Phenotypic and Symbiotic Characteristics of Rhizobia Nodulating Field Pea (Pisum Sativum L.) in Southern Tigray, Ethiopia

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Addis Ababa University


Nitrogen is one of the most abundant elements, and BNF is the main source of nitrogen for Legumes plants. Field Pea is one of the most important Legumes plants and widely grown in Tigray regional state. Although some studies have covered some areas of Tigray in relation to biological nitrogen fixation, there was no comprehensive study on the crop in the most important pulse growing regions of Southern Tigray. The present study, therefore, was designed with the objective of isolating and characterizing root nodule bacteria from three Woredas of southern Tigray, and evaluating their symbiotic effectiveness on field pea. The result will serve as base line data for future endeavor of utilizing biological nitrogen fixing system of field pea to increase productivity into low-input agriculture of the region and the country at large. Thirty three soil samples were collected from field pea (Pisum sativum) growing areas of Southern Tigray (Ofla,Endamokoni and North western parts of Alamata Woreda) . The soil samples were brought to Applied Microbiology Laboratory for further processing. For induction process the soil samples mixed with the extensively washed and sterilized river sand and filled in to surface sterilized 3kg capacity plastic pots. Seed of the cultivar Pisum sativum Addi surface sterilized and sown into each pot and placed in the greenhouse condition .After 55 days plants were uprooted and collected nodules of all isolates were induced into the original host plants. All isolates characterized their morphological and physiological characteristics. All isolates formed watery and mucoid colonies on YEMA medium, their mean growth time mostly between 2 &4 hours and failed to grow on peptone glucose agar medium and to solubilize inorganic phosphate. Almost all isolates were tolerate to pH 5to 9, salt concentration, and at temperature of 15oc to 35oc. The isolates were also tolerant to ampicillin, penicillin, erythromycin and chloramphenicol, but sensitive to gentamycin and tetracycline. All isolates utilized to sucrose, glucose and D-manitol but few isolates utilized citrate, cellulose and starch, and the isolates utilized many amino acids as the source of nitrogen. The numerical analysis based on the 54 phenotypic characteristics of isolates was clustered into six groups. The mean nodule number, nodule dry weight and mean shoot dry weight of the host plants inoculated with different isolates showed variations. After in field experiments, the isolates (AAUFPR05, 06, 07,11,16,18 and 30, 37, 39 and 43), and particularly AAUFPR 07and 28 can be recommended as inoculants in the future. The above isolates showed good physiological,eco-physiological and symbiotic characteristics. Key Words: Field pea, Tigray, phenotypic characters, symbiotic effectiveness, Rhizobium



Field Pea, Tigray, Phenotypic Characters, Symbiotic Effectiveness, Rhizobium