Microrganismos do solo produtores de fosfatases em diferentes sistemas agrícolas
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Data
2002-12-01
Autores
Nahas, Ely [UNESP]
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Editor
Instituto Agronômico de Campinas
Resumo
Considerando-se que uma forma de prover fosfato disponível para as plantas é através da atividade mineralizadora microbiana do fósforo orgânico, 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 populações 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 mineralização do fósforo orgânico. 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 não 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.
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.
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.
Descrição
Palavras-chave
bactérias, fungos, fosfatase ácida, fosfatase alcalina, fosfato de rocha, superfosfato, braquiária, guandu, calagem, bacteria, fungi, acid phosphatase, alkaline phosphatase, rock phosphate, superphosphate, Brachiaria ruziziensis, Cajanus cajan, liming
Como citar
Bragantia. Instituto Agronômico de Campinas, v. 61, n. 3, p. 267-275, 2002.