Abstract:
Legumes form symbiotic relationship with some soil bacteria such as Rhizobia. The study
was designed to isolate, characterize and evaluate symbiotic effectiveness of Rhizobium
from root nodules of T.foenum graecum L. Three to five nodules per plant were collected
from six main T. foenumgraecum L.growing areas in Shebel Berenta in East Gojjam Zone.
Thirty root nodule samples were collected in glass vial containing silica gel and
transported to Holleta agricultural research center. The samples were preserved at room
temperature. The collected data were analyzed using SPSS version25 and Microsoft excel.
15. Rhizobium isolates were obtained by the aseptic Rhizobia presumptive and
confirmatory screening (YEMA-CR), (YEMA-BTB) tests and selected as candidates for
authentication. Those fast growers, gram-negative, rod shaped, culturally round shaped,
white milky and sticky mucoid regardless of colony size in the range of 2.8 to 4.3
mm.Cultures were maintained on (0.3%) YEMA slant and (40%) glycerol for further study
and field check. A total of 12 (80%) infective isolates out of 15 showed positive reactions
for catalase test, motility, starch hydrolysis test and gave a negative test result for urease.
But, vary in citrate utilization, gelatin liquefaction and Indole acetic acid production.
Isolates were showed a wide range of growth responses to temperature with maximum
value at 28±2oC (32.74%), salt (%w/v); 0.01(32.6%), pH; 6.5 (23.14%) and 6.8 (25.47%)
in 48 hours of incubation. Isolates were highly sensitive to antibiotics; levofloxacin,
gentamycin and chloramphenicol. The isolates utilized different carbon and nitrogen
sources. In vivo characterization of 15 isolates under green house conditions, showed
significant variations in symbiotic effectiveness JUWgR13 (50.58%), JUGyR53 (55.47%),
JUYwR23 (61.63%), JUWgR12 (63.39%) and JUWgR11 (105.65%). The numerical
analysis of the isolates on forty one phenotypic features and stastical analysis of symbiotic
infective characteristics showed the diversity across areas of collection and between
isolates.
