Record ID No. |
327 |
Author(s) |
Valentine A.J., Kleinert A. , 2006 |
Affiliation |
Cape Peninsula University of Technology, Department of Horticulture, Faculty of Applied Sciences, POB 652, ZA-8000 Cape Town, South Africa |
Title |
Respiratory costs of P uptake in arbuscular mycorrhizal roots supplied with NH4+ and NO3- nutrition |
Source. Vol.(no):Page |
Symbiosis, 41(3):119-125p. |
Categories |
Arbuscular Mycorrhiza |
Subjects |
Ecology |
Host |
n.a. |
Organism |
n.a. |
Country |
South Africa, Africa |
Abstracts |
P uptake by arbuscular mycorrhizal (AM) roots can impose a C drain on host resources. However, it is not known how P uptake is influenced by the effects of inorganic N supply on AM colonisation and host root respiration. The respiratory costs of P uptake was studied in AM roots, supplied with NO3- and NH4+ nutrition. P uptake was higher in AM roots at both sources of inorganic N supply. This was correlated with the enhanced AM root respiration in host plants. In spite of AM colonisation being lower with NH4+ Supply than in NO3--fed roots, the respiratory O-2 consumption and CO2 release rates were still higher in AM roots than in non-AM roots at both forms of N. The uptake rates of NO3- and NH4+ were unaffected by AM colonisation. This was correlated with the partitioning of C from the incorporated root-zone CO2, into amino acid, also being unaffected by AM colonisation. The lower incorporation of root-zone CO2 by AM roots at both NO3- and NH4+ sources, concurs with the higher respiratory gas exchange quotient (Rq). These results show that the sink activity of AM roots is related to improved P uptake, irrespective of the influence of NO3- or NH4+ nutrition on AM colonisation and respiratory N metabolism.
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