【摘要】 采用稳定性同位素15N自然丰度(15N natural abundance)技术,以小麦为参照植物,研究了盆栽条件下,在外源供氮0、0.8、2.0、4.0 mmol·L-1水平下大豆的生物固氮百分率以及生物固氮数量对植物氮的贡献.结果显示:(1)0~2.0 mmol·L-1外源供氮可显著提高大豆的生物量和固氮百分率,且于2.0 mmol·L-1处理下地上生物量最高,达104 g·m-2,比CK增加了48%;(2)在0.8 mmol·L-1的供氮水平下大豆生物固氮量最高,为1.318 g·m-2,占大豆植株总吸氮量的70.4%,而在4.0 mmol·L-1供氮水平下生物固氮量仅占植株总吸氮量的44%;随供氮水平的升高,大豆生物固氮量占总吸氮量的比重下降,说明在高水平外源氮下,大豆生物固氮能力受到抑制;(3)大豆生物固氮百分率、固氮数量及吸氮数量与地上生物量间均呈显著正相关关系.结果表明,应用稳定性15N同位素技术可以定量大豆的生物固氮效率,根瘤菌接种配合低浓度外源氮有利于大豆生物固氮潜能的释放,对提高大豆产量、减少化肥投入有积极的指导意义.更多还原

【Abstract】 A pot experiment was conducted to determine the BNF(biological nitrogen fixation) ability of soybean [Glycine max(Linn.) Merr.] under 0,0.8,2.0,4.0 mmol N·L-1 levels nitrogen supply.The percentage nitrogen fixation rate(%Ndfa) was tested by MAS isotope spectrometer.Spring wheat was used as reference plant.The results showed that soybean biomass was significantly increased with the supplied N level at range 0 to 2.0 mmol·L-1.The aboveground biomass at 2.0 mmol·L-1 nitrogen supplied was up to 104 g·m-2,48% increase than that of CK;The N2 fixation amount in soybean was the highest when the supplied N concentration was at 0.8 mmol·L-1,some 1.318 g·m-2 was fixed,amounted to 70% of total soybean N uptake,BNF ability was shown to be restricted at supplied N levels above 4.0 mmol·L-1.Significantly positive linear relationships among %Ndfa,amount of N fixed,plant N uptake and aboveground biomass were found.It conclude that N2 fixation amount in soybean can be assessed using 15N natural abundance method,the BNF ability was weaken when additional N supply increased.更多还原