Pages: (1-12 )
Abstract
Biological Nitrogen Fixation is one of the major sources of nitrogen in inherently low tropical soil. Microbial resistances to varying concentrations of antibiotics can be a factor for determining their degree of tolerance to environmental stress. Use of carriers for inoculant preparation facilitates survival and multiplication of rhizobium strains (microbes). Parent rhizobium strains USDA 3384 and USDA 3451 were exposed to antibiotics at different concentrations to determine their intrinsic resistance levels, which were further seeded into three different solid carriers (Peat, composted maize cob and cowdung). Mutant strains inoculated with or without solid carriers were investigated using laboratory and pot experiments. Their effect on growth and dry matter yield of cowpea (Ifebimpe) were assayed, while data collected was analysed using ANOVA, means were separated using Duncan Multiple Range Test (DMRT) at 5 % probability level. USDA 3384 and USDA 3451 were resistant to Ampicillin trihydrate pensy at 500 mg/l and Streptomycin sulphate at 1000 mg/l respectively. Solid carriers used significantly and positively influenced (p<0.05) the various parameters evaluated compared to mutant strains inoculated without solid carriers. The strains investigated responded differently to various concentrations of antibiotics used which shows the ability of strains to survive in varying environmental stress.
Keywords: Antibiotics, Bradyrhizobium, Cowpea, Growth, Solid-carrier.,