Premium
UPTAKE AND ASSIMILATION OF NITRATE AND AMMONIUM BY AN EVERGREEN FYNBOS SHRUB SPECIES PROTEA REPENS L. (PROTEACEAE)
Author(s) -
STOCK W. D.,
LEWIS O. A. M.
Publication year - 1984
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1984.tb04130.x
Subject(s) - proteaceae , evergreen , shoot , botany , shrub , repens , trifolium repens , biology , ammonium , horticulture , chemistry , organic chemistry
S ummary The uptake and assimilation of 15 N supplied either as NO 3 − or NH 4 + has been studied over a 9‐d period in Protea repens , a member of the Fynbos (South African Mediterranean‐type vegetation) to establish the preferred N source for plant growth and development. Low uptake and assimilation rates were found for both NO 3 − and NH 4 + feeding (4.8 and 5.9/μg 15 N g −1 fresh mass d −1 , respectively) and total 15 N absorbed over 9 d was greater in the NH 4 + ‐fed plants than in NO 3 + ‐fed ones. The form of N supplied did not cause significant changes in the total N content of the plants over the feeding period and no alteration in total N distribution patterns was evident, the shoot to root nitrogen ratio being 7:3. Distribution of 15 N between the soluble N fraction and the bound fraction within root and shoot was similar for both NO 3 + and NH 4 + ‐fed plants. In both treatments approximately 70 % of the 15 N was found in the root, mainly in the bound fraction. Protea repens appears to have adapted to the conditions prevalent in the later stages of Fynbos succession, not by showing an absolute requirement for a particular inorganic N form, but by an ability to absorb and assimilate small quantities of both NO 3 − and NH 4 + , which satisfy the low N demand of this slow growing, evergreen species.