ISOLATION, BIOCHEMICAL CHARACTERIZATION, AND GREENHOUSE AUTHENTICATION OF CHICKPEA RHIZOBIA COLLECTED FROM MAJOR CHICKPEA GROWING AREAS OF WOLDIA.NORTH WOLLO, ETHIOPIA

Chickpea (Cicer arietinum L.) is a vital legume crop worldwide, valued for its high nutritional 
content and significant contribution to food security and soil fertility through biological nitrogen 
fixation. Despite its importance, chickpea yields remain suboptimal in many regions, including 
Ethiopia, primarily due to constraints such as poor soil fertility and inadequate use of effective 
rhizobial inoculants. Biological nitrogen fixation by symbiotic Rhizobium bacteria plays a 
crucial role in enhancing chickpea productivity, yet the diversity and effectiveness of native 
rhizobia in the Woldia area remain poorly understood. This study aimed to isolate and 
characterize native Rhizobium strains from chickpea root nodules collected from fields in the 
Woldia region and to assess their plant growth-promoting potential. A total of 41 bacterial 
isolates were obtained, of which 12 were presumptively identified as Rhizobium based on growth 
characteristics on Congo red and bromothymol blue media. These isolates were further 
characterized morphologically and biochemically. All confirmed isolates were Gram-negative, 
rod-shaped, motile, and exhibited positive reactions for oxidase, catalase, urease, starch 
hydrolysis, ammonia production, citrate utilization, and nitrogen fixation, while testing negative 
for indole production and gelatinase activity. Five biochemically promising isolates were 
selected for evaluation in a controlled 45-day greenhouse experiment under sterile conditions. 
Inoculation with these isolates significantly enhanced seed germination and early seedling 
growth compared to uninoculated controls. The symbiotic effectiveness of the isolates ranged 
from 74.3% to 121.9%, with isolates SFDG-23, SFMC-31, and SFMC-23 demonstrating high 
effectiveness. Particularly, isolate SFDG-23 markedly increased nodulation and biomass 
accumulation. Although morphological and biochemical characterization provided useful 
preliminary identification, it alone cannot confirm the taxonomic status of the isolates. 
Therefore, further molecular characterization is recommended. Moreover, field trials are 
necessary to validate the performance of the most promising isolates under natural growing 
conditions. In conclusion, this study highlights the potential of native Rhizobium isolates from 
Woldia chickpea fields, especially SFDG-23, as effective bio-inoculants to promote sustainable 
chickpea production and reduce dependence on chemical fertilizers around woldia.