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Drought limitation of photosynthesis differs between C 3 and C 4 grass species in a comparative experiment
Author(s) -
TAYLOR S. H.,
RIPLEY B. S.,
WOODWARD F. I.,
OSBORNE C. P.
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.1365-3040.2010.02226.x
Subject(s) - photosynthesis , biology , stomatal conductance , botany , drought tolerance , nitrogen , c4 photosynthesis , agronomy , chemistry , organic chemistry
Phylogenetic analyses show that C 4 grasses typically occupy drier habitats than their C 3 relatives, but recent experiments comparing the physiology of closely related C 3 and C 4 species have shown that advantages of C 4 photosynthesis can be lost under drought. We tested the generality of these paradoxical findings in grass species representing the known evolutionary diversity of C 4 NADP‐me and C 3 photosynthetic types. Our experiment investigated the effects of drought on leaf photosynthesis, water potential, nitrogen, chlorophyll content and mortality. C 4 grasses in control treatments were characterized by higher CO 2 assimilation rates and water potential, but lower stomatal conductance and nitrogen content. Under drought, stomatal conductance declined more dramatically in C 3 than C 4 species, and photosynthetic water‐use and nitrogen‐use efficiency advantages held by C 4 species under control conditions were each diminished by 40%. Leaf mortality was slightly higher in C 4 than C 3 grasses, but leaf condition under drought otherwise showed no dependence on photosynthetic‐type. This phylogenetically controlled experiment suggested that a drought‐induced reduction in the photosynthetic performance advantages of C 4 NADP‐me relative to C 3 grasses is a general phenomenon.