Cowpea (Vigna unguiculata L.) is one of the main food crops in the north and northeast of Brazil nowadays, being planted on large areas in other Brazilian regions as well, with bright prospects in the Brazilian agribusiness. Symbiosis of cowpea and nitrogen-fixing bacteria (NFB) can raise yields and decrease yield costs. The first aim of this study was to evaluate the agronomic efficiency of previously selected rhizobia strains compared to the strain recommended until 2004 (BR 2001). The phenotypic diversity of native rhizobia populations was evaluated by cultural characteristics and analysis of total protein profiles by polyacrylamide gel electrophoresis (SDS-PAGE). In field inoculations with strains UFLA 03-84 and INPA 03-11B grain yields increased similarly as in the control treatment with 70 kg ha-1 N-urea and outmatched the treatment with BR 2001 inoculation. Native cowpea-nodulating populations have a high phenotypic diversity and do not resemble the strains introduced as inoculants.
Vigna unguiculata; Bradyrhizobium; biological N2 fixation; yield
