Estimates of n(2) fixation based on differences in the natural abundance of N in nodulating and nonnodulating isolines of soybeans.
Estimates of n(2) fixation based on differences in the natural abundance of N in nodulating and nonnodulating isolines of soybeans.
复制标题
基于大豆结瘤和非结瘤等系中氮自然丰度差异的 n(2) 固定估计。
作者：
D. Kohl;G. Shearer;J. E. Harper
在各种条件下生长的大豆（Glycine max（L）梅里尔，variety Harosoy）的生物固定氮对总氮的贡献的估计是由以下两个方面得出的：（a）生物固定和非生物固定等值线之间的氮产量差异;（B）两个等值线之间的氮丰度差异。对于生长在温室中营养贫乏土壤中的植物，两种估计都显示出高水平的N（2）固定; 58%至89%的N通过N产量的差异固定，51%至95%通过（15）N丰度的差异固定。两种方法都估计随着添加NO（3）（-）水平的增加，固定N的贡献减少。在未经改良的中西部高肥力土壤上进行的两年多田间试验结果表明，两种方法的N（2）固定水平都不高（N产量差异为7.3%至51%，（15）N丰度差异为5.4%至46%）。当土壤中添加玉米穗轴时，两种方法对固定氮的贡献率都较高。估计N（2）固定的两种方法给出了类似的结果。两者似乎都是半定量的，估计值的标准误差大致相同（平均为6%）。
Estimates of the contribution of biologically fixed N to the total N of nodulating soybeans (Glycine max (L) Merrill, variety Harosoy) grown under a variety of conditions were made from: (a) differences in N yield between nodulating and nonnodulating isolines; and (b) differences in (15)N abundance between the two isolines. For plants grown in a greenhouse in nutrient-poor soil, both estimates showed a high level of N(2) fixation; from 58 to 89% N fixed by differences in N yield and from 51 to 95% by differences in (15)N abundance. Decreasing contributions of fixed N were estimated by both methods with increasing levels of added NO(3) (-). Results of field experiments carried out over two years on an unamended highly fertile midwestern soil showed a modest level of N(2) fixation by both methods (7.3 to 51% by differences in N yield, and 5.4 to 46% by differences in (15)N abundance). When the soil was amended with ground corn cobs, both methods showed higher contributions of fixed N. The two methods of estimating N(2) fixation gave similar results. Both appear to be semiquantitative and the standard errors of the estimates were about the same (6% on the average).