ISSN:
0931-1890
Keywords:
Key words Nitrogen
;
Photosynthesis
;
Picea sitchensis
;
Thuja plicata
;
Tsuga heterophylla
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract The effects of differing, exponentially increasing rates of N addition (0.025, 0.05, 0.07 and 0.09 gN gN–1day–1) on photosynthesis, discrimination against 13C and partitioning of foliar N to chlorophyll and major photosynthetic proteins were compared in seedlings of the evergreen conifers Picea sitchensis, Thuja plicata and Tsuga heterophylla. T. heterophylla had the lowest range of foliar N concentrations (Nlm). Across species, photosynthetic rates (A) increased linearly with Nlm to a maximum at 21 mg g–1 and declined at higher Nlms. Species differences in A resulted from differences in Nlm, not from differences in photosynthetic N use efficiency. Self-shading may have caused A to decline at a high Nlm in P. sitchensis and T. plicata. Measurements of gas exchange and δ13C suggested that carboxylation capacity increased more than did stomatal conductance as Nlm increased. The responses were small and confined to Nlms associated with the lesser rates of N addition. Concentrations of total protein, ribulose 1,5-bisphosphate carboxylase (RUBISCO) and the light harvesting chlorophyll a/b protein complex (LHC) increased with Nlm, but the fraction of foliar N allocated to RUBISCO and LHC increased with Nlm only in P. sitchensis and only between the 0.025 and 0.05N regimes. The responsiveness of A and concentrations of RUBISCO to Nlm were less than reported for deciduous C3 species.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00009648
Permalink
