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Teores de leg-hemoglobina e de molibdênio nos nódulos de soja (Glycine max) inoculada com estirpes de Rhizobium japonicum de eficiência normal e excepcional

1970; Embrapa Informação Tecnológica; Volume: 5; Issue: 1 Linguagem: Inglês

1678-3921

Fábio de Oliveira Pedrosa, Aguinaldo José do Nascimento, Roberto Alvahydo, Johanna Döbereiner,

Soybean genetics and cultivation

Two greenhouse experiments were carried out in sterilized Leonard jars with four soybean varieties inoculated with a Rhizobium strain considered normal (SM1b) and another with exceptional efficiency (R54a), to study the correlation of leghemoglobin and molybdenum content of the nodules and nitrogen fixation. Nitrogen fixation per unit nodule weight as evaluated by the regression of total plant nitrogen with nodule weight (Fig. 1) was about twice as high with the exceptional strain. The increase in molybdenum content was correspondent to the higher nodule efficiency being twice as high in nodules formed by the exceptional strain. It was thus suggested these nodules having doubled nitrogenase content. The increase in leghemoglobin content, however, was not correspondent to the increase in nodule efficiency. An increase of 136% in average of the nodule efficiency was accompanied by an increase of only 27% of the leghemoglobin content (Table 1, Fig. 2). Within strains there was no correlation of either molybdenum or leghemoglobin content with nodule efficiency. It was therefore suggested that for each group of strains nitrogenase and hemoglobin content in nodules and nodule efficiency are theoretically constant, variations being due to the experimental error. The difference between normal and exceptional strains of Rhizobium japonicum would then be due to a difference in the nitrogen fixing system or in the mechanism of incorporation of NH 3 .