Institute of Plant Sciences, Group of Agronomy and Plant Breeding, Swiss Federal Institute of Technology (ETH), Zu ¨rich, Switzerland Nitrogen Use Efficiency of Spring Wheat Genotypes under Field and Lysimeter Conditions Ch. Noulas, P. Stamp, A. Soldati, and M. Liedgens AuthorsÕ addresses: Dr Ch. Noulas, National Agricultural Research Foundation, Institute for Soil Mapping and Classification 1, Theophrastou Str. 41335, Larissa, Greece; Prof. Dr P. Stamp, Institute of Plant Sciences, Swiss Federal Institute of Technology, Universita¨tstrasse 2, CH-8092 Zu¨rich, Switzerland; Dr A. Soldati and Dr M. Liedgens (corresponding author; e-mail: markus.liedgens@ipw.agrl.ethz.ch), Institute of Plant Sciences, Swiss Federal Institute of Technology, Eschikon 33, CH-8315 Lindau, Switzerland With 3 tables Received April 22, 2003; accepted August 30, 2003 Abstract Lysimeters and neighbouring fields were used from 1998 to 2000 to assess parameters of N use efficiency of three Swiss spring wheat (Triticum aestivum L.) genotypes. An old (Albis), a new (Toronit) and an experimental geno- type (L94491) were compared with no and ample (250 kg N ha )1 ) N fertilizer supply. N fertilization increased biomass, grain yield and grain N concentration of all genotypes in all years and in both testing systems (field, lysimeters) but only a few genotype · N interactions were observed. Generally, Toronit was superior in producing biomass and grain yield and L94491 in accumulating N in the grain resulting in identical N biomass yields. Albis showed the lowest and Toronit the highest fertilizer recovery, irrespective of the method of calculation ( 15 N or difference method). The medium yielding L94491 recovered similar amounts of fertilizer N as Toronit, mainly due to the high N concentration in the biomass. The ranking of the genotypes for the investigated traits was similar in both testing systems and results comparable with those reported in the literature, indicating that the lysimeter facility is suitable for investigations of agronomic traits on soil–plant relationships, where a constant recording of the soil properties is required. Key words: 15 N — lysimeter — N fertilizer recov- ery efficiency (%) — nitrogen use efficiency com- ponents — spring wheat Introduction Higher production costs, inefficient use of energy resources, possible environmental pollution by nitrates in water and gaseous emissions in the atmosphere are linked to the inefficient use of N. Nitrogen use efficiency (NUE) has been defined as the grain yield produced per unit of N supply from soil and fertilizer (Sowers et al. 1994) and can be subdivided into components that identify soil and plant processes that contribute to the overall use of N (Moll et al. 1982). Grain yield and grain quality must be considered when growing wheat. High levels of nitrogen fertilizer result in a higher protein content in wheat grains. Increased efficiency of N use is realized when the nitrogen concentration in the kernels remain stable and grain yield increases at any given level of N application (Stenram et al. 1990, Doyle and Holford 1993, Ortiz–Monasterio et al. 1997). Feil (1997) reviewed environmental and genetic variation in protein content and found that genetic increases in grain yield are often accompanied by decreases in grain protein concentration. Field experiments indicated that not more than 50–60 % of applied N fertilizer is usually recov- ered under average growing conditions and that efficient timing and placement of N could increase recovery of applied N by 70–80 % (Legg and Meisinger 1982). The estimated recovery of fertil- izer N is often higher when the difference rather than the 15 N method is used (Rao et al. 1992). N fertilizer may stimulate N mineralization and this added-N interaction or priming effect has been suggested to be the reason for such conflicting results (Jenkinson et al. 1985). Cultivars can differ in NUE as a result of differences in N uptake (Rodgers and Barneix 1988), N remobilization and/or N utilization (Van Sanford and MacKown 1986). J. Agronomy & Crop Science 190, 111—118 (2004) Ó 2004 Blackwell Verlag, Berlin ISSN 0931-2250 U.S. Copyright Clearance Centre Code Statement: 0931–2250/2004/9002–0111 $15.00/0 www.blackwell-synergy.com