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Effects of nitrogen supply on the seasonal re‐mobilization of nitrogen in Ulex europaeus
Author(s) -
THORNTON B.,
MILLARD P.,
TYLER M. R.
Publication year - 1995
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.1469-8137.1995.tb04332.x
Subject(s) - shoot , nitrogen , ulex europaeus , nitrogen fixation , nutrient , growing season , biology , botany , horticulture , agronomy , chemistry , ecology , biochemistry , organic chemistry , agglutinin , lectin
SUMMARY Nodulated plants of Ulex europaeus L. (gorse) were grown over two seasons in sand. Nutrients were supplied as solutions containing either 0‐25 mol m ‐3 NO 3 ‐> , 5·0 mol m ‐3 NO 3 , 0·25 mol m ‐3 NH 4 ‐+ or 5·0 mol m ‐3 NH 4 + , as Ca(NO 3 ) 2 or (NH 4 ) 2 SO 4 . In the first season all nitrogen (N) was enriched with 15 N to 5 atom %. In the second season half the plants received the same solution, while the remaining plants received a similar solution in terms of form and amount of nitrogen but at natural abundance. Throughout the second season eight destructive harvests were performed. Plants were separated into roots, nodules, previous season's shoot, new shoot and flowers, and then analysed for total N and 15 N content. This allowed estimates to be made of total root N uptake, N 2 fixation and the contribution of re‐mobilization to the nitrogen content of new shoot growth in the second season. The main source of N was N 2 fixation for plants receiving a low supply of N and root uptake for plants receiving a high supply of N. Plants supplied high NH 4+ stored more N over winter than did plants given other treatments. The proportion of over‐wintering stores that were re‐mobilized to support spring shoot growth was unaffected by the capacity of the plants for N 2 fixation.