Abstract: In this study, GUS gene was transfered into the donor strain S.fredii 8855 using GUS (β-glucuronidase) gene marking technique . Nodules occupied by the marked strain turned blue in the GUSstaining buff, while others occupied by the indigenous rhizobia didn't. The effects of indigenous rhizobia on inoculation could be valuated by the technique easily. Greenhouse experiments showed that the ability of acid and alkaline resistance of S.fredii 8855 was higher than that of the indigenous rhizobia, and it could migrate in large scale in the soil. Inoculation significantly increased the yield of soybean when the nodule occupancy was no less than 43%. The yield was positively related to the nodule occupancy (r=0.98), but unrelated to the total nodule number (r=0.13). Nodulation was inhibited by soil Nand promoted by Papplication.

Key words: GUS gene marking, Nodulation, Nodulating competitiveness, travel cost interval analysis, recreational value, willingness-to-pay, travel cost model, zonal travel cost model, Beijing Olympic Forest Park