool as well as from cultivars derived from common bean improvement programs. The Middle American accessions and the improved cultivars were clustered into one group, distinct from the one formed by the Andean accessions. In relation to the molecular data, 47% of the genetic similarity was detected among the Middle American accessions, and similar results were observed for the improved cultivars (50%). The Andean accessions revealed 60% of genetic similarity. The cluster constituted by the improved cultivars and the Middle American genotypes differed, basically, in tegument color. Both molecular and morpho-agronomical data sets were equally effective to quantify and organize the genetic diversity of common bean accessions. This information may be useful to direct crosses and for the proper organization of the IAC germplasm bank.

Journal ArticleDOI
TL;DR: The authors defendo que this paradoxo, numa perspectiva cientifica, tenha dois principios centrais nos quais cientistas talvez devessem se concentrar.
Abstract: A tematica da biodiversidade no Brasil alcancou um ponto critico onde, por um lado, a ciencia da biodiversidade aumenta em quantidade e em qualidade, enquanto que por outro, a destruicao de habitats nos grandes biomas brasileiros se mantem em taxas alarmantes. Eu defendo que este paradoxo, numa perspectiva cientifica, tenha dois principios centrais nos quais cientistas talvez devessem se concentrar. Primeiramente, embora as ciencias relacionadas a biodiversidade no Brasil sejam de alto padrao se comparadas com o que e produzido no resto do mundo, o pais ainda nao detem a ponta do conhecimento em nenhuma destas ciencias. E segundo lugar, a riqueza de informacoes produzida por fortes programas de pesquisa - como o Biota/Fapesp, ao qual este numero especial de Scientia Agricola e dedicado - esta apenas comecando a auxiliar tomadores-de-decisao a aumentar a precisao e a qualidade das decisoes referentes ao meio ambiente, mas ainda ha muito a ser feito a este respeito. Portanto, eu discuto alguns dos topicos acerca da biodiversidade que permanecem controvertidos e demandam rapido crescimento cientifico. Eu proponho que atacando estes temas o Brasil talvez possa vir a alcancar a ponta do conhecimento em medio prazo. Em seguida, discuto como podem ser aprimoradas as vias de comunicacao entre cientistas e tomadores-de-decisao e o publico em geral, enfatizando como um forte programa educacional - que cubra do jardim de infância a pos-graduacao - sera imprescindivel para solucionar os dois problemas acima e definitivamente romper com o paradoxo conhecimento da biodiversidade vs. destruicao da biodiversidade.

Journal ArticleDOI
TL;DR: Bt maize hybrids expressing insecticide proteins Cry1A(b) and VIP 3A do not cause reduction of the main maize dweeling predators and parasitoids.
Abstract: Although not yet available for cultivation in Brazil, the effect of Bt maize hybrids on natural enemies and soil dwelling arthropods should be assessed prior to its release to growers. Trials were carried out during one growing season in two different locations with the genetically modified maize hybrids 7590-Bt11 and Avant-ICP4, comparing with their respective non-Bt isogenic hybrids. Arthropods were evaluated through direct observation on plants and pitfall traps. In general, no differences were observed between populations of earwig (Dermaptera: Forficulidae), lady beetles (Coleptera: Coccinellidae), minute pirate bug (Coleoptera: Anthocoridae), ground beetles (Carabidae), tiger beetles (Cicindelidae), and spiders (Araneae). There was no difference in egg parasitism of Helicoverpa zea (Boddie) by Trichogramma sp. (Hymenoptera: Trichogrammatidae). Thus, Bt maize hybrids expressing insecticide proteins Cry1A(b) and VIP 3A do not cause reduction of the main maize dweeling predators and parasitoids.

Journal ArticleDOI
TL;DR: In this article, the authors compared soil micro and macromorphologic attributes to soil water retention on a toposequence under native savanna woodland (cerradao) in a permanent plot of 320 m ´ 320 m installed in Assis, Brazil.
Abstract: The limiting factors of the Brazilian savanna physical environment have been largely discussed. Soil morphology is fundamental to understand the behavior of soil water flow, soil physical properties and soil-landscape relationships. The aim of this study is to relate soil micro and macromorphologic attributes to soil water retention on a toposequence under native savanna woodland (cerradao) in a permanent plot of 320 m ´ 320 m installed in Assis, SP, Brazil. Samples collected at five points within the toposequence were used to determine the soil macroporosity by means of image analyses, estimated total porosity, chemical analysis, particle size distribution analysis and soil water retention. From the summit down to the footslope, the soils were classified as Rhodic Haplustox, Typic Haplustox and Epiaquic Haplustult, presenting a gradual color transition and a sandy loam texture. In the surface horizons, the higher organic matter content and the high total macroporosity determined a lower soil bulk density and lower water retention. In the Oxisols, the high soil macroporosity results from the packing of microaggregates in the oxic horizon. In the Ultisol, the lower total porosity in the deeper horizons resulted in a higher water retention and an imperfect water drainage. The water retention conditions on the slope influenced the morphological differences in soil color and structure. The low water retention on the surface and oxic horizons, conditioned by the high total macroporosity, is one of the factors that may define the vegetal pattern of the savanna woodland within the permanent plot.

Journal ArticleDOI
TL;DR: In this article, the authors compared the results of the Walkley-Black and dry combustion methods with corresponding results obtained through the dry combustion method (Elementar Vario EL analyzer), using samples of ten soil layers down to the depth of 1075 cm of a kaolinitic Typic Paleudult (220-418 g clay kg -1 along the profile) subjected to no-till cropping systems (fallow bare soil, pigeon pea (Cajanus cajan L Millsp) plus maize, and lablab (Lablab purpure
Abstract: Organic carbon (C) concentration evaluated by the Walkley-Black method, and total nitrogen (N) concentration determined by Kjeldahl method, were compared with corresponding results of C and N concentrations obtained through the dry combustion method (Elementar Vario EL analyzer), using samples of ten soil layers down to the depth of 1075 cm of a kaolinitic Typic Paleudult (220-418 g clay kg -1 along the profile) subjected to no-till cropping systems (fallow bare soil, pigeon pea (Cajanus cajan L Millsp) plus maize, and lablab (Lablab purpureum L Sweet) plus maize) A close correlation (R 2 ≥ 096) was observed between the C results of the Walkley-Black and dry combustion methods, but a correction was suggested to be applied to C results of Walkley-Black (C = 105C WBlack + 047) A close correlation (R 2 ≥ 096) was also found between results of Kjeldahl-N and dry combustion-N, but no correction was necessary to be applied The relationships between results of Walkley-Black and dry combustion and between results of Kjeldahl and dry combustion did not change among soil samples from different management systems, in disagreement to findings of a previous study where results of analytical C recovery were influenced by samples from different managements, supposedly because changes in lability or recalcitrance of organic matter might have affected the wet combustion reactions A poor correlation (R 2 = 042) was found between the C:N ratios based on Walkley-Black and Kjeldahl analysis and the C:N ratios based on dry combustion analysis The methods for C and N determination

Journal ArticleDOI
TL;DR: In this article, a tamanho de amostra adequado for the comprimento of espiga, diâmetro de espiga e de sabugo, o peso da espiga and the number of fileiras de graos por espiga.
Abstract: O uso dos tamanhos de amostras adequados nas unidades experimentais melhora a eficiencia da pesquisa. Foi conduzido um experimento no ano agricola 2004/2005 em Santa Maria, Rio Grande do Sul, com o objetivo de estimar o tamanho de amostra para o comprimento de espiga, o diâmetro de espiga e de sabugo, o peso da espiga, dos graos por espiga, do sabugo e de 100 graos, o numero de fileiras de graos por espiga, o numero de graos por espiga e o comprimento dos graos de dois hibridos simples (P30F33 e P Flex), dois hibridos triplos (AG8021 e DG501) e dois hibridos duplos (AG2060 e DKB701) de milho. Para uma precisao de 5% (D5), caracteristicas de peso (peso de espiga despalhada, de graos, de sabugo e de 100 graos) podem ser amostradas com 21 espigas, caracteristicas de tamanho (comprimento de espiga e de grao, diâmetro de espiga e de sabugo) com oito espigas, e dados de contagem (numero de graos e de fileiras) com 13 espigas. O tamanho de amostra e variavel em funcao da caracteristica da espiga e do tipo de hibrido: simples, triplo ou duplo. A variabilidade genetica existente entre os hibridos de milho, na forma crescente: simples, triplo e duplo, nao reflete na mesma ordem no tamanho de amostra de caracteres da espiga.

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TL;DR: In this paper, the capacitance probe (Diviner 2000) was calibrated for a Rhodic Paleudult from the Piaui State, Brazil, where six access tubes were installed in a 5 × 2 m grid arrangement.
Abstract: The use of capacitance sensors is one of the methods used to quantitatively measuresoil water contents (θ, m 3 m -3 ). Sensors provide readings at desired depths and time intervals. Acapacitance probe (Diviner 2000) was calibrated for a Rhodic Paleudult from the Piaui State, Brazil. Sixaccess tubes were installed in a 5 × 2 m grid arrangement. Three moisture levels (saturated, moist anddry) were used in two replications. Probe readings and soil samplings to determine θ were made at 0.1m depth intervals down to a depth of 1.0 m. A power calibration equation was developed for eachdepth as well as for the entire soil profile (Root Mean Square Error = 0.014, R 2 = 0.93) for a θ range of0.068 to 0.264 m 3 m -3 . A separate calibration for each depth improves the correlation coefficient andminimizes RMSE. Site-specific calibration improves the accuracy for soil water monitoring.Key words: FDR probe, sensor, irrigation, soil water content CALIBRACAO DE UMA SONDA DE CAPACITÂNCIAEM UM ARGISSOLO

Journal ArticleDOI
TL;DR: A presenca de arvores em pastagens contribuiu para C mais estavel nos perfis dos solos e o mais baixo FSA e a maior CAFS indicaram os grandes beneficios ambientais fornecidos pelos sistemas de silvopastagem comparados com as Pastagens com poucas arvore em condicoes ecologicas similares.
Abstract: Nossa hipotese e de que devido a habilidade das arvores sequestrarem carbono (C) no perfil profundo do solo e remover o excesso de nutrientes dos solos, o sistema de silvopastagem agroflorestal poderia melhorar a qualidade ambiental de terras agricultaveis. Para testar esta hipotese, dois grupos de experimentos foram conduzidos em duas ordens de solos na Florida, Espodossolos e Ultissolos, com dois objetivos principais: i) determinar a acumulacao de C do solo e investigar as fontes de C para as plantas nas fracoes dos solos, e ii) quantificar o fosforo soluvel em agua (FSA) e estimar a capacidade de armazenamento de fosforo no solo (CAFS). O C total em ambos os solos foi maior sob o sistema de silvopastagem do que sob pastagens com menos arvores, particularmente nas profundidades mais baixas. A analise por assinatura de isotopo estavel sugeriu que as plantas C3 (neste caso, slash pine, Pinis elliotti) contribuiram mais para a fracao estavel do carbono do que plantas C4 (neste caso, bahiagrass, Paspalum notatum) nas profundidades dos solos acima de 1 m. O FSA foi consistentemente maior em pastagens com poucas arvores, enquanto que a CAFS foi mais baixa neste sistema, sugerindo a grande probabilidade do fosforo ser mais facilmente movido do solo sob pastagens com poucas arvores do que nos sob silvopastagem. Deste modo, a presenca de arvores em pastagens contribuiu para C mais estavel nos perfis dos solos e o mais baixo FSA e a maior CAFS indicaram os grandes beneficios ambientais fornecidos pelos sistemas de silvopastagem comparados com as pastagens com poucas arvores em condicoes ecologicas similares.

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TL;DR: Two fruit colour varieties of E. brasiliensis can be considered as two distinct chemotypes, since the sesquiterpene pathway is more operant in the purple variety than in the yellow one, in which monoterpenes are mainly accumulated.
Abstract: Eugenia brasiliensis Lam. is a variable species concerning fruit colour, with three recognized varieties. However, the definition of varieties is not easy for Myrtaceae species and not widely accepted. Two fruit colour varieties (purple and yellow) of E. brasiliensis had their essential oil composition analysed in order to give support to the existence of varieties for this species. Although, the major components in the leaf oil are the same monoterpenes for both varieties, α-pinene, β-pinene and 1,8-cineol, the purple fruit variety accumulates more oxygenated sesquiterpenes (33.9%) than the one with yellow fruits (3.8%). The major differences occurred in purple fruits that present as major components caryophyllene oxide (22.2%) and α-cadinol (10.4%), not found in the leaf oil, and the yellow fruit oil presented a similar composition as observed for the leaves. These fruit colour varieties of E. brasilensis can be considered as two distinct chemotypes, since the sesquiterpene pathway is more operant in the purple variety than in the yellow one, in which monoterpenes are mainly accumulated.

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TL;DR: TEM was found to be closely related to root colonization and mycorrhizal effectiveness and mutually afected by P availability, and more AMF species should be assessed in order to attest whether P levels affect the external mycelium differentially among them.
Abstract: Despite the awareness that high phosphorus (P) availability decreases the mycorrhizal root colonization in higher plants, the effects on the external mycelium are contradicting. The aim of this work was to assess the external mycelium of the arbuscular mycorrhizal fungi (AMF) Glomus intraradices and Gigaspora rosea, associated to soybean under increasing P levels (0, 25, 50, 100 and 200 mg kg-1). The tested hypotheses were: a) the amount of external mycelium depends on the fungal species; b) the P levels affect diferentially each mycorrhizal species; c) the mycorrhizal effectiveness depends on the amount of external mycelium. Mycorrhizal stimulus on plant biomass occurred at P levels of 0, 25 and 200 mg kg-1. Mycorrhizal root colonization and total external mycelium (TEM) decreased with increasing P levels. At zero P level, G. rosea produced less TEM than G. intraradices, which may be related to the lower mycorrhizal effectiveness for G. rosea. Both AMF increased the active external mycelium along P levels, but this increase was not related with symbiotic effectiveness. TEM was found to be closely related to root colonization and mycorrhizal effectiveness. The root colonization and TEM are mutually afected by P availability. Althoug G. intraradices produced more TEM than G. rosea along the P levels, they seemed to affect similarly the TEM for both AMF. More AMF species should be assessed in order to attest whether P levels affect the external mycelium differentially among them.

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TL;DR: In this article, the authors identify that extensive areas, usually covered by pastures, will remain bare, intensively tilled, and without complementary mechanical soil control practices, and the precise assessment of these impacts, caused by the estimated 10 million hectares of the yearly replanted pastures is unknown.
Abstract: Pastures are normally associated with minor erosion problems because of their efficient soil cover. Soil cover is without doubt the most effective inter-rill and rill erosion control practice. However, considering the frequency at which pastures are replanted in Brazil and their enormous territorial extension (178 million hectares) we identify that extensive areas, usually covered by pastures, will remain bare, intensively tilled, and without complementary mechanical soil control practices. The pasture area is equivalent to that occupied by most important Brazilian annual crops (corn or soybeans), that are usually cultivated under no-tillage or supported by governmental soil conservation programs. The precise assessment of these impacts, caused by the estimated 10 million hectares of the yearly replanted pastures is unknown, and there is lack of scientific knowledge to suggest an adequate solution. This is, probably, the greatest challenge of Brazilian soil conservation and for an adequate resolution, will require a joint effort of researchers, technicians, educators and stakeholders.

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TL;DR: In this article, the effects of both chemical amendments (calcium silicate and brewery sludge), and phytoremediation using the grass Brachiaria decumbens, on an industrial residue contaminated with Zn and Cd (industrial residue).
Abstract: Phytostabilisation of a contaminated soil with heavy metals is considered a very appropriate technology to reduce erosion and dispersion of contaminants. A greenhouse study was conducted to evaluate the effects of both chemical amendments (calcium silicate and brewery sludge), and phytoremediation using the grass Brachiaria decumbens, on an industrial residue contaminated with Zn and Cd (industrial residue). Industrial residue samples placed into 30 L containers were amended with 20% brewery sludge, calcium silicate (2%, 3%), and 20% of brewery sludge + calcium silicate (2.5%, 4%), and were compared to the control treatment (non-amended residue). After pH stabilization, B. decumbens plants were grown on all treatments in order to evaluate the ability of the species to tolerate high Zn and Cd concentrations from the residue. Samples were collected twice, at planting and harvesting, for pH determination and simple extractions with water, sodium nitrate, acetic acid and DTPA. Differences in Zn and Cd concentrations in extracts allowed to estimate the concentrations of these elements in the most likely chemical forms they are found in the residue. Alkaline and organic industrial amendments reduced Zn and Cd percentages, both in the soluble and exchangeable fractions, as well as caused the predominance of Zn and Cd in the most stable chemical fractions, such as complexed and precipitated compounds. B. decumbens was tolerant to Zn and Cd from the industrial residue after addition of the amendments.