CO^sub 2^ enrichment inhibits shoot nitrate assimilation in C^sub 3^ but not C^sub 4^ plants and slows growth under nitrate in C^sub 3^ plants

• Published in: Ecology (Durham) Vol. 93; no. 2; p. 355
• Main Authors: Bloom, Arnold J, Asensio, Jose Salvador Rubio, Randall, Lesley, Rachmilevitch, Shimon, Cousins, Asaph B, Carlisle, Eli A
• Format: Journal Article
• Language: English
• Published: Brooklyn Ecological Society of America 01-02-2012
• Subjects: Amino acids; Carbon dioxide; Flowers & plants; Metabolism; Nitrogen; Nonnative species; Plant growth
• ISSN: 0012-9658; 1939-9170

The ... concentration in Earth's atmosphere may double during this century. Plant responses to such an increase depend strongly on their nitrogen status, but the reasons have been uncertain. Here, we assessed shoot nitrate assimilation into amino acids via the shift in shoot and ... fluxes when plants received nitrate instead of ammonium as a nitrogen source (...). Shoot nitrate assimilation became negligible with increasing ... in a taxonomically diverse group of eight ... plant species, was relatively insensitive to ... in three ... species, and showed an intermediate sensitivity in two ... intermediate species. We then examined the influence of ... level and ammonium vs. nitrate nutrition on growth, assessed in terms of changes in fresh mass, of several ... species and a Crassulacean acid metabolism (CAM) species. Elevated ... (720 ...mol .../mol of all gases present) stimulated growth or had no effect in the five ... species tested when they received ammonium as a nitrogen source but inhibited growth or had no effect if they received nitrate. Under nitrate, two ... species grew faster at sub-ambient (~310 ...mol/mol) than elevated ... A CAM species grew faster at ambient than elevated or sub-ambient ... under either ammonium or nitrate nutrition. This study establishes that ... enrichment inhibits shoot nitrate assimilation in a wide variety of ... plants and that this phenomenon can have a profound effect on their growth. This indicates that shoot nitrate assimilation provides an important contribution to the nitrate assimilation of an entire ... plant. Thus, rising ... and its effects on shoot nitrate assimilation may influence the distribution of ... plant species. (ProQuest: ... denotes formulae/symbols omitted.)