Contribution of biological nitrogen fixation to cowpea: a strategy for improving grain yield in the semi-árid region of Brazil.

• Autor(a) principal: MARTINS, L. M. V.
• Data de Publicação: 2003
• Outros Autores: XAVIER, G. R., RANGEL, F. W., RIBEIRO, J. R. A., NEVES, M. C. P., MORGADO, L. B., RUMJANEK, N. G.
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA - Alice)
• Texto Completo: http://www.alice.cnptia.embrapa.br/alice/handle/doc/152219
• topic: Caupi; Competitividade; Região semi-árida; Rope bean; Feijão de corda; Fixação de Nitrogênio; Produtividade; Rhizobium; Vigna Unguiculata; Cowpeas

Nodulating bacteria from the famaly Rhizobiaceae are common in the semi-arid tropics around the world. The brazilian semi-arid region extends over 95 million hectares of which only 3% is suitable for irrigation, therefore leaving an immense dryland area to be exploited by peasant farmers, who often lack appropriate technologies for sustainable management. Cowpea is an impoertant crop in this area, representing the staple protein source for human nutrition. This work aimed to identify rhizobial strains capable of guaranteeint sufficient nitrogen derived from biological fixation fpr cowpea cultivated in dryland areas, evaluating not just efficiecy but also the ecological parameters of competitiveness and survival in the soil. Grain yield and nodulation parameters showed that strain BR 3267 is capable of stablishing efficient nodulation, improving both yield and total N accumulated in grain. Cowpea inoculated with strain BR 3267 showed grain productivity similar to plants receiving 50 kg of N per hectare, which is the amount of fertilizer commonly used in the North-east region. These characteristics associated with previously determined ecological properties makes strain BR 3267 an important resource for the optimization of biological nitrogen fixation in cowpea in the dryland areas of the semi-arid tropics. Data on the dynamics of rhizzobizl populations in such areas have shown that (1) the naturalized rhizobium population is very small and, by themselves, do not promote proper nodulation and, (2) the inoculant rhizobia do not persist between crops. Such characteristics represent an opportunity for the introduction of superior rizhobia strains, such as BR 3267, during the cowpea crop.