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Potassium and phosphate absorption by excised ordinary and proteoid roots of the Proteaceae

1986; Elsevier BV; Volume: 52; Issue: 4 Linguagem: Inglês

10.1016/s0254-6299(16)31520-4

1727-9321

P.W. Vorster, J.H. Jooste,

Phosphorus and nutrient management

Potassium and phosphate absorption by excised ordinary and proteoid roots of certain species of the Proteaceae was investigated, using 86Rb (as substitute for 42K) and 32P as tracers. The respiratory uncoupler, 2,4-dinitrophenol (DNP), inhibited the uptake of potassium and phosphate. The greater inhibition obtained with proteoid roots possibly suggests that they possess a greater capacity for metabolic absorption than the ordinary roots. Absorption of potassium and phosphate over a concentration range of 0,005 – 50 mmol dm− 3 KCI and KH2PO4 respectively, was investigated. Lineweaver-Burk kinetic analysis of the data on potassium absorption in the low concentration range (0,005 – 1,0 mmol dm− 3 KCI) revealed a more effective absorption mechanism in the case of proteoid roots. Kinetic analysis of the data on phosphate absorption in both the low (0,02 – 1,0 mmol dm− 3 KH2PO4) and high (1,0 – 50 mmol dm− 3 KH2PO4) concentration ranges points to a more effective absorption mechanism in proteoid roots. Phosphate absorption by proteoid roots showed a distinct peak between pH 4 and 5,5. Opname van kalium en fosfaat deur afgesnyde gewone en proteoïede wortels van sekere soorte van die Proteaceae is ondersoek. As merkers is 86Rb (as plaasvervanger vir 42K) en 32P gebruik. Die respiratoriese ontkoppelaar, 2,4-dinitrofenol (DNP) het die opname van kalium en fosfaat deur gewone en proteoïede wortels onderdruk. Die groter mate van onderdrukking by proteoïede wortels dui moontlik daarop dat hulle oor 'n groter vermoë tot metaboliese opname as die gewone wortels beskik. Die opname van kalium en fosfaat oor 'n konsentrasiegebied van 0,005 – 50 mmol dm− 3 KCI en KH2PO4 onderskeidelik, is ondersoek. Lineweaver-Burk kinetiese analise van die gegewens ten opsigte van kaliumopname in die lae konsentrasiegebied (0,005 – 1,0 mmol dm− 3 KCI), dui op 'n meer effektiewe meganisme van opname by proteoïede as gewone wortels. Kinetiese analise van die resultate verkry tydens fosfaatopname in sowel die lae (0,02 – 1,0 mmol dm− 3 KH2PO4) as die hoë (1,0 – 50 mmol dm− 3 KH2PO4) konsentrasiegebied, dui ongetwyfeld op 'n meer effektiewe meganisme van metaboliese opname by proteoïede wortels. Fosfaatopname deur proteoïede wortels het 'n duidelike piek tussen pH 4 en 5,5 getoon.