Effects Rhizobium strains on Cowpea cultivars from the agreste region of Paraiba

by Lucena Vieira, Carolina de

The response of local cowpea cultivars to inoculation with recommended rhizobia strains has not been well established yet. Four rhizobia strains (BR2001, BR3267, EI6 andNFB700) were tested with six cowpea cultivars (Sedinha, Corujinha, Canapu, Sempre verde, Azul and IPA-206) traditionally planted in the Agreste of Paraíba. Leonard pots with sterilized substrate were used under greenhouse conditions. Plants were harvested 40 days after germination. BR 3267 and BR 2001 were the most effective strains with all varieties, resulting in higher nodulation and N concentrations and contents than those obtained with EI 6 and NFB 700. However, in relation to plant biomass, only BR 2001 differed significantly from the last two strains. EI 6 and NFB 700 promoted positive responses only on two Sedinha variables: nodule number and aboveground plant biomass. IPA-206 did not nodulate with EI 6 and showed the lowest biomasses and N concentrations and contents. In general, Sempre Verde and Sedinha were the varieties with the best results, specially the former due to its good responses to inoculation with all strains