Inoculation of local cowpea varieties with selected rhizobia strains

Abstract

The efficient combination of cowpea variety and rhizobia strain is important to raise crop productivity. However, selected strains have not been tested with most of the varieties cultivated in the semiarid area of Northeast Brazil. To evaluate the efficiency of four recommended strains with six cowpea varieties cultivated in the Agreste region of Paraíba, a completely randomized factorial experiment, with three replications, was conducted in Leonard pots filled with sterilized substrate. Varieties "IPA 206", "Sedinha", "Corujinha", "Canapu", "Sempre Verde" and "Azul" were inoculated with BR 3267, BR 2001, EI 6 and NFB 700 strains, plus two treatments with, and without, N fertilizer. Plants were harvested 40 days after sowing. BR 3267 and BR 2001 strains produced the highest biomass, N concentrations and contents and nodule numbers. Inoculation with EI 6 resulted in poor plant performance, especially with variety IPA 206. Performance with NFB 700 was slightly better than with EI 6. Sedinha and Sempre Verde were the best varieties regarding biomass, N content and nodule numbers.