Field evaluation of symbiotic nitrogen fixation by rhizobial strains using15N methodology
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Small differences in N2 fixation by nodulated soybeans (Glycine max. (L.) Merr.), inoculated with various strains ofRhizobium japonicum, were assessed in field experiments using15N methodology, and compared with yields of plant dry matter and total N. Percentage of plant-N derived from atmospheric N2 and from fertilizer, and values of %15N atom excess had lower coefficients of variation than did total N and dry matter yield. Nevertheless the precision of estimates of kg N/ha fixed were sufficient to differentiate only the extremes of the range of strains tested, and there were discrepancies between ranking of strains based on % N derived from fertilizer and on total N yield.
Key wordsGlycine max. (L.) Merr. N2-fixation 15N methodology N yield Rhizobium japonicum Soybean
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