Nitrogen nutrition of Myriophyllum spicatum: uptake and translocation of ¹⁵N by shoots and roots

Summary Intact Myriophyllum spicatum plants were grown in compartmentalized containers in a growth room so that the roots were separated from the shoots by a watertight partition. Nitrogen 15 N was added to the water or sediment to trace the uptake of inorganic N by the plant shoots or roots. Myriophyllum spicatum is capable of taking up inorganic N through both roots and shoots. Plant N requirements can apparently be met by root uptake alone. However, when about 0·1 mg/l of NH 4 ‐N were present in the water, foliar uptake supplied more N to the plants than did root uptake. Foliar uptake of NH 4 ‐N was found to be several times faster than that of NO 3 ‐N when both forms of N were present in the water. Only about 1% of the N taken up by the roots was subsequently released to the water through the foliage.