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Nutrição e adubação de Aster ericoides (White Master) influenciando produção, qualidade e longevidade.; Nutrition and fertilization of Aster ericoides (White Master) related to prodution, quality and longevity.

Camargo, Mônica Sartori de
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 31/08/2001 PT
Relevância na Pesquisa
46.35%
Os objetivos do trabalho foram: estudar a resposta da cultura cultivada em solução nutritiva a doses de N e K quanto à produção e absorção de nutrientes; avaliar a nutrição e a produção da cultura cultivada em solo sob estufa comercial em 3 ciclos; avaliar os efeitos das adubações nitrogenada e potássica suplementares à fertilização do produtor na produção e absorção de nutrientes pela planta. Foram realizados dois experimentos: solução nutritiva e em solo (estufa comercial). O experimento em solução nutritiva foi instalado em blocos casualizados e constituído de um fatorial 4 x 4, com doses de N (42, 112, 210 e 406 mg L -1 N) e doses de K (39, 78, 234 e 468 mg L -1 K). As soluções nutritivas foram fornecidas por microaspersão em recipientes ( 7L ) contendo sílica e uma muda por vaso. Foram avaliadas a produção de matéria seca (flores, folhas e hastes), altura, número de flores, número de ramificações laterais principais por haste e nutrientes absorvidos. O experimento em solo, sob estufa comercial, foi dividido em duas partes: avaliação do estado nutricional da cultura quando da utilização da adubação do produtor e estudo das adubações nitrogenadas e potássicas aplicadas suplementarmente à fertilização do produtor. O primeiro experimento avaliou três ciclos da cultura ( fev.- maio; maio-ago; ago-dez. 1999) com 600 mil plantas por hectare no primeiro ciclo e 400 mil nos posteriores. A fertirrigação totalizou 86...

Assimilação do nitrogênio em diferentes regiões foliares de uma bromélia epífita com tanque; Nitrogen assimilation in different leaf portions of a tank epiphytic bromeliad

Takahashi, Cassia Ayumi
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 29/08/2008 PT
Relevância na Pesquisa
46.37%
A folha é o principal órgão de absorção e assimilação de nutrientes dos membros epífitos com tanque da família Bromeliaceae. Pouco se conhece sobre a nutrição dessas bromélias, entretanto algumas evidências (TAKAHASHI, 2007) indicaram a possibilidade de haver uma absorção preferencial do nitrogênio na porção basal e a assimilação desse nutriente na porção apical foliar. Para se compreender melhor os mecanismos de assimilação do nitrogênio utilizados pelas bromélias epífitas com tanque, foi proposto neste trabalho dois principais objetivos: 1) verificar possíveis diferenças quanto à capacidade de assimilação do nitrogênio em diferentes porções foliares de uma bromélia epífita com tanque; 2) constatar possível preferência em assimilar fonte nitrogenada orgânica ou inorgânica, quando ambas estão disponíveis no interior do tanque. A estratégia utilizada para o primeiro objetivo foi cultivar bromélias da espécie Vriesea gigantea, cultivadas em casa de vegetação e registrar em suas folhas as variações temporais das atividades enzimáticas da urease, redutase do nitrato (NR), sintetase da glutamina (GS), desidrogenase do glutamato dependente de NADH (GDH-NADH) e arginase após o fornecimento...

Sensor ótico no auxílio à recomendação de nitrogênio para a cultura da cana-de-açucar; Optical sensor to support the nitrogen recommendation on the sugarcane crop

Amaral, Lucas Rios do
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 21/01/2011 PT
Relevância na Pesquisa
46.2%
Mundialmente surge uma grande demanda por fontes alternativas de energia, propiciando ao setor sucroalcooleiro brasileiro uma intensa expansão, exigindo cada vez mais tecnologias que maximizem a produção e aumentem o retorno econômico, sendo de suma importância o correto manejo do nitrogênio aplicado à cultura da cana-de-açúcar. Dessa forma, o uso de técnicas da agricultura de precisão, em especial o uso de sensores que possibilitam a aplicação de fertilizantes nitrogenados em taxa variável e em tempo real, vem recebendo grande atenção por pesquisadores de todo o mundo. Sendo assim, a presente pesquisa teve como objetivo principal verificar a potencialidade de um sensor ótico ativo terrestre (Crop Circle, Holland scientific) em auxiliar na recomendação de nitrogênio em taxa variável para a cultura de cana-de-açúcar, de acordo com a necessidade de cada área. Para tanto, instalaram-se duas áreas experimentais, contando, em cada área, com um experimento em parcelas em um experimento em forma de faixas. O experimento em parcelas teve a finalidade de avaliar a resposta da cultura a doses de nitrogênio, mensurada por diferentes métodos. O experimento em forma de faixas de cana-deaçúcar teve a função de possibilitar o teste de diferentes estratégias de recomendação de nitrogênio...

Obtenção de algoritmo agronômico para sensor foto ativo de refletância vegetal visando à aplicação da adubação nitrogenada na cultura da cana-de-açucar; Calibration of an agronomic algorithm for a photo active reflectance sensor aiming to indicate nitrogen fertilizer in the sugarcane crop

Portz, Gustavo
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 16/06/2011 PT
Relevância na Pesquisa
46.33%
A nutrição nitrogenada, apesar de intensamente estudada, continua sendo um desafio aos produtores, especialmente em função da variabilidade encontrada no desenvolvimento da cultura nas áreas de produção comercial, muitas vezes em curtas distâncias. Recentemente esta variabilidade vem sendo associada ao uso de sensores opticos que detectam a refletância do dossel da cultura como forma de estimar a nutrição nitrogenada das plantas, podendo estes serem associados à aplicação em taxa variável em tempo real do fertilizante nitrogenado. Em cana-de-açúcar esses estudos ainda são escassos, e sendo uma cultura voltada para a produção de biomassa para geração de energia, tais sensores podem contribuir para otimizar o saldo positivo em produção de energia e baixar as emissão de carbono no sistema. Este trabalho apresenta o processo e mostra os resultados obtidos utilizando um sensor de nitrogênio e biomassa (N-SensorTM ALS, Yara International ASA) com o objetivo de indicar exigência na aplicação de nitrogênio em plantações comerciais de cana-de-açúcar. Oito talhões em produção comercial da cultura, localizados na região de Ribeirão Preto, SP, variando de 16 a 21 ha cada, foram monitorados. As condições de solo variaram de arenosos a argilosos...

Assimilação do nitrogênio em folhas de Vriesea gigantea (Bromeliaceae) durante a transição ontogenética do hábito atmosférico para o epífito com tanque; Nitrogen assimilation in leaves of Vriesea gigantea (Bromeliaceae) during the ontogenetic transition from atmospheric to tank epiphyte habit

Takahashi, Cassia Ayumi
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 10/03/2014 PT
Relevância na Pesquisa
46.45%
A fase de desenvolvimento é um importante fator a ser considerado em pesquisas sobre nutrição de bromélias. O hábito de vida dessas plantas pode mudar de: atmosférica (com folhas sem formar um tanque) para o com tanque ao longo do seu desenvolvimento. Algumas pesquisas mostraram que o conteúdo de nitrogênio foliar ou capacidade fotossintética são significantemente influenciados pela fase de desenvolvimento, porém não há registros de que a nutrição e o metabolismo do nitrogênio diferem entre bromélias jovens ou adultas. O objetivo principal deste projeto foi verificar se existem diferenças na dinâmica do metabolismo do nitrogênio (absorção, transporte e assimilação), decorrente da utilização de fontes de distintas (amônio, nitrato ou ureia), entre bromélias nas fases atmosférica ou adultas com tanque desenvolvido. Para tanto, plantas de Vriesea gigantea foram regadas com uma solução nutritiva que conteve 5mM de N total, disponível nas formas: 15NH4+ ou 15NO3- ou 15N-ureia. Foram feitas coletas temporais das raízes e de duas diferentes porções da folha (ápice e base) das bromélias jovens e de três regiões foliares (ápice, mediana e base) das folhas das bromélias adultas com tanque. Todas as amostras vegetais foram utilizadas na avaliação das atividades da: urease...

Forage yield and nitrogen nutrition dynamics of warm-season native forage genotypes under two shading levels and in full sunlight

Barro, Raquel Santiago; Varella, Alexandre Costa; Lemaire, Gilles; Medeiros, Renato Borges de; Saibro, Joao Carlos de; Nabinger, Carlos; Bangel, Felipe Villamil; Carassai, Igor Justin
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
56.3%
The successful achievement of a highly productive understorey pasture in silvopastoral systems depends on the use of well-adapted forage genotypes, showing good agronomic performance and persistence under shading and grazing. In this study, the herbage dry matter yield (DMY) and nitrogen nutrition dynamics were determined in three native warmseason grasses (Paspalum regnellii, Paspalum dilatatum and Paspalum notatum) and a forage legume (Arachis pintoi) under two shading levels compared with full sun. The experiment was conducted in the Campanha region, Bagé, state of Rio Grande do Sul, Brazil, during two evaluation cycles (2008/2009 and 2009/2010). Three shade cloth levels (0%, 50% and 80% of light restriction) were applied to the forage genotypes in a split plot design, in which shading levels were the main plot and forage genotypes were the subplots, with three replications. P. regnellii showed the highest accumulated DMY (1500 and 1700 g m-2, respectively, for the first and second evaluation cycles) at all shading levels and showed no DMY decreased under the heavy shade (80%). Average DMY over the four genotypes under the 50% shade level was higher or equal compared with full sun. Influence of rainfall was observed on the DMY performance of all genotypes: the positive effect of moderate shading (50%) on P. dilatatum and P. notatum DMY was associated to a low soil water availability status. Increased shading level resulted in high nitrogen nutrition index values on grasses...

Effect of nitrogen supply on growth and photosynthesis of sunflower plants grown in the greenhouse

Cechin, I; Fumis, T. D.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 1379-1385
ENG
Relevância na Pesquisa
46.18%
The effects of nitrogen availability on growth and photosynthesis were followed in plants of sunflower (Helianthus annuus L., var. CATISSOL-01) grown in the greenhouse under natural photoperiod. The sunflower plants were grown in vermiculite under two contrasting nitrogen supply, with nitrogen supplied as ammonium nitrate. Higher nitrogen concentration resulted in higher shoot dry matter production per plant and the effect was apparent from 29 days after sowing (DAS). The difference in dry matter production was mainly attributed to the effect of nitrogen on leaf production and on individual leaf dry matter. The specific leaf weight (SLW) was not affected by the nitrogen supply. The photosynthetic CO2 assimilation (A) of the target leaves was remarkably improved by high nitrogen nutrition. However, irrespective of nitrogen supply, the decline in photosynthetic CO2 assimilation occurred before the end of leaf growth. Although nitrogen did not change significantly stomatal conductance (gs), high-N grown plants had lower intercellular CO2 concentration (C-i) when compared with low-N grown plants. Transpiration rate (E) was increased in high-N grown plants only at the beginning of leaf growth. However, this not resulted in lower intrinsic water use efficiency (WUE). (C) 2004 Elsevier B.V.. All rights reserved.

SILICON IN ROW AND NITROGEN IN TOPDRESSING FERTILIZATION ON RICE UNDER DRY LAND AND SPRINKLER IRRIGATION CONDITIONS

Camarin Alvarez Artigiani, Angela Cristina; Costa Crusciol, Carlos Alexandre; Nascente, Adriano Stephan; Arf, Orivaldo; Felix Alvarez, Rita de Cassia
Fonte: Univ Federal Uberlandia Publicador: Univ Federal Uberlandia
Tipo: Artigo de Revista Científica Formato: 240-251
POR
Relevância na Pesquisa
46.39%
The objective of this work was to evaluate the effects of silicon application adjusted with nitrogen fertilization via top-dressing on grain productivity, the silicon contents of the soil, in the plant tissue and nitrogen contents in dry and irrigated conditions. The experimental outlining was from designed blocks with subdivided parcels and four repetitions. The treatments consisted of culture system (dry and irrigated) and the under parcels by the combination of silicon (0 and 100 kg ha(-1)), in magnesium and calcium silicate form (with 23% of SiO2), and four doses of N (urea) via top-dressing (0, 30, 60 and 90 kg ha(-1)). Silicon application at sowing furrow was a viable technique because it provided significant increase in the content of this element in the root growth of rice. The application of silicon in the sowing furrow did not change the content of the element nor the nitrogen nutrition in rice plants. The nitrogen application reduced the silicon content and increased nitrogen nutrition in rice plants. Silicon application at sowing furrow provided no increase in rice grain yield. When there was no water limitation to nitrogen fertilization enhanced linearly on rice grain yield, whereas under water stress the effect of nitrogen fertilization was limited.

Forage yield and nitrogen nutrition dynamics of warm-season native forage genotypes under two shading levels and in full sunlight

Barro,Raquel Santiago; Varella,Alexandre Costa; Lemaire,Gilles; Medeiros,Renato Borges de; Saibro,João Carlos de; Nabinger,Carlos; Bangel,Felipe Villamil; Carassai,Igor Justin
Fonte: Sociedade Brasileira de Zootecnia Publicador: Sociedade Brasileira de Zootecnia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2012 EN
Relevância na Pesquisa
56.3%
The successful achievement of a highly productive understorey pasture in silvopastoral systems depends on the use of well-adapted forage genotypes, showing good agronomic performance and persistence under shading and grazing. In this study, the herbage dry matter yield (DMY) and nitrogen nutrition dynamics were determined in three native warm-season grasses (Paspalum regnellii, Paspalum dilatatum and Paspalum notatum) and a forage legume (Arachis pintoi) under two shading levels compared with full sun. The experiment was conducted in the Campanha region, Bagé, state of Rio Grande do Sul, Brazil, during two evaluation cycles (2008/2009 and 2009/2010). Three shade cloth levels (0%, 50% and 80% of light restriction) were applied to the forage genotypes in a split plot design, in which shading levels were the main plot and forage genotypes were the subplots, with three replications. P. regnellii showed the highest accumulated DMY (1500 and 1700 g m-2, respectively, for the first and second evaluation cycles) at all shading levels and showed no DMY decreased under the heavy shade (80%). Average DMY over the four genotypes under the 50% shade level was higher or equal compared with full sun. Influence of rainfall was observed on the DMY performance of all genotypes: the positive effect of moderate shading (50%) on P. dilatatum and P. notatum DMY was associated to a low soil water availability status. Increased shading level resulted in high nitrogen nutrition index values on grasses...

Inter-specific variability in protein use by two vegetable crop species

Adamczyk,Bartosz; Godlewski,Mirosław
Fonte: Brazilian Journal of Plant Physiology Publicador: Brazilian Journal of Plant Physiology
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2010 EN
Relevância na Pesquisa
46.33%
It is now well-known that plants can uptake not only inorganic nitrogen but also organic nitrogen compounds, mainly amino acids. However, soil proteins are the main pool of amino acids. According to our earlier papers, plants can get access to this source of nitrogen using root-secreted proteases, but the level of proteolytic activity of such root-secreted proteases is species-specific. Our aim was to compare the use of protein as nitrogen source by two vegetable crops having high (Allium porrum) or low (Lactuca sativa) level of activity of root-secreted proteases. Seedlings were cultivated on Murashige and Skoog medium (MS), MS medium without inorganic nitrogen, MS medium without inorganic nitrogen, but with casein in concentration of 0.01%, 0.1% or 1%. Fresh weight of shoot of A. porrum was the highest for seedlings growing on culture medium with casein, but shoots of L. sativa obtained the highest weight growing on the culture medium with inorganic nitrogen. Allium porrum seedlings obtained 15-fold higher proteolytic activity in the culture medium than L. sativa. Seedlings of A. porrum using such high activity of proteases secreted by roots could provide a substantial pool of amino acids for intensive growth. The current studies conducted on A. porrum and L. sativa suggest that the efficiency of protein use in nitrogen nutrition by plants is species-specific.

Effects of Elevated [CO2] and Nitrogen Nutrition on Cytokinins in the Xylem Sap and Leaves of Cotton1

Yong, Jean W.H.; Wong, S. Chin; Letham, D. Stuart; Hocart, Charles H.; Farquhar, Graham D.
Fonte: American Society of Plant Physiologists Publicador: American Society of Plant Physiologists
Tipo: Artigo de Revista Científica
Publicado em /10/2000 EN
Relevância na Pesquisa
46.46%
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.

Effects of Two Strains of Tobacco Mosaic Virus on Photosynthetic Characteristics and Nitrogen Partitioning in Leaves of Nicotiana tabacum cv Xanthi during Photoacclimation under Two Nitrogen Nutrition Regimes.

Balachandran, S.; Osmond, C. B.; Makino, A.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /03/1994 EN
Relevância na Pesquisa
46.37%
Photoacclimation was studied in tobacco leaves (Nicotiana tabacum cv Xanthi) infected with two strains of tobacco mosaic virus (TMV) and grown under different light and nitrogen nutrition regimes. Photosynthetic acclimation measured by the quantum yield and the maximum rate in saturating light of CO2-saturated photosynthesis was impaired to a greater extent in tobacco leaves infected with TMV strain PV230 than in those infected with TMV strain PV42. Infection with TMV strain PV230 severely impaired photosynthetic acclimation at high light/low nitrogen and during transfer from low to high light. Expanding leaves showing chlorotic-mosaic symptoms had greatly reduced capacity to acclimate to high light compared with controls and with developed leaves without visible symptoms. We conclude that the failure of expanding leaves to acclimate was largely due to the destruction of chloroplasts in yellow areas of the tissue, accompanied by severe reduction in ribulose-1,5-bisphosphate carboxylase/oxygenase levels, and corresponding reduction in photosynthesis on a leaf-area basis. When corrected for areas of healthy green tissue, photoacclimation of infected leaves was the same as that of controls. Visible symptom development was greatest in high light/low nitrogen treatments. In developed leaves without visible symptoms...

Control of Leaf Expansion by Nitrogen Nutrition in Sunflower Plants 1: ROLE OF HYDRAULIC CONDUCTIVITY AND TURGOR

Radin, John W.; Boyer, John S.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/1982 EN
Relevância na Pesquisa
46.18%
Nitrogen nutrition strongly affected the growth rate of young sunflower (Helianthus annuus L.) leaves. When plants were grown from seed on either of two levels of N availability, a 33% decrease in tissue N of expanding leaves was associated with a 75% overall inhibition of leaf growth. Almost all of the growth inhibition resulted from a depression of the daytime growth rate. Measurements of pressure-induced water flux through roots showed that N deficiency decreased root hydraulic conductivity by about half. Thus, N deficiency lowered the steady-state water potential of expanding leaves during the daytime when transpiration was occurring. As a result, N-deficient leaves were unable to maintain adequate turgor for growth in the daytime. N deficiency also decreased the hydraulic conductivity for water movement into expanding leaf cells in the absence of transpiration, but growth inhibition at night was much less than in the daytime. N nutrition had no detectable effects on plastic extensibility or the threshold turgor for growth.

Studies on Genetic Male-Sterile Soybeans 1: IV. Effect of Male Sterility and Source of Nitrogen Nutrition on Accumulation, Partitioning, and Transport of Nitrogen

Israel, Daniel W.; Burton, Joseph W.; Wilson, Richard F.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /08/1985 EN
Relevância na Pesquisa
46.25%
Soybean (Glycine max [L.] Merr.) germplasm, isogenic except for loci controlling male sterility (ms1) and nodulation (rj1), was used to investigate the effects of reproductive tissue development and source of nitrogen nutrition on accumulation, transport, and partitioning of nitrogen in a greenhouse experiment. Nodulated plants were supplied nitrogen-free nutrient solution, and nonnodulated plants were supplied nutrient solution containing 20 millimolar KNO3. Plants were sampled from flowering until maturity (77 to 147 days after transplanting).

Can differences of nitrogen nutrition level among Medicago truncatula genotypes be assessed non-destructively?: Probing with a recombinant inbred lines population

Moreau, Delphine; Schneider, Charles; Huguet, Thierry; Salon, Christophe; Munier-Jolain, Nathalie
Fonte: Landes Bioscience Publicador: Landes Bioscience
Tipo: Artigo de Revista Científica
Publicado em /01/2009 EN
Relevância na Pesquisa
46.41%
The international consensus on Medicago truncatula as a model system has lead to the development of powerful approaches for dissecting the genetic and molecular bases of legume nitrogen nutrition. However, such approaches now come up against a poor knowledge of the phenotypic traits that should be used for the large-scale screening of the genotypic variability associated with nitrogen nutrition. This issue was unravelled in a previous report, in which an ecophysiological approach allowed a better understanding of the relationships between plant nitrogen nutrition and plant growth traits, for the model symbiotic association between M. truncatula cv. Jemalong and Rhizobium meliloti strain 2011. From this analysis, phenotypic traits were identified as potentially relevant for the large-scale screening of the genotypic variability. Here, by the phenotyping of a recombinant inbred lines population, we show that the proposed methodology provides a valuable support for assisting the detection of genetic variants affected for nitrogen uptake. Especially, the relative expansion rate of plant leaf area is identified as a good proxy for ranking genotypes according to their ability to uptake nitrogen in given environmental conditions. As leaf area can be measured non-destructively...

The Effect of Nitrogen Nutrition on Cluster Root Formation and Proton Extrusion by Lupinus albus

SAS, LIDIA; RENGEL, ZED; TANG, CAIXIAN
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
Publicado em 01/04/2002 EN
Relevância na Pesquisa
46.23%
Nitrogen nutrition can influence cluster root formation in many wild species, but the effect of N form on cluster root formation and root exudation by white lupin is not known. In a solution culture study, we examined the effect of N nutrition (ammonium, nitrate, both or N2 fixation) on cluster root formation and H+ extrusion by white lupin plants under deficient and adequate P supply. The number of cluster roots increased greatly when plants were supplied with 1 μm P compared with 50 μm P, the increase being 7·8‐fold for plants treated with (NH4)2SO4, 3‐fold for plants treated with KNO3 and NH4NO3, and 2·4‐fold for N2‐fixing plants. Under P deficiency, NH4+‐N supply resulted in production of a greater number and biomass of cluster roots than other N sources. Dry weight of cluster roots was 30 % higher than that of non‐cluster roots in P‐deficient plants treated with (NH4)2SO4 and NH4NO3. In plants treated with sufficient P (50 μm), the weight of non‐cluster roots was approx. 90 % greater than that of cluster roots. Both total (μmol per plant h–1) and specific (μmol g–1 root d. wt h–1) H+ extrusions were greatest from roots of plants supplied with (NH4)2SO4, followed by those supplied with NH4NO3 and N2 fixation...

Improvement of crop yield in dry environments:benchmarks, levels of organisation and the role of nitrogen

Sadras, V.O.; Richards, R.A.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Artigo de Revista Científica
Publicado em //2014 EN
Relevância na Pesquisa
46.29%
Crop yield in dry environments can be improved with complementary approaches including selecting for yield in the target environments, selecting for yield potential, and using indirect, trait- or genomic-based methods. This paper (i) outlines the achievements of direct selection for yield in improving drought adaptation, (ii) discusses the limitations of indirect approaches in the context of levels of organization, and (iii) emphasizes trade-offs and synergies between nitrogen nutrition and drought adaptation. Selection for yield in the water- and nitrogen-scarce environments of Australia improved wheat yield per unit transpiration at a rate of 0.12 kg ha–1mm–1yr–1; for indirect methods to be justified, they must return superior rates of improvement, achieve the same rate at lower cost or provide other cost- effective benefits, such as expanding the genetic basis for selection. Slow improvement of crop adaptation to water stress using indirect methods is partially related to issues of scale. Traits are thus classified into three broad groups: those that generally scale up from low levels of organization to the crop level (e.g. herbicide resistance), those that do not (e.g. grain yield), and traits that might scale up provided they are considered in a integrated manner with scientifically sound scaling assumptions...

Efficient production of lignocellulolytic enzymes xylanase, β-xylosidase, ferulic acid esterase and β-glucosidase by the mutant strain Aspergillus awamori 2B.361 U2/1

Gottschalk,Leda Maria Fortes; Paredes,Raquel de Sousa; Teixeira,Ricardo Sposina Sobral; Silva,Ayla Sant'Ana da; Bon,Elba Pinto da Silva
Fonte: Sociedade Brasileira de Microbiologia Publicador: Sociedade Brasileira de Microbiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
Relevância na Pesquisa
46.27%
The production of xylanase, β-xylosidase, ferulic acid esterase and β-glucosidase by Aspergillus awamori 2B.361 U2/1, a hyper producer of glucoamylase and pectinase, was evaluated using selected conditions regarding nitrogen nutrition. Submerged cultivations were carried out at 30 ºC and 200 rpm in growth media containing 30 g wheat bran/L as main carbon source and either yeast extract, ammonium sulfate, sodium nitrate or urea, as nitrogen sources; in all cases it was used a fixed molar carbon to molar nitrogen concentration of 10.3. The use of poor nitrogen sources favored the accumulation of xylanase, β-xylosidase and ferulic acid esterase to a peak concentrations of 44,880; 640 and 118 U/L, respectively, for sodium nitrate and of 34,580, 685 and 170 U/L, respectively, for urea. However, the highest β-glucosidase accumulation of 10,470 U/L was observed when the rich organic nitrogen source yeast extract was used. The maxima accumulation of filter paper activity, xylanase, β-xylosidase, ferulic acid esterase and β-glucosidase by A. awamori 2B.361 U2/1 was compared to that produced by Trichoderma reesei Rut-C30. The level of β-glucosidase was over 17-fold higher for the Aspergillus strain, whereas the levels of xylanase and β-xylosidase were over 2-fold higher. This strain also produced ferulic acid esterase (170 U/L)...

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
Relevância na Pesquisa
56.47%
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.

Sulphur and nitrogen nutrition influence the response of chickpea seeds to an added, transgenic sink for organic sulphur

Chiaiese, P; Ohkama-Ohtsu, N; Molvig, Lisa; Godfree, R; Dove, Hugh; Hocart, Charles; Fujiwara, Toru; Higgins, T J V; Tabe, Linda M
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
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In order to increase the concentration of the nutritionally essential sulphur amino acids in seed protein, a transgene encoding a methionine- and cysteine-rich protein, sunflower seed albumin (SSA), was transferred to chickpeas (Cicer arietinum L). Transgenic seeds that accumulated SSA contained more methionine and less oxidized sulphur than the controls, suggesting that additional demand for sulphur amino acids from the expression of the transgene stimulated sulphur assimilation. In addition, the activity of trypsin inhibitors, a known family of endogenous, sulphur-rich chickpea seed proteins, was diminished in transgenic, SSA-containing seeds compared with the non-transgenic controls. Together, these results indicate that the reduced sulphur sequestered into SSA was supplied partly by additional sulphur assimilation in the developing transgenic seeds, and partly by some diversion of sulphur amino acids from endogenous seed proteins. Growth of chickpeas on nutrient with a high sulphur-to-nitrogen ratio increased the total seed sulphur content and the accumulation of sulphur amino acids in the seeds, and partly mitigated the effect of SSA accumulation on the trypsin inhibitor amount. The results suggest that free methionine and O-acetylserine (OAS) acted as signals that modulated chickpea seed protein composition in response to the variation in sulphur demand...