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The growth response of C 4 plants to rising atmospheric CO 2 partial pressure: a reassessment
Author(s) -
Ghannoum O.,
Caemmerer S. Von,
Ziska L. H.,
Conroy J. P.
Publication year - 2000
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 - 10.1046/j.1365-3040.2000.00609.x
Subject(s) - transpiration , photosynthesis , stomatal conductance , shoot , water use efficiency , horticulture , carbon assimilation , botany , agronomy , chemistry , biology
Despite mounting evidence showing that C 4 plants can accumulate more biomass at elevated CO 2 partial pressure (p(CO 2 )), the underlying mechanisms of this response are still largely unclear. In this paper, we review the current state of knowledge regarding the response of C 4 plants to elevated p(CO 2 ) and discuss the likely mechanisms. We identify two main routes through which elevated p(CO 2 ) can stimulate the growth of both well‐watered and water‐stressed C 4 plants. First, through enhanced leaf CO 2 assimilation rates due to increased intercellular p(CO 2 ). Second, through reduced stomatal conductance and subsequently leaf transpiration rates. Reduced transpiration rates can stimulate leaf CO 2 assimilation and growth rates by conserving soil water, improving shoot water relations and increasing leaf temperature. We argue that bundle sheath leakiness, direct CO 2 fixation in the bundle sheath or the presence of C 3 ‐like photosynthesis in young C 4 leaves are unlikely explanations for the high CO 2 ‐responsiveness of C 4 photosynthesis. The interactions between elevated p(CO 2 ), leaf temperature and shoot water relations on the growth and photosynthesis of C 4 plants are identified as key areas needing urgent research.