Symbiosis between Rhizobium and legumes are a cheaper and usually more effective agronomic practice for ensuring an adequate supply of nitrogen for legume based crop and pasture production than the application of nitrogen fertilizer. Crolotalaria ocroleuca is one of the members of crotalaria grown as cover crop or inter crop in southern and south western parts of Ethiopia. Nineteen isolates were isolated from the root nodules of Crolotalaria ocroleuca from coffee growing area in Godere Wereda, Gambella region. Presumptive tests and microscopic features confirmed that the isolates were rod shaped and gram-negative rhizobia. Based on colony and growth characters the isolates were grouped into two groups. Accordingly, 15 isolates were fast growing and acid producing Rhizobium spp; whereas four isolates (AAUCR4. AAUCR9, AAUCR14 and AAUCR18) were slow growing and alkali producing Brady rhizobium spp. Most of the isolates utilized the carbohydrates; sorbitol, xylose, and lactose, whereas only 26% and 15% were able to utilize starch and Na-citrate, respectively. All isolates were resistant to kanamycin and erythromycin at lower concentration of 2.5 and 5 µm/ml. Only 68% and 79% were résistance at (2.5 µm/ml) and 63% and 16% of the isolates were resistant at (5 µm/ml) to neomycin and gentamycin, respectively whereas isolates (AAUCR9 and AAUCR18) were resistant to all the tested antibiotics. The isolates also showed variability in their physiological characteristics. All isolates grew at 30°C. while, 63% and 53% of the isolates were able to tolerate 15°C and 40°C respectively. All isolates were able to grow at lower salt concentration (1-2%), and five isolates (26%) showed tolerance up to 4%. Only isolate (AAUCR9) was considered highly osmo-tolerant since it grew at 5% of salt concentration. Amongst the isolates, 21% were able to form clear zones around their colonies on Pikovaskaya’s medium and hence, they were considered as phosphate solubilisers with solubilisation index ranging from (2.2 -3). Relative effectiveness of the isolates was calculated by dry mass of the inoculated plant over the dry mass of positive control has significant difference within and among the treatment and positive and negative control at (p<0.05 Tukey’s test HSD) and accordingly, 47%, and 32%, of the isolates (79%) were highly effective (80-100%), and effective (50-80%) in nitrogen fixation. Generally, with over all competency analysis measurement two isolates AAUCR9 and AAUCR18 were the best isolates in terms of effective nitrogen fixation and tolerance to various ecological features that could make them competent against prospective candidates under field conditions.
| Published in | Frontiers in Environmental Microbiology (Volume 11, Issue 2) |
| DOI | 10.11648/j.fem.20251102.13 |
| Page(s) | 36-51 |
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Cultural Characters, Gambella, IAR, pH Tolerance, Symbiotic Effectiveness
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APA Style
Jarra, A. (2025). Symbiotic Properties of Rhizobium from Crotalaria Ocroleuca Used for Intercropping in CoffeePlantations in South-West Ethiopia. Frontiers in Environmental Microbiology, 11(2), 36-51. https://doi.org/10.11648/j.fem.20251102.13
ACS Style
Jarra, A. Symbiotic Properties of Rhizobium from Crotalaria Ocroleuca Used for Intercropping in CoffeePlantations in South-West Ethiopia. Front. Environ. Microbiol. 2025, 11(2), 36-51. doi: 10.11648/j.fem.20251102.13
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Download@article{10.11648/j.fem.20251102.13,
author = {Animaw Jarra},
title = {Symbiotic Properties of Rhizobium from Crotalaria Ocroleuca Used for Intercropping in CoffeePlantations in South-West Ethiopia
},
journal = {Frontiers in Environmental Microbiology},
volume = {11},
number = {2},
pages = {36-51},
doi = {10.11648/j.fem.20251102.13},
url = {https://doi.org/10.11648/j.fem.20251102.13},
eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.fem.20251102.13},
abstract = {Symbiosis between Rhizobium and legumes are a cheaper and usually more effective agronomic practice for ensuring an adequate supply of nitrogen for legume based crop and pasture production than the application of nitrogen fertilizer. Crolotalaria ocroleuca is one of the members of crotalaria grown as cover crop or inter crop in southern and south western parts of Ethiopia. Nineteen isolates were isolated from the root nodules of Crolotalaria ocroleuca from coffee growing area in Godere Wereda, Gambella region. Presumptive tests and microscopic features confirmed that the isolates were rod shaped and gram-negative rhizobia. Based on colony and growth characters the isolates were grouped into two groups. Accordingly, 15 isolates were fast growing and acid producing Rhizobium spp; whereas four isolates (AAUCR4. AAUCR9, AAUCR14 and AAUCR18) were slow growing and alkali producing Brady rhizobium spp. Most of the isolates utilized the carbohydrates; sorbitol, xylose, and lactose, whereas only 26% and 15% were able to utilize starch and Na-citrate, respectively. All isolates were resistant to kanamycin and erythromycin at lower concentration of 2.5 and 5 µm/ml. Only 68% and 79% were résistance at (2.5 µm/ml) and 63% and 16% of the isolates were resistant at (5 µm/ml) to neomycin and gentamycin, respectively whereas isolates (AAUCR9 and AAUCR18) were resistant to all the tested antibiotics. The isolates also showed variability in their physiological characteristics. All isolates grew at 30°C. while, 63% and 53% of the isolates were able to tolerate 15°C and 40°C respectively. All isolates were able to grow at lower salt concentration (1-2%), and five isolates (26%) showed tolerance up to 4%. Only isolate (AAUCR9) was considered highly osmo-tolerant since it grew at 5% of salt concentration. Amongst the isolates, 21% were able to form clear zones around their colonies on Pikovaskaya’s medium and hence, they were considered as phosphate solubilisers with solubilisation index ranging from (2.2 -3). Relative effectiveness of the isolates was calculated by dry mass of the inoculated plant over the dry mass of positive control has significant difference within and among the treatment and positive and negative control at (p<0.05 Tukey’s test HSD) and accordingly, 47%, and 32%, of the isolates (79%) were highly effective (80-100%), and effective (50-80%) in nitrogen fixation. Generally, with over all competency analysis measurement two isolates AAUCR9 and AAUCR18 were the best isolates in terms of effective nitrogen fixation and tolerance to various ecological features that could make them competent against prospective candidates under field conditions.
},
year = {2025}
}
TY - JOUR T1 - Symbiotic Properties of Rhizobium from Crotalaria Ocroleuca Used for Intercropping in CoffeePlantations in South-West Ethiopia AU - Animaw Jarra Y1 - 2025/06/12 PY - 2025 N1 - https://doi.org/10.11648/j.fem.20251102.13 DO - 10.11648/j.fem.20251102.13 T2 - Frontiers in Environmental Microbiology JF - Frontiers in Environmental Microbiology JO - Frontiers in Environmental Microbiology SP - 36 EP - 51 PB - Science Publishing Group SN - 2469-8067 UR - https://doi.org/10.11648/j.fem.20251102.13 AB - Symbiosis between Rhizobium and legumes are a cheaper and usually more effective agronomic practice for ensuring an adequate supply of nitrogen for legume based crop and pasture production than the application of nitrogen fertilizer. Crolotalaria ocroleuca is one of the members of crotalaria grown as cover crop or inter crop in southern and south western parts of Ethiopia. Nineteen isolates were isolated from the root nodules of Crolotalaria ocroleuca from coffee growing area in Godere Wereda, Gambella region. Presumptive tests and microscopic features confirmed that the isolates were rod shaped and gram-negative rhizobia. Based on colony and growth characters the isolates were grouped into two groups. Accordingly, 15 isolates were fast growing and acid producing Rhizobium spp; whereas four isolates (AAUCR4. AAUCR9, AAUCR14 and AAUCR18) were slow growing and alkali producing Brady rhizobium spp. Most of the isolates utilized the carbohydrates; sorbitol, xylose, and lactose, whereas only 26% and 15% were able to utilize starch and Na-citrate, respectively. All isolates were resistant to kanamycin and erythromycin at lower concentration of 2.5 and 5 µm/ml. Only 68% and 79% were résistance at (2.5 µm/ml) and 63% and 16% of the isolates were resistant at (5 µm/ml) to neomycin and gentamycin, respectively whereas isolates (AAUCR9 and AAUCR18) were resistant to all the tested antibiotics. The isolates also showed variability in their physiological characteristics. All isolates grew at 30°C. while, 63% and 53% of the isolates were able to tolerate 15°C and 40°C respectively. All isolates were able to grow at lower salt concentration (1-2%), and five isolates (26%) showed tolerance up to 4%. Only isolate (AAUCR9) was considered highly osmo-tolerant since it grew at 5% of salt concentration. Amongst the isolates, 21% were able to form clear zones around their colonies on Pikovaskaya’s medium and hence, they were considered as phosphate solubilisers with solubilisation index ranging from (2.2 -3). Relative effectiveness of the isolates was calculated by dry mass of the inoculated plant over the dry mass of positive control has significant difference within and among the treatment and positive and negative control at (p<0.05 Tukey’s test HSD) and accordingly, 47%, and 32%, of the isolates (79%) were highly effective (80-100%), and effective (50-80%) in nitrogen fixation. Generally, with over all competency analysis measurement two isolates AAUCR9 and AAUCR18 were the best isolates in terms of effective nitrogen fixation and tolerance to various ecological features that could make them competent against prospective candidates under field conditions. VL - 11 IS - 2 ER -
Department of Cellular, Microbial and Molecular Biology, Addis Ababa, Ethiopia
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