In this dissertation,shuangfeng8of sugar beet was seleeted as experimental sample,andexperiments were made in NEAU.Experimental factors were as follows: NO3-、NO_2~--、NH_4~+,pH.In experiments the quadratic rotation-orthogonal combination1/2design wasadopted.We comprehensively and systematieally stodied on dynamic changes andregulation approaches of key enzymes of inorganic nitrogen assimilation metabolism,photosynthetic rate (Pn) and main products. Nitrate reductase (NR) and nitrite reductase(NiR) coupling r...