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Yield and N Content of Soybean Seed as Influenced by Rhizobium japonicum Inoculants Possessing the Hydrogenase Characteristic 1
Author(s) -
Hanus F. Joe,
Albrecht Steve L.,
Zablotowicz Robert M.,
Emerich David W.,
Russell Sterling A.,
Evans Harold J.
Publication year - 1981
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1981.00021962007300020028x
Subject(s) - microbial inoculant , inoculation , bradyrhizobium japonicum , loam , nitrogen fixation , biology , agronomy , rhizobiaceae , horticulture , bacteria , symbiosis , soil water , ecology , genetics
Rhizobium japonicum strains possessing the hydrogenase characteristic (Hup + ) are capable of forming nodules that recycle the H 2 produced during N 2 fixation. Experiments were conducted to compare seed yield and N content of soybcan ( Glycine max (L.) Merr.) inoculated with Hup + and Hup ‐ strains under field conditions. Hup + wild‐type strains (USDA 143, USDA 6, USDA 122, USDA 110, USDA 136, and SR), H 2 uptake negative (Hup − ) wild‐type strains (USDA 117, USDA 135, USDA 120, and USDA 16) and Hup − mutants (SR2 and SR3, derived from Hup + SR) were used as inoculants. Chehalis silt loam (mesic Cumulic Ultic Haploxeroll) and Ephrata loamy fine sand (mesic Xerollic Camborthid) relatively free of indigenous R. japonicum were used in the experiments. Bacteroid H 2 uptake rates and H 2 evolution from nodules from inoculated plots indicated no appreciable mixing among treatments. The inoculants applied to these relatively high N soils did not significantly affect seed yield, however, plants inoculated with the Hup + strains appeared greener, matured later, and in all four experiments produced seed with significantly higher N percentage than plants inoculated with groups of Hup − strains. Average data from all four exepriments showed that Hup + inoculants increased crude seed protein 8.9%. These results provide further evidence that R. japonicum inoculants for soybeans should possess the capacity to oxidize H 2 produced as a by‐product of N 2 fixation.