
TY  - JOUR
A1  - Isopp, Hubert 
A1  - Frehner, Marco 
A1  - Almeida, José P. F. 
A1  - Blum, Herbert 
A1  - Daepp, Markus 
A1  - Hartwig, Ueli A. 
A1  - Lüscher, Andreas 
A1  - Suter, Daniel 
A1  - Nösberger, Josef 
T1  - Nitrogen plays a major role in leaves when source-sink relations change: C and N metabolism in <emph type="2">Lolium perenne</emph> growing under free air CO<emph type="8">2</emph> enrichment
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2000
VL  - 27
IS  - 9
SP  - 851
EP  - 858
KW  - 
UR  - https://doi.org/10.1071/PP99151 
N2  - This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 Swards of Lolium perenne L. were grown in the field in a long-term free air CO2 enrichment (FACE) facility. The CO2 treatment was combined with two levels of N fertilization and regular defoliation, which resulted in plants with a wide range of source&#8211;sink relations. C and N metabolism were investigated to assess the role of carbohydrate and nitrogenous compounds in leaves in indicating source&#8211;sink relations. Sucrose exhibited the largest changes in contents during the day&#8211;night cycle; therefore, it was identified as the main short-term storage compound for night-time export. Fructan accumulation indicated the degree of surplus C supply in the source compared to C use in sinks. Nitrate content depended mainly on N fertilization, and was reduced under elevated pCO2. Nitrate appeared to indicate a current surplus of available N relative to the need for growth. Amino acid content responded strongly to N fertilization but decreased only slightly under elevated pCO2. Protein content, however, decreased significantly under elevated pCO2. The patterns of diurnal changes of C or N compounds did not differ between CO2 treatments. Down-regulation of photosynthesis appeared to occur when plants were extremely N-limited as under elevated pCO2, low N and at a late regrowth stage. 
ER  -

