Document Type : Research Paper
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Abstract
Nitrogen is one of the most important macro nutrients in plants which its shortage in soil is the main factor limiting plant growth. Nitrogen molecular gas comprises about 80 % of the atmospheric gases whereas it is not directly absorbable in plants. A symbiosis of legumes and rhizobia is one of the most important ways in nitrogen fixation. Fertilizer application in rangelands especially in arid and semi arid regions which always faces limiting moisture will result in small efficiency of the fertilizer and also imposes heavy costs due to environmental pollution (soil and water). Native Trifolium species are of utmost nitrogen fixers in Khuzestan rangelands. This experiment was carried out in 3 years to isolate, identify and introduce rhizobium strain of the native Trifolium species in Khuzestan. A total number of 70 samples were collected from 12 Trifolium species and after root washing and separation of root nodules in laboratory, the rhizobium bacteria were planted and isolated on YMA. Finally, 9 strains of Rhizobium trifolli were identified based on morphological characteristics and growth rate.
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