Growth and yield of the cowpea cultivar BRS Guariba inoculated with rhizobia strains in southwest Piauí

Abstract

The interaction of cowpea with efficient strains of rhizobia in biological nitrogen fixation can allow increased yield, which can completely replace nitrogen fertilization and can reduce production costs. The aim of this study was to evaluate the response of cowpea cultivar BRS Guariba to inoculation with six strains of rhizobia (UFLA 03-164, UFLA 03-154, INPA 03-11B, UFLA 03-84, BR 3267 and BR 3262) in a field experiment conducted in the Southwest of Piauí. The experimental design was randomized blocks with eight treatments and four replicates, including the six cited strains and two uninoculated controls, one with mineral nitrogen (70 kg ha-1) and the other without mineral nitrogen. Nodulation, growth, yield, nitrogen accumulation in shoots and in grains and crude protein content in grains were evaluated. Strains under selection (UFLA 03-154 and UFLA 03-164) promoted yields that were higher compared to those obtained by strains authorized as inoculants (INPA 03-11B, BR 3267 and BR 3262). Inoculation with strains UFLA 03-84, UFLA 03-154 and UFLA 03-164 promoted yields equivalent to the control with mineral nitrogen (796.51 kg ha-1) and similar to the yield obtained with the control without mineral nitrogen and without inoculation, indicating efficient symbiosis of the indigenous rhizobia. UFLA 03-154 was better than the other treatments in terms of increased crude protein.