Symbiotic And Phenotypic Characteristics Of

ABSTRACT: The ability of indigenous rhizobia to nodulate a legume crop effectively was critical to successful establishment and growth of legumes. This study was aimed to evaluate the symbiotic effectiveness along with growth responses to varied conditionslike pH, salt, temperature, antibiotics, and carbon and nitrogen sourcesfor rhizobial isolates nodulating faba bean from Tahtay Koraro, northwestern Zone of Tigray. For this matter, a total of thirty-six isolates of Rhizobium were isolated from as many sampling sites of Tahtay Koraro using plant infection method in Addis Ababa University, Applied Microbiology greenhouse.The isolates were characterized morphologically and physiologically and tested on sand to evaluate their symbiotic effectiveness.Results indicates that culturally almost all of them displayed large colonies with diameters of 2 to 4.5 mm, generation time of>3.91 hrs and showed characteristics of fast growing rhizobia.The symbiotic effectiveness results on sand culture indicated that, the isolates showed shoot dry matter ranging from 0.47 (AUFR-9) to 1.5 g/plant (AUFR-17), with negative control of 0.43 g/plant and positive control of 1.3 g/plant. All the tested isolates were able to grow well within the ranges of 6-9.5 and 15 0 C-35 0 C for pH and temperature, respectively. The highest and lowest nodule number score was 91 (AUFR-5) and 17 (AUFR-36), respectively. The preliminary screening of the authenticated isolates for symbiotic effectiveness on sand cultur