It evaluates the effect of inoculation with two rhizobia strains isolated from soils under rehabilitation after bauxite mining: UFLA 3-164 and UFLA 3-155, compared to inoculation with strains INPA 03 11B (BR 3301); UFLA 03 84 (BR 3302) and BR 3267 (SEMIA 6462), officially authorized as inoculant to cowpea by MAPA, in Vigna unguiculata (L.) Walp cv. "BR 17 Gurgueia". The experiment was carried out at the 'Universidade Federal do Piauí, Campus Professora Cinobelina Elvas, Bom Jesus, PI,' in a randomized block design, white seven treatments and six replications. Treatments were the five strains and two controls: one receiving mineral N (70 kg ha-1 de N) and the other an absolute control. Nodule number and dry matter weight, shoot dry matter weight, grain yields and N-content both in shoots and grain were evaluated. The inoculation of the seeds with diazotrophic symbiotic bacterial strains resulted in the improvement of yields equivalent and/ or superior to the control receiving mineral nitrogen. The strain UFLA 3-155 has presented a grain yield similar to one of MAPA recommended strains, INPA 03 11B (BR 3301) and can also be tested in other brazilian regions. Among the strains recommended by MAPA, the INPA 03 11B (BR 3301) produced the higher yields.
Brandyrhizobium; Fixation of N2; Legumes
