In order to clarify the effects of aeration on root nitrogen metabolism in rice seedlings,rice cultivars Guodao 6 (indica) and Xiushui 09 (japonica) were investigated for root growth,the activities of glutamine synthetase (GS),glutamic acid-pyruvic acid transaminase (GPT) and glutamic acid oxaloacetate transaminase (GOT),the nitrate (NO 3-N) concertration,the contents of free amino acids and soluble sugar in root under hydroponics with continuous aeration treatment.The results showed that rice seedlings grown in oxygenation solutions had higher root dry matter,longer root length,stronger root activity and larger root absorption area compared with the control.In addition,the contents of soluble sugar,root vigor and the activities of GS,GOT and GPT in the aeration solutions were higher than those in the control.The results also indicated that the activities of enzymes involved in root nitrogen metabolism of Xiushui 09 were enhanced by aeration,however,there was no significant influence on root nitrogen metabolism of Guodao 6,which suggested that effect of oxygenation on rice root nitrogen metabolism might be genotype-specific. In order to clarify the effects of aeration on root nitrogen metabolism in rice seedlings, rice cultivars Guodao 6 (indica) and Xiushui 09 (japonica) were investigated for root growth, the activities of glutamine synthetase (GS), glutamic acid-pyruvic acid transaminase (GPT) and glutamic acid oxaloacetate transaminase (GOT), the nitrate (NO 3-N) concertration, the contents of free amino acids and soluble sugar in root under hydroponics with continuous aeration treatment. The results showed that rice seedlings grown in oxygenation solutions had higher root dry matter, longer root length, stronger root activity and larger root absorption area compared with the control. addition, the contents of soluble sugar, root vigor and the activities of GS, GOT and GPT in the aeration solutions were higher than those in the control. results that indicated that the activities of enzymes involved in root nitrogen metabolism of Xiushui 09 were enhanced by aeration, however, there was no significant influence o n root nitrogen metabolism of Guodao 6, which suggested that effect of oxygenation on rice root nitrogen metabolism might be genotype-specific.