Abstract: This study showed that inoculation of endophytic Paenibacillus polym yxa S-7 could significantly (P<005) promote the photosynthesis of sugar beet. After the inoculation, the leaf net photosynthetic rate (Pn), stoma tal limitation (Ls), stomatal conductance (Gs), and transpiration r ate (Tr) increased by 1611%, 2382%, 4191%, and 3480%, respectively , while the stomatal intercellular CO2 concentration (Ci) decreased by 2 1. 09%. Inoculation of endophytic P. polymyxa S-7 could also increase sugar be et yield and its quality significantly (P<005), with the tuberous root bio mass and its sugar content increased by 2563% and 1746%, respectively. It wa s concluded that endophytic P. polymyxa S-7 not only affected the photosynt hetic parameters, but also promoted the yield and quality of sugar beet.

Key words: dairy farm, nitrogen surplus, nitrogen use efficiency, stocking density, nitrogen management.