title: Impairment of C(4) photosynthesis by drought is exacerbated by limiting nitrogen and ameliorated by elevated [CO(2)] in maize.
abstract: Predictions of future ecosystem function and food supply from staple C(4) crops, such as maize, depend on elucidation of the mechanisms by which environmental change and growing conditions interact to determine future plant performance. To test the interactive effects of elevated [CO(2)], drought, and nitrogen (N) supply on net photosynthetic CO(2) uptake (A) in the world's most important C(4) crop, maize (Zea mays) was grown at ambient [CO(2)] (∼385 ppm) and elevated [CO(2)] (550 ppm) with either high N supply (168 kg N ha(-1) fertilizer) or limiting N (no fertilizer) at a site in the US Corn Belt. A mid-season drought was not sufficiently severe to reduce yields, but caused significant physiological stress, with reductions in stomatal conductance (up to 57%), A (up to 44%), and the in vivo capacity of phosphoenolpyruvate carboxylase (up to 58%). There was no stimulation of A by elevated [CO(2)] when water availability was high, irrespective of N availability. Elevated [CO(2)] delayed and relieved both stomatal and non-stomatal limitations to A during the drought. Limiting N supply exacerbated stomatal and non-stomatal limitation to A during drought. However, the effects of limiting N and elevated [CO(2)] were additive, so amelioration of stress by elevated [CO(2)] did not differ in magnitude between high N and limiting N supply. These findings provide new understanding of the limitations to C(4) photosynthesis that will occur under future field conditions of the primary region of maize production in the world.
authors.affiliation: Department of Plant Biology and Institute for Genomic Biology, University of Illinois at Urbana-Champaign, 1206 West Gregory Drive, Urbana, IL 61801, USA.
authors.forename: R J Cody
authors.initials: RJ
authors.lastname: Markelz
authors.forename: Reid S
authors.initials: RS
authors.lastname: Strellner
authors.forename: Andrew D B
authors.initials: AD
authors.lastname: Leakey
mesh_terms: D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism*; D002940:Circadian Rhythm; D057231:Climate Change; D055864:Droughts; D005544:Forecasting; D009584:Nitrogen / Q000378:metabolism*; D010730:Phosphoenolpyruvate Carboxylase / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000201:enzymology / Q000378:metabolism / Q000502:physiology; D054046:Plant Stomata / Q000378:metabolism / Q000502:physiology; D011891:Rain; D012987:Soil / Q000737:chemistry; D013312:Stress, Physiological; D014867:Water / Q000378:metabolism*; D003313:Zea mays / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*
chemical_list: D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D010730:Phosphoenolpyruvate Carboxylase; D009584:Nitrogen