title: [Root activity and nitrogen assimilation of rice (Oryza sativa) under free-air CO2 enrichment].
abstract: With Free-Air CO2 Enrichment(FACE) technique, this paper studied the root activity and amino acid(aa) synthesis of rice (Oryza sativa )at low N(LN, 150 kgN x hm(-2)) and normal N(NN, 250 kgN x hm(-2)) under ambient air and elevated atmospheric CO2 (Ambient + 200 micromol x mol(-1)). Under elevated CO2, the xylem exudates per hill changed little, while the xylem exudates per stem declined by 1.4% - 21.7% as the result of greater tiller numbers. At tillering and heading stages, elevated CO2 increased aa N/inorganic N in xylem exudates by 11.1% - 143.1%, but did not affect the aa concentration in xylem exudates and the total amount of aa in roots significantly. However, at 35 days after heading, the aa N/inorganic N ratio decreased by 38.1% (LN) and 29.2% (NN) under elevated CO2. FACE also declined the aa concentration in xylem exudates by 34.0% (LN) and 44.7% (NN), and the total amount of aa by 50.8% (LN) and 40.0% (NN), which meant the retarded capability of aa synthesis in roots. N amendment led to a decrease of aa N/inorganic N in xylem exudates by 19.5% (Ambient) and 36.8% (FACE) at heading stage, as the result of unaffected aa and increased inorganic N concentration. There existed a significantly antagonistical CO2 x N interaction on aa N/inorganic N at heading stage.
authors.affiliation: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China. pangjing2286@sina.com
authors.forename: Jing
authors.initials: J
authors.lastname: Pang
authors.forename: Jianguo
authors.initials: J
authors.lastname: Zhu
authors.forename: Zubin
authors.initials: Z
authors.lastname: Xie
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.forename: Gaiping
authors.initials: G
authors.lastname: Chen
authors.forename: Yali
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000388:Air / Q000032:analysis*; D000596:Amino Acids / Q000096:biosynthesis; D002245:Carbon Dioxide / Q000032:analysis*; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000378:metabolism / Q000502:physiology*; D018517:Plant Roots / Q000378:metabolism / Q000502:physiology*; D052584:Xylem / Q000378:metabolism
chemical_list: D000596:Amino Acids; D002245:Carbon Dioxide; D009584:Nitrogen