ISSN:
0931-1890
Keywords:
Key words Nitrogen
;
Picea sitchensis
;
Relative growth rates
;
Thuja plicata
;
Tsuga heterophylla
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Seedlings of Picea sitchensis, Thuja plicata and Tsuga heterophylla were supplied N hydroponically at one of four exponentially increasing rates of addition (0.09, 0.07, 0.05, or 0.025 gN–1 day–1) for up to 3 months in a naturally illuminated glasshouse. Relative growth rates (RGR) were analyzed as a function of N uptake, the allocation of assimilated N to foliage (LNFR), foliar N concentrations (Nla) and met assimilation rates (NAR), which were combined to estimate N productivity (RGR per unit whole-plant N concentration). Nitrogen accumulation, biomass and N partitioning and RGR and its components varied with species in response to the different N regimes. T. heterophylla had the lowest maximum whole-plant N concentrations (wpN) and specific absorption rates for N and exhibited the least plasticity in root : shoot ratios as wpN increased from 11 – 21 mg g–1. In all species, RGR increased linearly with wpN, while LNFR increased curvilinearly. Foliar N (Nla) increased linearly with wpN and NAR increased linearly with Nla. The RGRs of T. heterophylla were highest at wpNs up to 18 mg g–1, a result of higher foliar N use efficiencies (NAR/Nla). However, RGR increased more with wpN in T. plicata and P. sitchensis. Although LNFR increased with wpN in all species, foliar N use efficiency declined, possibly due to an increased partitioning of foliar soluble N to non-photosynthetic compounds. Thus, in each species, N productivity did not increase above intermediate levels of wpN: 14 mg g–1 in T. heterophylla, 16 mg g–1 in P. sitchensis and 17 mg g–1 in T. plicata.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00009647
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