Biological nitrogen fixation, mycorrhizal infection and Azolla symbiosis in two rice cultivars in Egypt

In this study, the effect of biofertilizers i.e. Azolla pinnata, arbuscular mycorrhizal fungi [AMF] and Azospirillum brasilense [Az] on the growth, grain yield, biological nitrogen fixation [BNF] and nutrient uptake by rice cultivars [Oryza sativa var. Giza 172, IR 28] was examined. The grains produced from the inoculated treatments were more than that from the uninoculated control. Similar trends were observed with N, P and K uptake by both rice cultivars. The inoculation treatments reflected that Azolla and its combinations had less N derived from fertilizer [Ndff] and higher N derived from air [Ndfa], while Azospirillum or AMF had higher Ndff and less Ndfa. 15N recovery percentages confirmed that AMF was the most effective inoculum for enhancing soil and/or fertilizer N uptake by rice cultivars, while Azolla was considered a suitable agent for transferring fixed N to rice plants

Biological N2-fixation and growth of soybeans as affected by inoculation and residual 15N

The effect of inoculation with Bradyrhizobium japonicum either solely or in combination with Azotobacter chroococcum was examined for the growth and N2 fixation of soybean plantsSoybeans were fertilized with 15N-urea or ammonium sulfate and the isotope dilution technique was used for the quantification of N2 fixationDry mass and N uptake by inoculated plants were higher than those of the uninoculated plants Inoculation with sole or mixed inoculants induced 80-90% of dry matter and N yields of the plants fertilized with the full dose of N [40 mg N kg-1 soil]Those two parameters were higher in case of urea fertilization as compared with ammonium sulfate Similar trend was observed between the two seasons, where the dry mass and N uptake were higher with the first soybean crop comparable with the succeed soybean crop Generally, the nodulated soybean produced higher dry matter yield and accumulated more nitrogen than the non-nodulated isoline Nitrogen derived from air [Ndfa%] was ranged from 42 to 65% depending on the inoculation treatments Fixed N2 is the most important source of N utilized by the undulating soybean, while the non-nodulating isoline uptakes more nitrogen from soil and fertilizer

Yield and N2-fixation of groudnut [arachis hypogaea L.] in response to inoculation with selected bradyrhizobium strains and mycorrhizal fungi

The effect of inoculation with Bradyrhizobium and/or arbuscular mycorrhizal fungi in the presence of super or rock-P on yield and nutrient content was studied in a pot experimentInoculation with Bradyrhizobium [strain 3456] increased undulation and nitrogen content superior to strain 3339, either super or rock-P, was added and at the same time these parameters were higher in case of rock-P than superphosphate application Inoculation with a mixture of the three inoculants decreased the amount of fixed nitrogen comparable to any other inoculation treatmentsThe possibilities of saving more than 50% of the recommended N fertilizer may be achieved Superphosphate could be replaced by rock-P either solely or in combination with arbuscular mycorrhizal fungi Based on 15N analysis, groundnut derived more nitrogen from air [Ndfa] than from fertilizer [Ndff] or soil [Ndfs]

Evaluation of Biological Nitrogen fixation by faba bean [vicia faba L.] plants using N-15 dilution techniques

A greenhouse experiment was carried out to evaluate BNF by faba bean using 15N dilution technique. Three cultivars of labs bean i.e. Giza 2, Giza 461 and Rentablanka were used as N-fixing crops, wheat [Sakha 69] was used as a reference crop. Uninoculated and inoculated seeds with Rhizobium and/or VAM were sown in sandy soil unattended with labeled 15NH4N03 [15 kg N/fed, 4.68% 15N a.e.] or 15N rice straw [0.2 o w/w, 1.63% 15N a.e.]. Rock-P was added as a source of P at rate of 20 kg P/fed. Generally, from the economical and environmental point of view, application of N2 fixers and vesicular arbuscular mycorrhizal fungi in combined inoculants for legumes can save about 80% of N and 50% of P fertilizers. The use of organic N source as slow release fertilizer in virgin uncultivated and unreclaimed soil in Egypt speeds up the biological activity of these soils