The relationship between N isotopic fractionation within soybean and N2 fixation during soybean development. Issue 3 (22nd May 2014)

• Record Type: Journal Article
• Authors: Schweiger, Peter; Hofer, Michaela; Vollmann, Johann; Wanek, Wolfgang
• Is Part Of: Physiologia plantarum. Volume 152:Issue 3(2014:Nov.)
• Page Start: 546
• Page End: 557
• Publication Date: 2014-05-22
• Subjects: Plant physiology -- Periodicals; 571.2
• DOI: 10.1111/ppl.12204
• Languages: English
• ISSNs: 0031-9317

Abstract

<abstract abstract-type="main" id="ppl12204-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="ppl12204-para-0001">The contribution of N<sub>2</sub> fixation to overall soybean N uptake has most commonly been quantified by N isotope‐based methods, which rely on isotopic differences in plant N between legumes and non‐fixing reference plants. The choice of non‐fixing reference plants is critical for the accuracy of isotope‐based methods, and mismatched reference plants remain a potential source of error. Accurate estimates of soybean N<sub>2</sub> fixation also require information on N isotopic fractionation within soybean. On the basis of a previous observation of a close correlation between an expression of N fractionation within soybean and the proportion of plant N derived from atmosphere (%Ndfa) determined by <sup>15</sup>N natural abundance, this field study aimed at assessing the relationship between various expressions describing intraplant <sup>15</sup>N or N partitioning and %Ndfa during soybean development. Starting from a late vegetative stage until beginning senescence, the N content and N isotopic composition of shoots, roots and nodules of nodulated and non‐nodulated soybeans was determined at eight different developmental stages. Regression analysis showed that %Ndfa most closely correlated with the difference in the N isotopic composition of shoot N minus that of root including nodule N, and that this relationship was similar to that obtained in a previous multi‐site field study. We therefore consider this expression to hold promise as a means of quantifying %Ndfa independent of a reference plant, which would avoid some of the external sources of error introduced by the use of reference plants in determining %Ndfa.</p> </abstract>