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The rate‐limiting step for CO 2 assimilation at different temperatures is influenced by the leaf nitrogen content in several C 3 crop species
Author(s) -
YAMORI WATARU,
NAGAI TAKESHI,
MAKINO AMANE
Publication year - 2011
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2011.02280.x
Subject(s) - limiting , nitrogen , assimilation (phonology) , agronomy , crop , environmental science , chemistry , horticulture , biology , engineering , mechanical engineering , organic chemistry , linguistics , philosophy
Effects of nitrogen (N) supply on the limiting step of CO 2 assimilation rate ( A ) at 380 µ mol mol −1 CO 2 concentration ( A 380 ) at several leaf temperatures were studied in several crops, since N nutrition alters N allocation between photosynthetic components. Contents of leaf N, ribulose 1·5‐bisphosphate carboxylase/oxygenase (Rubisco) and cytochrome f (cyt f ) increased with increasing N supply, but the cyt f /Rubisco ratio decreased. Large leaf N content was linked to a high stomatal ( g s ) and mesophyll conductance ( g m ), but resulted in a lower intercellular ( C i ) and chloroplast CO 2 concentration ( C c ) because the increase in g s and g m was insufficient to compensate for change in A 380 . The A ‐ C c response was used to estimate the maximum rate of RuBP carboxylation ( V cmax ) and chloroplast electron transport ( J max ). The J max / V cmax ratio decreased with reductions in leaf N content, which was consistent with the results of the cyt f /Rubisco ratio. Analysis using the C 3 photosynthesis model indicated that A 380 tended to be limited by RuBP carboxylation in plants grown at low N concentration, whereas it was limited by RuBP regeneration in plants grown at high N concentration. We conclude that the limiting step of A 380 depends on leaf N content and is mainly determined by N partitioning between Rubisco and electron transport components.