ISSN:
1432-2285
Keywords:
Wet N inputs
;
Labelled N
;
N partitioning
;
N accumulation
;
Per cent incorporation
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Cloned Sitka spruce grafts were subjected to NH4NO3 mist (1 mm day-1 equivalent) acidified with H2SO4, for 4 days a week, from April until November. Three N treatments at pH 5.0 used 0.01 mol m-3 15NH4 15NH3, 1.6 mol m-3 15NH4 NO3 or 1.6 mol m-3 NH4 15NO3. At pH 2.5, the treatments were15NH4 15NO3,15NH4NO3 and NH4 15NO3 all at 1.6 mol m-3. At the end of the growing season,15N was found in every part of the trees, even when NH4NO3 was supplied at 0.01 mol m-3. It was shown that both $$NH_{4^ + } $$ and $$NO_{3^ - } $$ could enter needles to a similar degree and be transported to the roots. No differences between pH treatments or clones could be demonstrated. Entry of labelled N via the roots, in those trees with unprotected compost, was reflected in higher fine root15N content, but no change in shoot15N levels. Per cent incorporation expressed as labelled N as a percentage of total N, was generally at its highest in bark, and in older needles in all treatments, values ranging from 5 to 11%. When15N content was expressed as total content for each tree part on a per tree basis, 25–36% was found in current year needles, with a further 12% in current year bark. The most reproducible data was that for dry weight of tree parts as per cent of the whole tree, where proportions compared closely between treatments and the two clones used. The implications of the results for cuticular transport mechanisms, N storage and internal cycling are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02185678
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