Phenotypic and Symbiotic Characteristics of Rhizobia Nodulating Field Pea (Pisum Sativum L.) in Southern Tigray, Ethiopia.
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Date
2010-06
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Addis Ababa University
Abstract
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
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Keywords
Field pea, Tigray, phenotypic characters, symbiotic effectiveness, Rhizobium