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Estimating symbiotic N 2 fixation in Robinia pseudoacacia
Author(s) -
Marron Nicolas,
Gana Cécilia,
Gérant Dominique,
Maillard Pascale,
Priault Pierrick,
Epron Daniel
Publication year - 2018
Publication title -
journal of plant nutrition and soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 1436-8730
DOI - 10.1002/jpln.201700503
Subject(s) - robinia , nitrogen fixation , locust , herbaceous plant , acacia , botany , isotope analysis , biology , isotopes of nitrogen , agronomy , nitrogen , chemistry , ecology , organic chemistry
Estimating symbiotic di‐nitrogen (N 2 ) fixation is challenging, especially when working with woody N 2 fixers in field trials. Fortunately, isotope methods based on 15 N natural abundance or on 15 N artificial enrichment (dilution method) make it possible to estimate the proportion of nitrogen derived from the atmosphere (Ndfa) in N 2 ‐fixing species. These methods have been extensively used in the field for herbaceous species, much less for tree species such as alder and acacia, and rarely for black locust ( Robinia pseudoacacia ). The objectives of this study were to characterize the fixation potential of black locust in a plantation by using the two 15 N isotope methods in the field, and to document values of isotope fractionation occurring during N 2 fixation (the B value). B values were estimated both by growing trees on an N‐free medium in controlled conditions ( B lab ) and by making Ndfa calculated with the natural abundance method converge with Ndfa calculated with the 15 N dilution method in the field ( B field ). The two methods gave consistent estimates of the B value. B values ranging between –1.4 and –3.2‰ were found, varying with the age of the plant material. Up to 76% of the N in the black locust trees came from the atmosphere, representing more than 45 kg N ha −1 over five years and confirming that black locust may be well adapted to N‐poor soils.