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Variabilidade de nutrientes em plantas de milho cultivado em talhão manejado homogeneamente; Corn plant nutrient variability in an homogeneously managed crop field

MONTEZANO, Zaqueu Fernando; CORAZZA, Edemar Joaquim; MURAOKA, Takashi
Fonte: Instituto Agronômico de Campinas Publicador: Instituto Agronômico de Campinas
Tipo: Artigo de Revista Científica
Português
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O conhecimento da variabilidade da nutrição de plantas e da produtividade em áreas cultivadas pode fornecer importantes subsídios na racionalização do uso de insumos e auxiliar no manejo da fertilidade do solo. O objetivo deste trabalho foi avaliar a variabilidade da nutrição mineral de plantas de milho por meio do fracionamento de um talhão cultivado comercialmente em células de manejo e verificar as relações com a produtividade. O estudo foi realizado na Fazenda Alto Alegre, em Planaltina (GO), em área de 373 hectares de Latossolo Vermelho-Amarelo Distroférrico, cultivado com milho na safra 2003/04. Traçado um polígono da área, procedeu-se sua divisão em 80 células de manejo de quatro hectares cada uma. A amostragem de folhas em cada célula seguiu uma diagonal com 12 pontos para compor uma amostra composta. Realizou-se a análise dos macro e micronutrientes nas folhas. A produtividade para cada célula foi obtida por meio de colhedora equipada com GPS. Na análise da variabilidade dos resultados foram considerados os parâmetros estatísticos descritivos. O teste ausência de correlação foi realizado com o nível de significância de 5%. A variabilidade da concentração dos nutrientes na folha indicadora do milho foi considerada baixa para N...

Produtividade e nutrição de mamona cultivada em área de reforma de canavial tratada com lodo de esgoto; Yield and plant nutrition of castor bean in crop rotation with sugarcane in a sewage sludge-treated soil

CHIARADIA, Jonas Jacob; CHIBA, Marcio Koiti; ANDRADE, Cristiano Alberto de; OLIVEIRA, Claudeir de; LAVORENTI, Arquimedes
Fonte: Sociedade Brasileira de Ciência do Solo Publicador: Sociedade Brasileira de Ciência do Solo
Tipo: Artigo de Revista Científica
Português
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A utilização de lodo de esgoto (LE) em solos agrícolas é uma das maneiras mais viáveis de destinação desse resíduo. O objetivo deste trabalho foi avaliar o efeito da aplicação de LE na nutrição e na produtividade da mamona cultivada em área de reforma de canavial, num Argissolo Vermelho-Amarelo distrófico textura argilosa. Os tratamentos testados constaram de quatro doses de lodo de esgoto: 0, 5, 10 e 20 t ha-1 (base seca), calculadas para fornecer N equivalente a 0, 37,5, 75 e 150 kg ha-1; um tratamento com fertilização mineral N-P2O5-K2O (75-40-80 kg ha-1respectivamente) e um controle sem qualquer fertilização. Os tratamentos com LE também receberam 40 kg ha-1 de P2O5 e 80 kg ha-1 de K2O. A mamoneira, cultivar IAC-Guarani, foi cultivada por cerca de 180 dias entre novembro de 2004 e maio de 2005. A aplicação de LE resultou em incremento estatisticamente significativo (p < 0,05) na produtividade e em outras características biométricas da mamona. A aplicação da dose equivalente a 10 t ha-1 de lodo resultou em um índice de eficiência agronômica de 85 %, em relação à adubação mineral. A disponibilidade de N foi o fator mais limitante no crescimento e na produtividade da mamona, e a taxa de mineralização do N utilizada subestimou o fornecimento de N pelo lodo em campo. Houve aumento significativo de Cu e Zn no solo com a aplicação das doses de lodo...

Reclaimed wastewater: Effects on citrus nutrition

PEREIRA, B. F. F.; HE, Z. L.; STOFFELLA, P. J.; MELFI, A. J.
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
Português
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The effects of irrigation with reclaimed wastewater (RWW) were compared with well water (WW) on citrus (Citrus paradisi Macfad. X Citrus aurantium L) nutrition. The deviation from the optimum percentage (DOP) index of macro- and micro-nutrients were used to evaluate the nutritional status: optimal (DOP = 0), deficiency (DOP < 0) or excess (DOP > 0). After 11 years of RWW irrigation the influence on nutrient concentration in plants decreased in the order: B > Zn > Mn = Ca > Cu > Mg > P > K. Reclaimed wastewater irritation positively affected citrus nutrition as it rendered the concentration of macronutrients, i.e. P, Ca, and K. closer to their optimum levels (Sigma DOP(macro) = 7). However micro-nutrients tended to be excessive in plants (EDOP(micro) = 753) due to imbalanced supply of these elements in the RWW, particularly, for B and Cu. Citrus groves with long-term RWW irrigation may exercised caution in monitoring concentrations of B and Cu to avoid plant toxicity and soil quality degradation. (C) 2011 Elsevier B.V. All rights reserved.; FAPESP (Sao Paulo Research Foundation)[06/56419-6]; University of Florida

Spider-fed bromeliads: seasonal and interspecific variation in plant performance

GONCALVES, Ana Zangirolame; MERCIER, Helenice; MAZZAFERA, Paulo; ROMERO, Gustavo Quevedo
Fonte: OXFORD UNIV PRESS Publicador: OXFORD UNIV PRESS
Tipo: Artigo de Revista Científica
Português
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Background and Aims Several animals that live on bromeliads can contribute to plant nutrition through nitrogen provisioning (digestive mutualism). The bromeliad-living spider Psecas chapoda (Salticidae) inhabits and breeds on Bromelia balansae in regions of South America, but in specific regions can also appear on Ananas comosus (pineapple) plantations and Aechmea distichantha. Methods Using isotopic and physiological methods in greenhouse experiments, the role of labelled ((15)N) spider faeces and Drosophila melanogaster flies in the nutrition and growth of each host plant was evaluated, as well as seasonal variation in the importance of this digestive mutualism. Key Results Spiders contributed 0.6 +/- 0.2% (mean +/- s.e.; dry season) to 2.7 +/- 1% (wet season) to the total nitrogen in B. balansae, 2.4 +/- 0.4% (dry) to 4.1 +/- 0.3% (wet) in An. comosus and 3.8 +/- 0.4% (dry) to 5 +/- 1% (wet) in Ae. distichantha. In contrast, flies did not contribute to the nutrition of these bromeliads. Chlorophylls and carotenoid concentrations did not differ among treatments. Plants that received faeces had higher soluble protein concentrations and leaf growth (RGR) only during the wet season. Conclusions These results indicate that the mutualism between spiders and bromeliads is seasonally restricted...

Nutrição mineral da cana‑de‑açúcar irrigada com efluente de esgoto tratado, em área com aplicação de fosfogesso; Mineral nutrition of sugarcane irrigated with sewage effluent in an area with phosphogypsum application

Blum, Julius; Melfi, Adolpho Jose; Montes, Celia Regina
Fonte: EMPRESA BRASIL PESQ AGROPEC; BRASILIA Publicador: EMPRESA BRASIL PESQ AGROPEC; BRASILIA
Tipo: Artigo de Revista Científica
Português
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O objetivo deste trabalho foi quantificar o aporte e a remoção de nutrientes em sistemas de cultivo  de cana‑de‑açúcar irrigados, ou não, com efluente de estação de tratamento de esgoto (EETE), com e sem  adição  de fosfogesso,  bem  como  avaliar  os  efeitos  desses sistemas  de  cultivo  no  estado  nutricional  das  plantas. Foram avaliados tratamentos sem irrigação e com irrigação a 100 e 150% da necessidade hídrica da  cultura. Os tratamentos com fosfogesso foram aplicados em área de terceiro corte, irrigada com EETE desde  o plantio. As  avaliações foram realizadas em duas safras. Os tratamentos não afetaram os rendimentos de  colmos. O tratamento com EETE e fosfogesso apresentou efeito sinérgico sobre o conteúdo de nitrogênio e de  enxofre nas plantas. O EETE beneficiou a nutrição das plantas quanto ao fósforo, mas não causou melhorias  na nutrição com potássio e enxofre. A nutrição com ferro, zinco e manganês não foi influenciada pelo aporte  desses micronutrientes pelo EETE. O  fósforo e o nitrogênio aportados na irrigação com EETE devem ser  considerados na recomendação de adubação. Porém...

Proporções de nitrato e amônio na nutrição e produção dos capins aruana e marandu.; Nitrate and ammonium proportions for aruana and marandu grasses nutrition and production.

Santos, Jorge Henrique da Silva
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 27/08/2003 Português
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Foi conduzido experimento em casa-de-vegetação do Departamento de Solos e Nutrição de Plantas da ESALQ – USP, durante o período de fevereiro a maio de 2002, com o objetivo de avaliar respostas produtivas, fisiológicas e nutricionais a proporções de nitrato e amônio, das forrageiras Panicum maximum cv. Aruana e Brachiaria brizantha cv. Marandu, cultivados em solução nutritiva, utilizando sílica como substrato. Foi empregado o delineamento experimental de blocos completos ao acaso, com quatro repetições e seis tratamentos. O nitrogênio foi estudado na dose de 210 mg L -1 e nas proporções respectivas de nitrato e amônio de 100/0; 85/15;70/30; 55/45; 40/60 e 25/75%. As soluções foram preparadas a partir da solução completa de Sarruge (1975), devidamente modificada para as proporções desses íons no suprimento de nitrogênio. Dois corte foram realizados nas plantas, separando-se os componentes da parte aérea em folhas emergentes, lâminas de folhas recém-expandidas, lâminas de folhas maduras e colmos mais bainhas. Após o segundo corte, as raízes foram separadas da sílica e lavadas. Durante o crescimento das plantas foram determinados a atividade da redutase do nitrato e o valor SPAD e na ocasião dos cortes foram contados os perfilhos e as folhas das plantas e foi medida a área foliar. No material seco foi obtido a produção de massa e nas amostras moídas foram determinadas as concentrações de nitrogênio total...

Interação de nitrogênio e potássio na nutrição, no teor de clorofila e na atividade da redutase do nitrato de plantas de trigo; Interaction of nitrogen and potassium in wheat nutrition, chlorophyll content, and nitrate activity reductase

Viana, Eloise Mello
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 22/06/2007 Português
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O conhecimento do comportamento vegetal quanto ao uso de nutrientes permite manusear ou modificar o sistema de cultivo para melhorar a eficiência na utilização de nitrogênio. O fornecimento de potássio para as plantas estimula o aproveitamento do nitrogênio, possibilitando que sua absorção, assimilação e, conseqüentemente, a produtividade sejam aumentadas. Com base nestes fatos, o objetivo deste estudo foi avaliar o efeito de combinações de doses de nitrogênio e de potássio na nutrição, no teor de clorofila e na atividade da enzima redutase do nitrato em plantas de trigo (Triticum aestivum L.). O experimento foi conduzido em casa de vegetação do Departamento de Ciência do Solo da ESALQ/USP, localizada no município de Piracicaba-SP, utilizando-se vasos de três litros onde foram acondicionadas amostras da camada 0-20 cm de um Argissolo Vermelho Amarelo Abrúptico. Utilizou-se esquema fatorial 52 fracionado, com combinações de cinco doses de nitrogênio (0; 70; 140; 210 e 280 mg dm -3) e de cinco doses de potássio (0; 50; 100; 150 e 200 mg dm-3), as quais foram distribuídas segundo delineamento experimental de blocos aleatorizados, com quatro repetições. As leituras SPAD das folhas do terço-médio das plantas de trigo foram realizadas 30 dias após a semeadura. Aos setenta e nove dias após a semeadura foi realizada determinação da atividade da enzima redutase do nitrato. Aos 80 dias após a semeadura...

Crescimento e marcha de absorção de nutrientes de crisântemo (Dendranthema grandiflora, Tzvelev.) cultivado em vaso; Growth and nutrients uptake curve of chrysanthemum (Dendranthema grandiflora, Tzvelev.) cultivated in pot

Rodrigues, Marcelo Antonio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 07/11/2013 Português
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O crisântemo cultivado em vaso é um dos produtos floríferos mais vendidos na floricultura brasileira, possuindo grande diversidade de cores, formas e tamanhos de inflorescências, além de possuir alta durabilidade após a colheita. Para tanto, é necessário o atendimento das exigências nutricionais da planta para possibilitar expressar seu potencial ornamental. Os objetivos deste trabalho foram analisar o crescimento da planta e caracterizar a marcha de absorção de nutrientes no cultivo em vaso do crisântemo, variedade cultivada ,,Fine Time". O experimento foi realizado na estufa climatizada do Setor de Floricultura do Colégio Politécnico da UFSM, Santa Maria - RS, no período de setembro a dezembro de 2012. O delineamento experimental foi inteiramente casualizado com oito tratamentos e seis repetições. As plantas foram coletadas e analisadas em intervalos que variaram de 7 a 14 dias dependendo da fase de desenvolvimento da planta. Os parâmetros de crescimento avaliados foram: comprimento das hastes, folhas e de raízes; número de folhas, raízes, brotações, botões florais e de inflorescências; largura e área das folhas; massa de matéria seca das folhas, raízes; botões florais; inflorescências, hastes e das plantas. Em relação aos nutrientes foi analisado teor...

The plant ionome revisited by the nutrient balance concept

Parent, Serge-Etienne; Parent, Leon Etienne; Jose Egozcue, Juan; Rozane, Danilo-Eduardo; Hernandes, Amanda; Lapointe, Line; Hebert-Gentile, Valerie; Naess, Kristine; Marchand, Sebastien; Lafond, Jean; Mattos, Dirceu; Barlow, Philip; Natale, William
Fonte: Frontiers Research Foundation Publicador: Frontiers Research Foundation
Tipo: Artigo de Revista Científica Formato: 10
Português
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Tissue analysis is commonly used in ecology and agronomy to portray plant nutrient signatures. Nutrient concentration data, or ionomes, belong to the compositional data class, i.e., multivariate data that are proportions of some whole, hence carrying important numerical properties. Statistics computed across raw or ordinary log-transformed nutrient data are intrinsically biased, hence possibly leading to wrong inferences. Our objective was to present a sound and robust approach based on a novel nutrient balance concept to classify plant ionomes. We analyzed leaf N, R K, Ca, and Mg of two wild and six domesticated fruit species from Canada, Brazil, and New Zealand sampled during reproductive stages. Nutrient concentrations were (1) analyzed without transformation, (2) ordinary log-transformed as commonly but incorrectly applied in practice, (3) additive log-ratio (air) transformed as surrogate to stoichiometric rules, and (4) converted to isometric log-ratios OH arranged as sound nutrient balance variables. Raw concentration and ordinary log transformation both led to biased multivariate analysis due to redundancy between interacting nutrients. The air- and ilr-transformed data provided unbiased discriminant analyses of plant ionomes...

Functional markers and a ‘systemic strategy’: convergency between plant breeding, plant nutrition and molecular biology

Arnholdt-Schmitt, Birgit
Fonte: Elsevier SAS Publicador: Elsevier SAS
Tipo: Artigo de Revista Científica Formato: 5885 bytes; application/pdf
Português
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Research perspectives towards sustainable plant production through plant breeding on abiotic stress tolerance require interdisciplinary competence. The present paper wants to strengthen awareness of important activities or current insights in plant breeding, plant nutrition and molecular biology to facilitate approximation of the disciplines and to direct efforts in molecular biology early in development towards application. As a consequence of recent discussion on appropriate approaches in systems biology towards crop improvement, a global ‘systemic strategy’ is presented to identify functional marker candidates for abiotic stress tolerance more efficiently.

Fertilization and cover crop effects on soil nitrogen and plant nutrition in a young guarana plantation

Trujillo,Lucerina; Lehmann,Johannes; Cravo,Manoel da Silva; Atroch,André Luiz; Nascimento Filho,Firmino José do
Fonte: Instituto Nacional de Pesquisas da Amazônia Publicador: Instituto Nacional de Pesquisas da Amazônia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2003 Português
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Fruit tree production is gaining an increasing importance in the central Amazon and elsewhere in the humid tropics, but very little is known about the nutrient dynamics in the soil-plant system. The present study quantified the effects of fertilization and cover cropping with a legume (Pueraria phaseoloides (Roxb.) Benth.) on soil nitrogen (N) dynamics and plant nutrition in a young guarana plantation (Paullinia cupana Kunth. (H.B. and K.) var. sorbilis (Mart.) Ducke) on a highly weathered Xanthic Ferralsol. Large subsoil nitrate (NO3-) accumulation at 0.3-3 m below the guarana plantation indicated N leaching from the topsoil. The NO3- contents to a depth of 2 m were 2.4 times greater between the trees than underneath unfertilized trees (P<0.05). The legume cover crop between the trees increased soil N availability as shown by elevated aerobic N mineralization and lower N immobilization in microbial biomass. The guarana N nutrition and yield did not benefit from the N input by biological fixation of atmospheric N2 by the legume cover (P>0.05). Even without a legume intercrop, large amounts of NO3- were found in the subsoil between unfertilized trees. Subsoil NO3- between the trees could be utilized, however, by fertilized guarana. This can be explained by a more vigorous growth of fertilized trees which had a larger nutrient demand and exploited a larger soil volume. With a legume cover crop...

Diagnosis and recommendation integrated system (DRIS) of tomato in greenhouse

Scucuglia,Cesar L; Creste,José E
Fonte: Associação Brasileira de Horticultura Publicador: Associação Brasileira de Horticultura
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2014 Português
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Plant nutrition is one of the most important factors for successful cultivation of tomatoes, especially in the greenhouse, and Diagnosis and Recommendation Integrated System (DRIS) is an alternative for fertilizer recommendation. This study aimed to establish DRIS norms for tomato plants growing in greenhouse located at Norte Pioneiro do Paraná region (Paraná State, Brazil). Chemical analysis of nutrients on leaves (N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn) of hybrid tomatoes (Colibri, Pizzadoro, Debora Max and Granadero), and respective yields of 61 growing areas in greenhouses (24.4 ha) were used. Samples were collected during April to December 2010, in five cities. Five levels of tomato yield (6, 7, 8, 9, and 10 kg plant-1) were used for establishing a database with all binary relationships among all the nutrients studied in all samples. The average, standard deviation and variance for each concentration of nutrient were calculated and it was done for relationship among nutrients, also, in each sub-population. We used 55 relationships which showed the highest ratio in the variance between sub-populations. The nutritional content of each nutrient and the nutrient balance index (IBN) of each production level were calculated. The best correlation between IBN and tomato yield was obtained with 8 kg plant-1 of tomato and this value was defined as an index to be used for DRIS. The nutritional diagnosis carried out in crops with yields below 6 kg plant-1 showed relative deficiencies of K and B and relative excess of Mg.

Focus on Plant Nutrition

Forde, Brian G.; Harper, Jeff F.; Kochian, Leon
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /09/2004 Português
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Spatial distribution of Yellow Sigatoka Leaf Spot correlated with soil fertility and plant nutrition.

FREITAS, A. S.; POZZA, E. A.; ALVES, M. C.; COELHO, G.; ROCHA, H. S.; POZZA, A. A. A.
Fonte: Precision Agriculture, 16 July, 2015. Publicador: Precision Agriculture, 16 July, 2015.
Tipo: Artigo em periódico indexado (ALICE) Formato: 14p.
Português
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This study analyzed the spatial distribution of Yellow Sigatoka Leaf Spot relative to soil fertility and plant nutritional status using geostatistics. The experimental area comprised 1.2 ha, where 27 points were georeferenced and spaced on a regular grid 18 9 18 m. The severity of Yellow Sigatoka, soil fertility and plant nutritional status were evaluated at each point. The spherical model was adjusted for all variables using restricted maximum likelihood. Kriging maps showed the highest infection rate of Sigatoka occurred in high areas of the field which had the highest concentration of sand, while the lowest disease was found in lower areas with lower silt, organic matter, total exchangeable bases, effective cation exchange capacity, base saturation, Ca andMgin soil, and foliar sulfur (S). These results may help farmers manage Yellow Sigatoka disease more effectively, with balanced fertilization and reduced fungicide application. This practice minimizes the environmental impact and cost of production while contributing to production sustainability.; 2015

The role of molybdenum in agricultural plant production

Kaiser, B.; Fitzpatrick, K.; Brady, J.; Phillips, T.; Tyerman, S.
Fonte: Oxford Univ Press Publicador: Oxford Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2005 Português
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Background: The importance of molybdenum for plant growth is disproportionate with respect to the absolute amounts required by most plants. Apart from Cu, Mo is the least abundant essential micronutrient found in most plant tissues and is often set as the base from which all other nutrients are compared and measured. Molybdenum is utilized by selected enzymes to carry out redox reactions. Enzymes that require molybdenum for activity include nitrate reductase, xanthine dehydrogenase, aldehyde oxidase and sulfite oxidase. Scope: Loss of Mo-dependent enzyme activity (directly or indirectly through low internal molybdenum levels) impacts upon plant development, in particular, those processes involving nitrogen metabolism and the synthesis of the phytohormones abscisic acid and indole-3 butyric acid. Currently, there is little information on how plants access molybdate from the soil solution and redistribute it within the plant. In this review, the role of molybdenum in plants is discussed, focusing on its current constraints in some agricultural situations and where increased molybdenum nutrition may aid in agricultural plant development and yields. Conclusions: Molybdenum deficiencies are considered rare in most agricultural cropping areas; however...

The role of arbuscular mycorrhizas in improving plant zinc nutrition under low soil zinc concentrations: a review

Cavagnaro, T.
Fonte: Kluwer Academic Publ Publicador: Kluwer Academic Publ
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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Many of the world’s soils are zinc (Zn) deficient. Consequently, many crops experience reduced growth, yield and tissue Zn concentrations. Reduced concentrations of Zn in the edible portions of crops have important implications for human Zn nutrition; this is a cause of global concern. Most terrestrial plant species form arbuscular mycorrhizas (AM) with a relatively limited number of specialized soil fungi. Arbuscular mycorrhizal fungi (AMF) can take up nutrients, including Zn, and transfer them to the plant, thereby enhancing plant nutrition. Under high soil Zn concentrations the formation of AM can also ‘protect’ against the accumulation of Zn in plant tissues to high concentrations. Here, a short review focusing on the role of AM in enhancing plant Zn nutrition, principally under low soil Zn concentrations, is presented. Effects of Zn on the colonisation of roots by AMF, direct uptake of Zn by AMF, the role of AM in the Zn nutrition of field grown plants, and emerging aspects of Zn molecular physiology of AM, are explored. Emergent knowledge gaps are identified and discussed in the context of potential future research.; Timothy R. Cavagnaro

The role of mycorrhizas in plant nutrition: field and mutant based approaches

Cavagnaro, T.; Martin, A.
Fonte: WCSS; DVD & Online Publicador: WCSS; DVD & Online
Tipo: Conference paper
Publicado em //2010 Português
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The majority of plants, including most crops, form arbuscular mycorrhizas (AM). These associations play an important role in the growth and nutrition of plants. Here we present results from our ongoing research on the role of AM in sustainable production systems. Firstly, we present results of a survey of the formation of AM by field grown tomato plants from across the south-eastern Australian processing tomato industry. This survey revealed low levels of colonisation, which could be explained by various farm management and edaphic factors. Secondly, to explore the role of AM in these farming systems, we grew a mycorrhiza defective tomato mutant and its mycorrhizal wild type progenitor in in-tact cores containing tomato farm soils. This novel genotypic approach to controlling for AM colonization allows us to study the formation and functioning of AM in field soils without the need to fumigate soils to establish non-mycorrhizal controls. Using this approach we found an important role for AM in the nutrition of tomato plants. Given the role of AM in plant nutrition, and the low levels of colonization in the survey, our ongoing research aims to identify better ways to manage AM in the field.; http://www.iuss.org/19th%20WCSS/WCSS_Main_Page.html; Timothy R Cavagnaro and Ash W Martin

Boron nutrition and yield of alfalfa cultivar crioula in relation to boron supply

Santos,Anacleto Ranulfo dos; Mattos,Waldssimiler Teixeira de; Almeida,Ana Aparecida da Silva; Monteiro,Francisco Antonio; Corrêa,Beatriz Dias; Gupta,Umesh C.
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2004 Português
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Alfalfa cultivar Crioula (Medicago sativa cv. Crioula) is grown in South Brazil and only a few studies on the plants' boron requirement are available. A greenhouse experiment was carried out with alfalfa to measure boron acquisition, production and distribution in the plant; data on critical level and production potentials were recorded. Plants were grown in ground quartz added with 1 L of solution, with the following boron rates: 0, 0.0625, 0.125, 0.25, 0.50, 1.00, and 2.00 mg L-1. Plants were harvested at 46 days of growth. Forage dry mass was increased by boron supply and dry matter accumulation was considerably low in control. Boron concentration in the leaves was higher than in the stems or roots. Boron utilization from the external solution reached 90% at 0.0625 mg L-1 and sharply decreased with further increasing boron rates. Boron concentration and content in the leaves and in plant tops were at maximum when applied boron was between 1.5 and 1.6 mg L-1. Critical levels of boron in plant were 61 mg kg-1 in the leaves and 39 mg kg-1 in plant tops for this cultivar of alfalfa.

Measurement of metal-complexing ability of polyfunctional macromolecules: a discussion of the relationship between the metal-complexing properties of extracted soil organic matter and soil genesis and plant nutrition

Peirano V., Pedro; Schalscha B., Eduardo; Aguilera S., S. María; Zunino Venegas, Hugo
Fonte: The Williams & Wilkins Co. Publicador: The Williams & Wilkins Co.
Tipo: Artículo de revista
Português
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Artículo de publicación ISI; Characterization of the metal-complexing ability of polyfunctional macromolecules through the determination of stability constants of their metalic complexes is discussed along with the validity of ascribing a relationship between the metal-ion complexing properties of organic matter extracted from the soil and the role of naturally occurring organic matter in soil in the processes of plant nutrition and soil genesis. The type of complex obtained when mixing metal-ion and complexant solutions will be a function of the molar ratio metal-ion/complexant. If Schubert's original experimental conditions (e.g., complexant concentration >> metal-ion one) are used, the MCh- or MChδ-type complexes will always be formed regardless of the polyfunctional character of the organic macromolecule (Ch). It is suggested that the overall stability constant of the saturated complex MαCh would describe in a comprehensive way the metal-complexing properties of such complexants. No reliable information about the role of soil organic matter in plant nutrition or soil genesis processes can be obtained by studyng the metal-complexing properties of these materials-or the number of active anionic group on the extracted molecules-will depend on the extent of depolymerization suffered by the naturally occurring soil organic matter during extraction. The methodology used up to the present to study the involvement of soil organic matter in plant nutrition or soil genesis processes through its metal-complexing ability urgently needs reevaluation.

Effects of elevated [CO2] and nitrogen nutrition on cytokinins in the xylem sap and leaves of cotton

Yong, Jean; Wong, Suan Chin; Letham, D Stuart; Hocart, Charles; Farquhar, Graham
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Português
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We measured the level of xylem-derived cytokinins (CKs) entering a cotton leaf, and the CK levels in the same leaf, thus enabling xylem sap and foliar CKs to be compared concurrently. Although zeatin was the dominant CK in xylem sap, zeatin, dihydrozeatin, and N6-(2-isopentenyl) adenine were present in approximately equimolar levels in leaves. Elevated [CO2] (EC) has an effect on the levels of cytokinins in sap and leaf tissues. This effect was modulated by the two levels of root nitrogen nutrition (2 and 12 mM nitrate). Growth enhancement (70%) in EC over plants in ambient [CO2] (AC) was observed for both nitrogen nutrition treatments. Low-nitrogen leaves growing in EC exhibited photosynthetic acclimation, whereas there was no sign of photosynthetic acclimation in high-nitrogen grown leaves. Under these prevailing conditions, xylem sap and leaf tissues were obtained for CK analysis. Higher nitrogen nutrition increased the delivery per unit leaf area of CKs to the leaf at AC. EC caused a greater increase in CK delivery to the leaf at low nitrogen conditions (106%) than at high nitrogen conditions (17%). EC induced a significant increase in CK content in low-nitrogen leaves, whereas CK content in leaf tissues was similar for high-nitrogen leaves growing in AC and EC.