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Biological nitrogen fixation associated with roots of field‐grown barley (Hordeum vulgare L.)
Author(s) -
Idris Mohammad,
Vinther F. P.,
Jensen V.
Publication year - 1981
Publication title -
zeitschrift für pflanzenernährung und bodenkunde
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 87
eISSN - 1522-2624
pISSN - 0044-3263
DOI - 10.1002/jpln.19811440407
Subject(s) - rhizosphere , hordeum vulgare , nitrogen fixation , nitrogenase , inoculation , nitrogen , chemistry , agronomy , botany , biology , horticulture , poaceae , bacteria , genetics , organic chemistry
Nitrogenase (C 2 H 2 ) activity was measured in microbial media inoculated with barley root segments or corresponding rhizosphere soil. Three different media were used, Döbereiner's malate medium, a modified Ashby medium, and an acid nitrogen‐free medium. Only Döbereiner's medium gave consistently positive results, and cultures inoculated with roots showed higher activity than cultures inoculated with corresponding rhizosphere soil. Similar experiments with roots and rhizosphere soil from wheat gave only negligible nitrogenase activity, whereas the tropical grass, Cynodon dactylon , gave higher activity than barley. Measurements on intact soil cores containing barley root systems showed an initial lag phase followed by a rather stable activity level over a period from 12 h to 48 h, and then the activity again decreased. The activity during the stable period corresponded to fixation of about 100 to 200 g N 2 ha −1 24 h −1 . Measurements on isolated, washed barley roots showed only negligible nitrogenase activity.