Interactions of nitrate-reductase and nitrogenase activities in maize genotypes

• Autor(a) principal: Baldani, José Ivo
• Data de Publicação: 2014
• Outros Autores: Blana, Roberto Antonio Goic, Dobereiner, Johanna
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Pesquisa Agropecuária Brasileira (Online)
• Texto Completo: https://seer.sct.embrapa.br/index.php/pab/article/view/16676
• topic: maize; nitrogen; fixation; nitrato reductase; genotype; milho; nitrogênio; fixação; nitrato-redutase; genótipo

In two field experiments the effects of plant genotype on the interaction of nitrogenase activity (N2-ase) in roots and nitrate-reductase activity (NR) in leaves were studied. Higher nitrogenase activities in the cultivar Piranão thon in UR-I were confirmed, but one cycle of massal selection for high N2-ase was not effective. Lines of UR-I in S2 selection for high and low N2-ase, on the other hand, showed significant differences. In both experiments N2-ase activity in roots showed negative correlations with NR in leaves, even when plant genotype was the only source of variance. The slope of these regressions, that is, the proportion of increase of N2-ase with decreasing NR varied with age of the plant and nitrogen level in soil. The grain yield of both cultivars did not differ significantly. Nitrogen applications were significant only at the 40 kg/ha level. The results of the paper indicate that maize breeding for increased nitrogen fixation should include studies on the interactions of nitrate assimilation to permit selection of maize genotypes which permit complementation of nitrogen fixation with nitrogen fertilizers.