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Search Results: 1 - 10 of 588 matches for " Nahas Ely "
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Microrganismos do solo produtores de fosfatases em diferentes sistemas agrícolas
Nahas, Ely;
Bragantia , 2002, DOI: 10.1590/S0006-87052002000300008
Abstract: considering that one way for providing available phosphate to plants is by the microbial activity for the mineralization of organic phosphorus, the influence of plants (brachiaria ruziziensis, cajanus cajan and control), fertilizers (superphosphate, rock phosphate and control) and liming (with and without lime) was evaluated in the microorganisms populations of the acid and alkaline phosphatase producers. among bacteria, 70,6% showed alkaline phosphatase activity and 58,2% acid phosphatase activity and among fungi, 64,3% and 84,7%, respectively. these numbers show that a significant population of microorganisms shows ability for organic phosphorus mineralization. restrictive effect of the c. cajan was observed on the bacteria and fungi producers of the alkaline and acid phosphatases whose numbers always were lower to those obtained with the b. ruziziensis or with the plots without cultivation. larger number of alkaline phosphatase bacterial producers was obtained in the treatments with superphosphate and control than that with rock phosphate. on the opposite, for fungi, a larger number was found in the plots with no fertilizer compared to the ones with fertilizer. the population of fungi having acid phosphatase activity decreased in the limed plots whereas the bacterial population increased. finally, the alkaline phosphatase bacterial producers showed higher enzymatic activity than those of the fungi.
Microrganismos do solo produtores de fosfatases em diferentes sistemas agrícolas
Nahas Ely
Bragantia , 2002,
Abstract: Considerando-se que uma forma de prover fosfato disponível para as plantas é através da atividade mineralizadora microbiana do fósforo organico, avaliou-se a influência da planta (braquiária, guandu e sem planta), dos fertilizantes (superfosfato simples, fosfato de rocha e sem adubo) e da calagem (com e sem calcário) nas popula es de microrganismos produtores de fosfatases ácida e alcalina. Do total de bactérias, 70,6% apresentaram atividade de fosfatase alcalina e 58,2% de fosfatase ácida e dos fungos, 64,3% e 84,7% respectivamente. Esses dados mostram número significativo de microrganismos com habilidade de mineraliza o do fósforo organico. Observou-se efeito restritivo do guandu sobre as bactérias e fungos produtores de fosfatases alcalina e ácida, cujos números foram sempre inferiores aos obtidos com a cultura de braquiária ou com as parcelas sem cultivo. Maior número de bactérias produtoras de fosfatase alcalina foi obtido nos tratamentos com superfosfato e controle do que com fosfato de rocha. Ao contrário, para os fungos, encontrou-se maior número nas parcelas n o fertilizadas que as adubadas com fosfato. O número de fungos com atividade de fosfatase ácida diminuiu por efeito da calagem, enquanto o das bactérias aumentou. Finalmente, o número de bactérias produtoras de fosfatase alcalina superou o de fungos.
FóSFORO Y EL ENCALADO SOBRE LAS FOSFATASAS Y LA PRODUCCIóN DE Braquiaria ruziziensis Y Cajanus cajan
Barroti,Giovane; Nahas,Ely;
Agronomía Tropical , 2003,
Abstract: summary phosphates act in the mineralization of soil organic p, however enzyme activity can be affected by plants, p inorganic sources or soil liming. this study evaluates the effect of the phosphorus sources and liming on activities of acid and alkaline phosphatases and on production of braquiaria ruziziensis and cajanus cajan. statistical design used was a randomized block in a 3x3x2 (plants x fertilizers x liming) with two replications. contents of total, organic and available phosphate of the soil were also determined. the acid phosphatase activity of the soil was 3,3 times more than the alkaline phosphatase activity and increased in the soil cultivated with b. ruziziensis in relation to the c. cajan or to the non cultivated soil. the alkaline phosphatase activity also increased in the soil cultivated with b. ruziziensis in relation to other treatments, but not significantiy. the alkaline phosphatase activity was repressed by the superphosphate, but not the acid phosphatase activity. in non lirned plots, the activity of both enzymes was repressed in the not fertilized soil or in the fertilized with superphosphate in relation to the rock phosphate. superphosphate increased phosphate avaliability of the soil, production and p uptake of b. ruziziensis and c. cajan. contents of total phosphate were largest in all the treatments that reccived rock phosphate or superphosphate.
Popula??o microbiana total e solubilizadora de fosfato em solo submetido a diferentes sistemas de cultivo
BARROTI, GIOVANE;NAHAS, ELY;
Pesquisa Agropecuária Brasileira , 2000, DOI: 10.1590/S0100-204X2000001000016
Abstract: the objective of the present study was to evaluate the effect of different plant species, phosphorus sources, and liming on the total microbial and phosphate-solubilizing population. in order to achieve that, bacteria and fungi capable of solubilizing hydroxyapatite providing available p were isolated. an experiment was carried out in a randomized factorial block design 3x3x2. the factors evaluated were plant species (control, brachiaria ruziziensis and cajanus cajan), fertilizers (control, simple superphosphate and rock phosphate, both at the dose of 400 kg ha-1 of p205) and liming (with and without lime). while the bacterial population increased due to the effect of liming, the fungal population also increased independently of liming in the soil cultivated with b. ruziziensis and fertilized with superphosphate. an increase of the microbial biomass-p compared to the control was observed under the influence of b. ruziziensis (23.9%), superphosphate (30.9%) or liming (46.9%). the number of solubilizing bacteria was favored by liming and by the planting of c. cajan fertilized with rock phosphate or with unfertilized b. ruziziensis. the solubilizing fungi increased in the absence of plants or fertilization and in the presence of c. cajan fertilized with rock phosphate. finally, liming enhanced more the growth of solubilizing fungi than did the control in the treatments using rock phosphate, b. ruziziensis or c. cajan.
Popula o microbiana total e solubilizadora de fosfato em solo submetido a diferentes sistemas de cultivo
BARROTI GIOVANE,NAHAS ELY
Pesquisa Agropecuária Brasileira , 2000,
Abstract: O objetivo deste trabalho foi avaliar o efeito de diferentes espécies de plantas, fontes de fósforo e calagem sobre a popula o microbiana total e solubilizadora de fosfato. Foram isolados fungos e bactérias capazes de solubilizar hidroxiapatita, proporcionando P solúvel. O experimento utilizado foi em blocos ao acaso com fatorial 3x3x2. E os fatores avaliados foram espécies de plantas (controle, braquiária e guandu), fertilizantes (controle, superfosfato simples e fosfato de rocha, ambos na dose de 400 kg ha-1 de P(2)0(5) ) e calagem (com e sem calcário). A popula o bacteriana cresceu pelo efeito da calagem, e a de fungos aumentou, independentemente da calagem, nas parcelas cultivadas com braquiária e fertilizadas com superfosfato. Foi constatado incremento de biomassa-P microbiana sobre o controle por influência da braquiária (23,9%), do superfosfato (30,9%) e da calagem (46,9%). O número de bactérias solubilizadoras foi favorecido pela calagem ou pelo plantio de guandu adubado com fosfato natural ou com braquiária sem aduba o. Os fungos solubilizadores aumentaram na ausência de planta ou de aduba o e na presen a de guandu com fosfato natural. Finalmente, a calagem favoreceumais o crescimento dos fungos solubilizadores, em compara o com o controle, nos tratamentos fosfato natural, braquiária ou guandu.
Bacterial diversity in soil in response to different plans, phosphate fertilizers and liming
Silva, Paulo da;Nahas, Ely;
Brazilian Journal of Microbiology , 2002, DOI: 10.1590/S1517-83822002000400005
Abstract: the diversity of bacterial isolates from soil in response to different plants (control, brachiaria ruziziensis and cajanus cajan), fertilization (control, simple superphosphate and rock phosphate) and liming (with and without lime) was evaluated. phenotypic and physiological characteristics of the isolates were recorded and organized in a file to identify the bacteria. among the isolates, 95% were gram-positive and 5% gram-negative rods. soil cultivated with b. ruziziensis favored the nonsporing gram-positive and gram-negative rods compared to soils with c. cajan or uncultivated. number of spore-forming gram-positive rods were higher in plots with superphosphate than in unfertilized soil or soil fertilized with rock phosphate. in unfertilized plots, larger number of gram-positive cocci and gram-negative rods was obtained than in fertilized plots. unlimed plots favored spore-forming gram-positive rods, gram-positive cocci and gram-negative rods, while with liming a larger proportion of nonsporing gram-positive rods was found. from 7 to 86% of the total isolates utilized different carbohydrates. the recording data used in this experiment was effective in the isolates identification, and might be useful for diagnosis of soil bacteria. bacillus, cellulomonas, rhodococcus, enterobacter, flavobacterium, micrococcus and arthrobacter were the genera more commonly found. bacterial diversity was enhanced in limed, unfertilized and plant cultivated plots.
Microrganismos produtores de hidrolases envolvidos nas transforma??es dos compostos do carbono e do nitrogênio do solo
Sanomiya, Luciana Terumi;Nahas, Ely;
Ciência Rural , 2003, DOI: 10.1590/S0103-84782003000500007
Abstract: the effect of plant cultures, brachiaria ruziziensis, cajanus cajan, of the phosphate fertilizers and of the liming on amilolytic, cellulolytic, proteolytic and ureolytic bacteria and fungi were investigated. the proportion of bacteria with enzymatic activity in relation to the total varied from 25 to 87% and fungi from 2 to 36%. the groups of bacteria increased its population in plots added with superphosphate and lime in relation to the other treatments (except the ureolytic that increased in plots not fertilized) and the fungi enhanced in the unfertilized (except the ureolytics that increased with superphosphate) and limed plots. the highest counts of ureolytic bacteria and proteolytic fungi were found in the soil cultivated with b. ruziziensis. the cm-cellulolytic (cm, cellulose microcrystalline) and ureolytic fungi enhanced in the uncultivated plots and the amilolytic and cmc-cellulolytic (cmc, carboxymethylcellulose) in the plots cultivated with c. cajan. the other groups of bacteria were not influenced by the cultivation system. the population and the enzymatic ability of the fungi groups were smaller than the bacteria, suggesting a smaller participation in the nutrients cycling in the soil. the bacteria presented multiple enzymatic activities, showing larger versatility than the fungi.
Solubiliza??o do fosfato de ferro em meio de cultura
Barroso, Cinthya Babá;Nahas, Ely;
Pesquisa Agropecuária Brasileira , 2008, DOI: 10.1590/S0100-204X2008000400012
Abstract: the objective of this work was to evaluate the efficiency of solubilization of fepo4 by aspergillus niger, in culture medium with different carbon (c) and nitrogen (n) sources, and enhancing concentrations of phosphate. the amount of soluble phosphate, acidity and final ph were determined after the fungus growth in a stationary culture at 30oc. efficiency of solubilization increased according to fungus growth, reaching the maximum at the 11th day (68%) and later decreased. in relation to c and n sources, the largest efficiencies of solubilization were found with mannitol (21%) and glutamic acid (17%). increasing phosphate concentration (0 to 1,330 μg ml-1), maximal efficiency of solubilization (70%) was found with 330 μg ml-1 po43-, and decreased up to 47% with 1,330 μg ml-1 po43-. the amount of acids produced was the factor that more influenced fepo4 solubilization, based in the positive and significant correlation between phosphate and acidity production.
Seasonal fluctuations of bacterial population and microbial activity in soils cultivated with eucalyptus and pinus
Rigobelo, Everlon Cid;Nahas, Ely;
Scientia Agricola , 2004, DOI: 10.1590/S0103-90162004000100015
Abstract: the accumulation and decomposition of litter in soils under forests depend on climatic and biotic conditions. this work evaluated the effect of monthly rainfall and temperature on total bacteria, and on the dehydrogenase and respiration microbial activities. the effects of organic matter, total organic c and soil moisture were also evaluated. performed from april, 1999 to march, 2000 in an eucalyptus-cultivated and pinus-cultivated oxisol (typic haplustox), the study showed that climate and the soil variables affect the total number of bacteria and the microbial activities. the highest air temperatures and rainfall intensities were found during the summer and, consequently, all the studied variables were maximal during this period. minimal values varied from autumn to winter or, for some parameters, up to spring. a positive correlation proved the influence of the organic matter, organic c and soil moisture on the total bacteria and on the respiratory and dehydrogenase activities. litter content was also higher in the summer as compared to the winter, but it correlated only with the total bacteria (r = 0.52***). however, the correlation between the litter content and organic matter (r = 0.64***) and soil moisture (r = 0.49**) suggest that the soil organic matter may have influenced microbial activity. all variables found in the eucalyptus soil were higher than that of pinus soil, probably favored by the best soil fertility and higher ph value.
Seasonal fluctuations of bacterial population and microbial activity in soils cultivated with eucalyptus and pinus
Rigobelo Everlon Cid,Nahas Ely
Scientia Agricola , 2004,
Abstract: The accumulation and decomposition of litter in soils under forests depend on climatic and biotic conditions. This work evaluated the effect of monthly rainfall and temperature on total bacteria, and on the dehydrogenase and respiration microbial activities. The effects of organic matter, total organic C and soil moisture were also evaluated. Performed from April, 1999 to March, 2000 in an Eucalyptus-cultivated and Pinus-cultivated Oxisol (Typic Haplustox), the study showed that climate and the soil variables affect the total number of bacteria and the microbial activities. The highest air temperatures and rainfall intensities were found during the Summer and, consequently, all the studied variables were maximal during this period. Minimal values varied from Autumn to Winter or, for some parameters, up to Spring. A positive correlation proved the influence of the organic matter, organic C and soil moisture on the total bacteria and on the respiratory and dehydrogenase activities. Litter content was also higher in the Summer as compared to the Winter, but it correlated only with the total bacteria (r = 0.52***). However, the correlation between the litter content and organic matter (r = 0.64***) and soil moisture (r = 0.49**) suggest that the soil organic matter may have influenced microbial activity. All variables found in the Eucalyptus soil were higher than that of Pinus soil, probably favored by the best soil fertility and higher pH value.
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