Effects of Rhizobium inoculation and variety on the Productivity of Soybean in Minna, southern Guinea savanna

Abstract

Crop genotype as well as the effectiveness of rhizobium inoculants affect productivity of legumes especially soybeans. A field experiment was conducted at the Teaching and Research farm, Federal University of Technology, Minna. The aim of the research was to quantify the contribution of elite strains of rhizobium to the growth and yield of promiscuous soybean varieties and to ascertain if there will be need for inoculation with these elite strains. The experimental design was a 3 x 5 x 4 factorial experiment fitted to Completely Randomized Design. The treatments were three N levels (0 Kg N ha-1, Peat inoculant, Total Nitro liquid inoculant) and five soybean varieties (TGX 1448-2E, TGX 1951-3F, TGX 1945-1F, TGX 1835-10F and local check). All treatments were replicated 4 times. Plots of size 3.5 x 4m were marked out with an inter-plot spacing of 1m and inter-rep spacing of 2m. Seeds were sown at the rate of 4 seeds per hole and thinned to 2 seedlings at one week after sowing, prior to basal application of 20 Kg N and 30 Kg P205 ha-1. Inoculation was done at the rate of 5g of peat per Kg of seeds and 28 mls of TotalNitro per Kg of seeds. Results revealed that inoculation and variety significantly affected shoot biomass and nodule weight of soybeans demonstrating that some benefits can be derived from inoculation of promiscuous soybean. Yield was not significantly affected by inoculation, suggesting that the indigenous strains were probably more competitive than the introduced rhizobia. Given the mixed results obtained from this preliminary field work, it is necessary to conduct a need-to-inoculate of soils across the Nigerian savanna to establish the frequency and magnitude of response to inoculation.