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- Title
Phosphorus affects growth and partitioning of nitrogen to Rubisco in Pinus pinaster.
- Authors
Warren, Charles R.; Adams, Mark A.
- Abstract
We tested the hypothesis that photosynthetic and growth responses to phosphorus (P) are functions of differences in the partitioning of nitrogen (N) among different compounds, particularly ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). We tested this hypothesis in: (a) a greenhouse experiment with mycorrhizal seedlings of Pinus pinaster Ait. grown in sand culture for 4 months with six factorial combinations of N (0.125 and 2.0 mM) and P (0.02, 0.08 and 0.34 mM); and (b) a field study in which P was applied at five rates (up to 175 kg ha−1) to 2-year-old P. pinaster growing on P-deficient siliceous sand. After 4 months of nutrient addition or 2 years after fertilizer application, we measured light-saturated rates of photosynthesis, growth, and N and P allocation in needles. Growth of P. pinaster increased significantly with increasing concentrations of P, as did the concentration of P in needles. Concentrations of P and Rubisco were positively related, whereas those of N and Rubisco were unrelated. At low-P supply, the Rubisco/Chl ratio varied between 8.5 and 12 mmol mol−1. With P supply in excess of requirement (needle N:P ratio = 2–12) the Rubisco/Chl ratio increased to between 24 and 26 mmol mol−1. Rates of light-saturated photosynthesis were unaffected by P supply because adequate concentrations of P were maintained in plants in all treatments. Orthophosphate accumulated in needles of plants receiving a high P supply, which may allow growth to continue for periods under P deficiency, provided that other nutrients also accumulate. In the case of N, Rubisco may fill this role.
- Subjects
PHOSPHORUS; CLUSTER pine; PLANT growth; NITROGEN; FERTILIZERS
- Publication
Tree Physiology, 2002, Vol 22, Issue 1, p11
- ISSN
0829-318X
- Publication type
Article
- DOI
10.1093/treephys/22.1.11