Absorption and translocation of nitrogen in rhizomes of Leymus chinensis

Leymus chinensis is a dominant species in the Inner Mongolia steppe, northern China. Plant growth in northern China grassland is often limited by low soil nitrogen availability. The objective of this study is to investigate whether rhizomes of Leymus chinensis are involved in the contribution of N uptake. The N concentration, ¹⁵N concentration and ¹⁵N proportion in roots, rhizomes and shoots after 48 h exposure of roots (L_root) and rhizomes (L_rhizo) separately and roots and rhizomes together (L_r+r) to 0.1 mM ¹⁵NHNO₃ solution were measured using root‐splitting equipment and stable isotope (¹⁵N) techniques, respectively. The N content and dry mass were not affected by the labeling treatment. In contrast, the ¹⁵N concentration in shoots, rhizomes and roots was significantly increased by the labeling in rhizomes, indicating that the inorganic nitrogen was absorbed via rhizomes from the solution and can be transported to other tissues, with preference to shoots rather than roots. Meanwhile, the absolute N absorption and translocation among compartments were also calculated. The N absorption via rhizomes was much smaller than via roots; however, the uptake efficiency per surface unit via rhizomes was greater than via roots. The capacity and high efficiency to absorb N nutrient via rhizomes enable plants to use transient nutrient supplies in the top soil surface. Copyright © 2011 John Wiley & Sons, Ltd.