Suitability of indigenous rhizobia isolates as nitrogen biofertilizers for groundnut in the Nigerian Savanna

A study was conducted in search of the best inoculant for recently released groundnut genotypes in the Nigerian Savana. The treatments were two (2) groundnut genotypes (SAMNUT 25 and SAMNUT 26) and five (5) nitrogen (N) sources; (NC 92; KBU 026; MJR 518; optimum N and uninoculated control). These were factorially combined into a total of 10 treatment combinations replicated three times in a randomized complete block design (RCBD). The plants were grown for six (6) weeks and the number of flowers, shoot dry matter and N uptake were determined. The results showed significant difference among the treatments and their interactions (P < 0.05), with respect to all parameters. These were used to arrive at the best inoculant in terms of N2 fixation in symbiosis with SAMNUT 25 as KBU 026, while MJR 518 had higher capacity of N2 fixation in symbiosis with SAMNUT 26. Even though, KBU 026 generally performed better than the latter relative to both groundnut genotypes. The study indicates variation among indigenous rhizobia isolates for suitability as potential inoculants for groundnut inoculation. It also shows the possibility of arriving at a best inoculant (KBU 026) for both genotypes.