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Research article - Peer-reviewed, 2021

Organic nitrogen enhances nitrogen nutrition and early growth of Pinus sylvestris seedlings

Lim, Hyungwoo; Jamtgard, Sandra; Oren, Ram; Gruffman, Linda; Kunz, Sabine; Nasholm, Torgny; Inselsbacher, Erich

Abstract

Boreal trees are capable of taking up organic nitrogen (N) as effectively as inorganic N. Depending on the abundance of soil N forms, plants may adjust physiological and morphological traits to optimize N uptake. However, the link between these traits and N uptake in response to soil N sources is poorly understood. We examined Pinus sylvestris L. seedlings' biomass growth and allocation, transpiration and N uptake in response to additions of organic N (the amino acid arginine) or inorganic N (ammonium nitrate). We also monitored in situ soil N fluxes in the pots following an addition of N, using a microdialysis system. Supplying organic N resulted in a stable soil N flux, whereas the inorganic N resulted in a sharp increase of nitrate flux followed by a rapid decline, demonstrating a fluctuating N supply and a risk for loss of nitrate from the growth medium. Seedlings supplied with organic N achieved a greater biomass with a higher N content, thus reaching a higher N recovery compared with those supplied inorganic N. In spite of a higher N concentration in organic N seedlings, root-to-shoot ratio and transpiration per unit leaf area were similar to those of inorganic N seedlings. We conclude that enhanced seedlings' nutrition and growth under the organic N source may be attributed to a stable supply of N, owing to a strong retention rate in the soil medium.

Keywords

amino acids; arginine; microdialysis; nitrate; soil N availability; water-use efficiency

Published in

Tree Physiology
2021, volume: 42, number: 3, pages: 513-522
Publisher: OXFORD UNIV PRESS

Authors' information

Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Oren, Ram
University of Helsinki
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Kunz, Sabine
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology
Swedish University of Agricultural Sciences, Department of Forest Ecology and Management
Swedish University of Agricultural Sciences, Department of Forest Genetics and Plant Physiology

UKÄ Subject classification

Forest Science

Publication Identifiers

DOI: https://doi.org/10.1093/treephys/tpab127

URI (permanent link to this page)

https://res.slu.se/id/publ/116402