Abstract: In order to investigate the effects of sulfur on the growth，the nitrogen and sulfur
assimilation of Chinese spring onion，the plant growth，nitrogen and sulfur content and activity of key
enzyme（NR，GS，ATPS，OASS）for assimilation of nitrogen and sulfur in the different S levels were
studied with potted sandy culture. The results showed that the growth，the N and S content，the yield and
quality were improved by appropriately increasing the content of sulfur，while the yield and quality were
reduced when the content of S level was over 4.01 mmol · L^-1. The activity of ATP sulfurylase（ATPS）of
leaves reduced with the S level increasing，while the activities of O-acetylserine thiollyase（OASS），nitrate
reductase（NR）and glutamine synthetase（GS）responded differently at each growth stage. In the initial
stage，the activity of NR was improved on the higher S level which had no significant effect on the
activities of GS and OASS. In the later stage，the activities of OASS and GS were enhanced on the appropriate S level，and the activity of NR was reduced. Comprehensive analysis of results showed that，
the nutrient solution containing 2.01 mmol · L^-1 was the optimal to improving the yield and quality of
Chinese spring onion，and the yield was 19.1% higher than the control（0.01 mmol · L^-1）.

Key words: Chinese spring onion, sulfur, yield, quality, nitrogen and sulfur assimilation