Destacadas de soja (Glycine max (L.) merril absorção de cálcio e fósforo por raízes var. IAC-2)

Absorption of calcium and phosphorus by excised soybean roots, var. IAC-2

Resumos

This paper deals with experiments designed to study the influence of several external factors on the uptake both of Ca+² and H2PO4 - by excised soybean roots. The main conclusions are as follows: 1) Ca uptake does not follow the usual Michaelian kynetics, the evidence suggesting the operation of passive mechanism; 2) R uptake is metabolic, a single mechanism being in operation; 3) pH has a strong effect both on Ca and R absorption; 4) The use both of lower temperature (O0C) and of respiratory poisons (cyanide) inibited phosphate uptake but had no effect on calcium absorption. 5) The obsorption of Ca+2 was lowered in the presence of Mg+² but not in that of K+; nitrate ions had no detrimental or sinergistic offect on the absorption of phosphate.

Destacadas de soja (Glycine max (L.) merril absorção de cálcio e fósforo por raízes var. IAC-2)^*

Absorption of calcium and phosphorus by excised soybean roots, var. IAC-2

E. Malavolta^I; A.F. Souza^II; G.S. Tunin^II; J.P. Dantas^II; B.F. Aquino^II; L.L. Foloni^II; E.G.S. Moreira^II; F.A.M. Lima^II; I. Chaves^II; J.F. Kefalás^II; J.F. Ferreira^II; G. A. Cavalcanti^II; F.O.B. Mota^II; E.C. Valle^II

^IDepartamento de Química e CENA, ESALQ, USP, Piracicaba, SP

^IIEstudantes de pós graduação em Solos e Nutrição de Plantas, ESALQ

RESUMO

A absorção do cálcio e do fósforo por raízes destacadas da soja var. IAC-2 foi estudada com ajuda de traçadores. Foram verificados os efeitos da concentração iônica externa do tempo, do pH, da temperatura, da aeração e de venenos respiratórios. Os dados sugerem que a absorção do cálcio tenha se dado passivamente, sendo ativa a do fósforo. A absorção cresceu com o pH e a temperatura. Os valores das constantes de Michaelis encontrados concordam com os da literatura.

SUMMARY

This paper deals with experiments designed to study the influence of several external factors on the uptake both of Ca+² and H₂PO₄ - by excised soybean roots.

The main conclusions are as follows:

1) Ca uptake does not follow the usual Michaelian kynetics, the evidence suggesting the operation of passive mechanism;

2) P uptake is metabolic, a single mechanism being in operation;

3) pH has a strong effect both on Ca and R absorption;

4) The use both of lower temperature (O⁰C) and of respiratory poisons (cyanide) inibited phosphate uptake but had no effect on calcium absorption.

5) The obsorption of Ca⁺² was lowered in the presence of Mg+² but not in that of K+; nitrate ions had no detrimental or sinergistic offect on the absorption of phosphate.

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LITERATURA CITADA

Entregue para publicação em 16/12/1976.

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*

Com ajuda da FAPESP, CNEN, CAPES e BNDE.

Datas de Publicação

• Publicação nesta coleção
  29 Maio 2012
• Data do Fascículo
  1976

Histórico

• Recebido
  16 Dez 1976