Dual inoculation with strains of Bradyrhizobium japonicum and Azospirillum brasilense to improve growth and biological nitrogen fixation of soybean (Glycine max L.) |
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Authors: | Y G M Galal |
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Institution: | (1) Agricultural Department for Soil and Water Research, Nuclear Research Centre, Atomic Energy Authority, Abou Zaabl, 13759, Egypt Fax: (202) 354-0982, EG |
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Abstract: | The effects of inoculation with Bradyrhizobium japonicum and Azospirillum brasilense strains on the growth of soybean were evaluated with regard to the estimation of N2 fixation using the 15N isotope dilution technique. Inoculation, in general, increased the dry mass of soybean as well as nitrogen content. Dual
inoculation with a mixture of B. japonicum and A. brasilense strains was superior over single inoculation with B. japonicum. Nitrogen fixed (Ndfa) varied according to inoculant and soil conditions. Percentages of nitrogen derived from air (% Ndfa)
using a non-nodulating isoline were 72% and 76% for B. japonicum and B. japonicum plus A. brasilense, respectively, in non-sterile soil. A similar but higher trend was recorded in sterilized soil, in which the percentages
of N2 fixed were 81% and 86% for single and dual inoculation, respectively. The correlation coefficient between N2 fixed and N uptake (r=0.94) and dry mass (r=0.89) was significant. Application of special bacterial inoculants in agricultural systems of Egypt seems to be a promising
technology and could be used for improving soybean growth as well as soil fertility, thus minimizing environmental pollution.
Received: 10 January 1996 |
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Keywords: | Soybean Isotope dilution Nitrogen fixation Bradyrhizobium japonicum Soil sterilization 15N Azospirillum brasilense Bacterial inoculation |
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