| dc.description.abstract | A study to characterise indigenous rhizobia nodulating bean (Phaseolus vulgaris L) was conducted from April, 2018 to November, 2018 in Hai District. Thirty rhizobia organisms were isolated from bean root nodules and grown on Yeast Extract Mannitol Agar containing Congo Red (YEMA w/Congo Red). Morphological identification and molecular characterization based on 16srRNA and gyrase subunit B (gyrB) genes and evaluation of the rhizobia isolates for their symbiotic effectiveness on bean was conducted. The results showed that all rhizobia isolates were fast growing (2 – 5 days) on YEMA w/congo red, failed to absorb Congo Red, and displayed whitish or creamy colour on Yeast Manitol Broth (YMB) indicating that they were rhizobia. Results also showed that DNAs from 18 out of 30 rhizobia isolates were amplified by 16S rRNA primers, and only 9 out of 30 rhizobia isolates were amplified by gyrase subunit B primers. DNAs from eight of the isolates were neither amplified by 16S rRNA nor gyrB primers indicating they were different from those that the primers could amplify. Nevertheless, in testing the effectiveness, all 30 isolates were able to induce nodules on host plant and most of them had relative effectiveness index (RI) which was as high as that of the commercial CIAT 899 strain. Isolate IR1, IR3, IR10 and IR12 had RI above 100%, higher than CIAT 899. Isolate IR20 had the lowest HI (78%). Such results implied that indigenous rhizobia identified can be used for bean inoculation instead CIAT 899 in Tanzania. | en_US |
