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Forskningsartikel2021Vetenskapligt granskadÖppen tillgång

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


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.


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

Publicerad i

Tree Physiology
2021, Volym: 42, nummer: 3, sidor: 513-522