Regulation of nitrogen uptake by Fagus sylvatica on a whole plant level - interactions between cytokinins and soluble N compounds. - Collier,M..D..; Fotelli,M..N..; Nahm,M..; Kopriva,S..; Rennenberg,H..; Hanke,D..E..; Gessler,A.. (Plant, Cell and Environment, 2003)