Universidade de Lisboa Repositório da Universidade de Lisboa

Repositório da Universidade de Lisboa >
Faculdade de Ciências (FC) >
FC - Artigos em Revistas Internacionais >

Please use this identifier to cite or link to this item: http://hdl.handle.net/10451/4268

Título: Influx, efflux and net uptake of nitrate in Quercus suber seedlings
Autor: Mata, Catarina
Vemde, Nicole van
Clarkson, David T.
Martins-Loução, Maria Amélia
Lambers, Hans
Palavras-chave: Carbon budget
Net uptake
Quercus suber
Issue Date: 2000
Citação: Plant and Soil 221: 25–32, 2000
Resumo: Nitrate influx, efflux and net nitrate uptake were measured for the slow-growing Quercus suber L. (cork-oak) to estimate the N-uptake efficiency of its seedlings when grown with free access to nitrate.We hypothesise that nitrate influx, an energetically costly process, is not very efficiently controlled so as to avoid losses through efflux, because Q. suber has relatively high respiratory costs for ion uptake. Q. suber seedlings were grown in a growth room in hydroponicswith 1 mM NO- 3 . Seedlings were labelled with 15NO- 3 in nutrient solution for 5 min to measure influx and for 2 h for net uptake. Efflux was calculated as the difference between influx and net uptake. Measurements were made in the morning, afternoon and night. The site of nitrate reduction was estimated from the ratio of NO- 3 to amino acids in the xylem sap; the observed ratio indicated that nitrate reduction occurred predominantly in the roots. Nitrate influx was always much higher than net acquisition and both tended to be lower at night. High efflux occurred both during the day and at night, although the proportion of 15NO- 3 taken up that was loss through efflux was proportionally higher during the night. Efflux was a significant fraction of influx.We concluded that the acquisition system is energetically inefficient under the conditions tested.
Descrição: ACESSO via B-on: http://dx.doi.org/doi:10.1023/A:1004785331462
Arbitragem científica: yes
URI: http://dx.doi.org/doi:10.1023/A:1004785331462
ISSN: 0032-079X
Appears in Collections:FC - Artigos em Revistas Internacionais

Files in This Item:

File Description SizeFormat
0032079X_2000_25_32.pdf104,75 kBAdobe PDFView/Open
Restrict Access. You can request a copy!

Please give feedback about this item
FacebookTwitterDeliciousLinkedInDiggGoogle BookmarksMySpaceOrkut
Formato BibTex mendeley Endnote Logotipo do DeGóis 

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.


  © Universidade de Lisboa / SIBUL
Alameda da Universidade | Cidade Universitária | 1649-004 Lisboa | Portugal
Tel. +351 217967624 | Fax +351 217933624 | repositorio@reitoria.ul.pt - Feedback - Statistics
Promotores do RCAAP   Financiadores do RCAAP

Fundação para a Ciência e a Tecnologia Universidade do Minho   Governo Português Ministério da Educação e Ciência PO Sociedade do Conhecimento (POSC) Portal oficial da União Europeia