Many studies were conducted on plant nitrogen absorption, transformation, and physiology mechanisms improvement since 1980s (Bushoven and Hull, 2001). There were also many researches on physiological study of nitrogen metabolism with different water and nutrient contents. Physiological indicators, such as N content of enzyme activity, photosynthesis parameters, respiration parameters and osmoregulation substances, were used to test and evaluate the ability of plants to absorb and transform nitrogen. Nowadays, researchers focus on the function of nitrogen metabolism on enzyme regulation mechanism in plants (Dong, 2010). Nitrogen absorbed from plant roots was reduced to ammonia by nitrate reeducate (NR) and nitrite reeducate (NiR) in cytoplasm, continued to be reduced to glutamate and glutamine by glutamate synthase (GOGAT) and glutamine synthase (GS), then to aspartate (Asp) and asparagine (Asn), and finally to different amino acids and proteins for plant growth. The enzymes above were key enzymes for plant nitrogen metabolism, and their functions on physiological regulation function of N metabolism were investigated a lot (Yang et al., 2011).