Nodulation in Situ of Common Bean (Phaseolus vulgaris L.) And Field Outcome of an Elite Symbiotic Association in Senegal

The investigation of common bean rhizobial indigenous population in Senegal indicated a low rate of nodulation in field. However fifty eight rhizobial strains were isolated from root nodules of common be an ( Phaseolus v ulgaris) g rowing in soil sampled from various S enegalese localities. A n elite symbiotic ass ociation Rhizobium strain ISR A 355 x com mon be an vari ety Bronco was selected from the greenhouse experiment conducted at Bel Air experimental station. This efficient association was u sed in an experimental field c arried out at this station to a ssess effect of rhizobial inoculation on common be an. Inoculation with Rhizobium strain ISRA 355 and nitrogen fertilizer application (0, 20 or 80 kg N/ha) were significant on shoot and root dry weights mainly. However, pod yields and nodules dry weight were significantly higher in i noculated and nitrogen (20 kg N/ha) treated plots than in uninoculated: +77% and +300% respectively. Pod yield was highly i mproved (+77%) b y the interaction between inoculation with ISRA 355 and nitrogen fertilizer at 20 kg N/ha. Whatever the nitrogen rate was, inoculation of common bean incre ased the acetylene reduction a ctivity (+ 156%) i n c omparison to the uninoculated plants. Similarly in i noculated treatments, the rel ative ab undance of ur eide-N in plant s treated with 20 kg N/ha was h igher th an that o f p lants un fertilized or a mended with 80 kg N/ha for + 10% and +16% respectively.