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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Loss of photosynthetic efficiency in the shade. An Achilles heel for the dense modern stands of our most productive C4 crops?
AU - Pignon, C.P.
AU - Jaiswal, D.
AU - McGrath, J.M.
AU - Long, S.P.
PY - 2017/1/1
Y1 - 2017/1/1
N2 - The wild progenitors of major C4 crops grew as individuals subjected to little shading. Today they are grown in dense stands where most leaves are shaded. Do they maintain photosynthetic efficiency in these low light conditions produced by modern cultivation? The apparent maximum quantum yield of CO2 assimilation (φ CO2max, app ), a key determinant of light-limited photosynthesis, has not been systematically studied in field stands of C4 crops. φCO2max, app was derived from the initial slope of the response of leaf CO2 uptake (A) to photon flux (Q). Leaf fractional light absorptance (α) was measured to determine the absolute maximum quantum yield of CO2 assimilation on an absorbed light basis (φCO2max, abs ). Light response curves were determined on sun and shade leaves of 49 field plants of Miscanthus × giganteus and Zea mays following canopy closure. φCO2max, app and φCO2max, abs declined significantly by 15-27% (P<0.05) with canopy depth. Experimentally, leaf age was shown unlikely to cause this loss. Modeling canopy CO2 assimilation over diurnal courses suggested that the observed decline in φCO2max, app with canopy depth costs 10% of potential carbon gain. Overcoming this limitation could substantially increase the productivity of major C4 crops. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.
AB - The wild progenitors of major C4 crops grew as individuals subjected to little shading. Today they are grown in dense stands where most leaves are shaded. Do they maintain photosynthetic efficiency in these low light conditions produced by modern cultivation? The apparent maximum quantum yield of CO2 assimilation (φ CO2max, app ), a key determinant of light-limited photosynthesis, has not been systematically studied in field stands of C4 crops. φCO2max, app was derived from the initial slope of the response of leaf CO2 uptake (A) to photon flux (Q). Leaf fractional light absorptance (α) was measured to determine the absolute maximum quantum yield of CO2 assimilation on an absorbed light basis (φCO2max, abs ). Light response curves were determined on sun and shade leaves of 49 field plants of Miscanthus × giganteus and Zea mays following canopy closure. φCO2max, app and φCO2max, abs declined significantly by 15-27% (P<0.05) with canopy depth. Experimentally, leaf age was shown unlikely to cause this loss. Modeling canopy CO2 assimilation over diurnal courses suggested that the observed decline in φCO2max, app with canopy depth costs 10% of potential carbon gain. Overcoming this limitation could substantially increase the productivity of major C4 crops. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.
KW - C4 photosynthesis
KW - Canopy photosynthesis
KW - Corn
KW - Crop photosynthesis
KW - Crop yield
KW - Food security
KW - Maize
KW - Miscanthus
KW - Planting density
KW - Quantum yield
KW - Shade acclimation
KW - biological model
KW - darkness
KW - maize
KW - metabolism
KW - photosynthesis
KW - Darkness
KW - Models, Biological
KW - Photosynthesis
KW - Zea mays
U2 - 10.1093/jxb/erw456
DO - 10.1093/jxb/erw456
M3 - Journal article
VL - 68
SP - 335
EP - 345
JO - Journal of Experimental Botany
JF - Journal of Experimental Botany
SN - 0022-0957
IS - 2
ER -