【摘要】 利用FACE(FreeAirCarbon-dioxideEnrichment)平台技术,用伤流量法研究了低氮(LN150kg.hm-2)和常氮(NN250kg.hm-2)水平下,大气CO2浓度升高对水稻分蘖、抽穗期和穗后35d根系活力和根系N同化能力(氨基酸合成能力)的影响.结果表明,就整株水稻来看,CO2浓度升高和N处理对根系活力无显著影响;但由于FACE条件下水稻分蘖数增加14.5%(LN)和20.7%(NN),使每茎根系活力(伤流强度)降低1.4%~21.7%.在分蘖和抽穗期,虽然FACE处理促进了根系吸收的无机N向氨基酸转化,根系伤流液中氨基酸氮/无机氮提高11.1%~143.1%,但氨基酸浓度和合成总量和对照相比无明显差异.在穗后35d,FACE处理减弱了水稻根系的N同化能力,表现为根系伤流液中氨基酸/无机氮降低38.1%(LN)和29.2%(NN);同时氨基酸浓度降低34.0%(LN)和44.7%(NN),氨基酸合成总量降低50.8%(LN)和40.0%(NN).提高施氮水平促进了抽穗期水稻根系对无机氮的吸收,伤流液中无机氮含量增加51.1%(对照)和155.2%(FACE),但并未增加氨基酸合成量,由此导致抽穗期氨基酸氮/无机氮显著降低19.5%(对照)和36.8%(FACE);同时,氮处理在这个时期与FACE处理表现出明显的交互作用.更多还原

【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 kgNhm^-2)and normal N(NN,250 kgNhm^-2)under ambient air and elevated atmospheric CO₂(Ambient+200 μmolmol^-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 CO₂N interaction on aa N/inorganic N at heading stage.更多还原