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VESICULAR‐ARBUSCULAR MYCORRHIZA IMPROVE BOTH SYMBIOTIC N 2 FIXATION AND N UPTAKE FROM SOIL AS ASSESSED WITH A 15 N TECHNIQUE UNDER FIELD CONDITIONS
Author(s) -
BAREA J. M.,
AZCÓNAGUILAR C.,
AZCÓN R.
Publication year - 1987
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1987.tb00172.x
Subject(s) - legume , biology , mycorrhiza , nitrogen fixation , symbiosis , agronomy , forage , arbuscular mycorrhiza , inoculation , dry matter , fertilizer , phosphorite , botany , horticulture , bacteria , genetics
S ummary A technique using 15 N‐labelled inorganic fertilizer was applied to estimate N 2 fixation by the forage legume Hedysarum coronarium L. and to ascertain the role of vesicular‐arbuscular (VA) mycorrhizas in plant N nutrition throughout a growing season under field conditions. The absence of the specific Rhizobium for the forage legume in the test soil allowed us the use of 15 N methodology with the same legume as reference ‘non‐fixing’ crop. At the first harvest, mycorrhizal inoculation behaved similarly to the phosphate addition in improving the percentage (70 %) and the total amount of N derived from fixation. But thereafter, mycorrhizal inoculation not only enhanced dry matter yield, N concentration and total N yield but also the amount of N derived from soil and from fixation, as compared with either phosphate‐added or control plants. This indicated that mycorrhizas acted both by a P‐mediated mechanism to improve N 2 fixation and by enhancing N uptake from soil. The latter agrees with recent findings by others that VA mycorrhizal hyphae can translocate and assimilate ammonium, a fact of physiological and ecological interest.