الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The common bean (soybean and faba bean) is an important food crop in the tropics and subtropics, supplying about 20% of the protein intake per person. Of the 102 Mt of the grain produced in the world in 1977, the African region contributed 7 Mt of which 60% was produced by the Eastern African Countries. Fertilizers are costely and often not avialbe to the small farmer, so alternatives for overcoming nutrient constraints in beans need to be investigated. one alternative is to improve the nitrogen -fixing symbiosis of soybean and faba bean with the bacterium Bradyrhizobium japonicum and Rhizobium ieguminosarum biovar Viciae. Genetic diversity for both components of the symbiosis has been demos traded and offers potential for improvement. The improvement of nitrogen fixation in these legumes may lead to increased yield and reduced fertilizer requirement. Dinitrogen fixation is important for the growth and production of soybeans, faba beans and other legumes, especially in soils containing low nitrogen. Soybeans and faba beans nodulated by B. japanicum and R ieguminosarum biovar Viciae strains, respectively can derive nitrogen from either the symbiosis or the soil. Previous studies
• indicated that under high soil nitrogen about 20% of the plant nitrogen was fixed symbiotically, but if the soil nitrogen was low, the amount increased to 66% ?lld the symbiosis contributed up to 40% of total nitrogen under normal nitrogen levels. On the other hand, the ability to estimate accurately the amount of atmospheric nitrogen fixed by the bacteria is prerequisite to attempting genetic improvement or”the nitrogen -fixing symbiosis for increased nitrogen fixation. Herin results will be useful in devising applied strategies for improved nitrogen fixation symbiosis of the host plant with the bacterium. The objectives of this study were attempt to throw some light on the genetic behaviour of nodulation.