Studies On Adaptability Of Rhizobium To Soybean And Soil

Symbiotic nitrogen fixation action of Rhizobium and leguminous plant is the most effectivenitrogen fixation system with the highest amont nitrogen fixed in nature. The main influence factorsfor nodulation and nitrogen fixation of Rhizobium include soil, Rhizobium and leguminous plant.Rhizobia suitable for different soybean varieties and different soil types from main production areaof soybean in Heilongjiang province were searched to screen the best combination of Rhizobiumwith soybean and siol, at the same time, providing the theory basis of screening the excellentnitragin.The Rhizobium were directly isolated from soybean nodule. The initial screening was basedon plant height, dry weight of plant, number of nodules, dry weight of nofules and some otherindexes.The results showed that the best variety was V₁, followed by V₂, the optimum strains wereR₁,R₅ and R₈. The varieties and strains were used in the following pot experiment.The strains R₁, R₅, R₈ and the control R_ck were inoculated on the varieties V₁ and V₂ byspheroidizing treatment, then the inoculated seeds were separately sown in the black soil andmeadow soil. In the period of flourish flowers nitrogenase activity, ureide, symbiotic nitrogenfixation efficiency were determined. The quantity and qulity of soybran were determined during theharvest. Based on variance analysis and significance comparison, the following conclusions weredrown: black siol responded better to the inoculum than meadow soil; the yield of V₂ was highersignificantly than that of V₁ , but symbiotic validity of inoculated Rhizobium and V₁ was muchhigher; both V₁ and V₂ had a broad-spectrum inoculum, and better compatibility, which was provedby the easier infection nodulation by most of rhizobia. R₁ had strongest infecting ability, highestcapability of symbiotic nitrogen fixation and best matching with host. Moreover, R₁ representedbetter matching with V₁ and stronger adaptability to S₂. It also showed better performance innitrogenase activity, ureide content, dry weight of nodules, yield and some other indexes. The bestmatchs of rhizobia, two varieties and two types of soil were: R₁V₁S₁,R₁V₂S₁,R₁V₁S₂,R₁V₂S₂.Rhizobia, legumes and soil have influence on nodulation and nitrogen fixation. And soil typewas the primary factor affecting nodulation and nitrogen-fixation, the next was inoculum. Incrossing action, the match of soybean variety and rhizobia was the main factor that affectedsymbiotic nitrogen-fixation. So in order to get optimum inoculating effect, it is necessary to theoptimum match of Rhizobium and soybean in certain soil.Nitrogenase activity has certain influence on the yield of soybean and total amount of the protein and the fat of soybean seeds; the correlation of nitrogenase activity,dry weight of nodulesand ureide content was extremely remarkable; the correlation of the symbiotic nitrogen-fixingefficiency and the yield of soybean was extremely remarkable.Planting soybean may increase soil fertility. The organic matter in the black and meadow soilwere 13.42% and 10.95% higher after harvest separately than that before sowing, the alkalidispelled nitrogen were 27.47% and 17.4% higher separately. The PH also increased, other indexeshad no significant change.