Abstract:Nitrogen utilization efficiency of 20 rice varieties was studied under 3 Nitrogen application lev-el(25kg,125kg,225kg per ha).The results showed Nitrogen utilization of tested varieties was divided into four kinds: efficient,inefficient,efficient at low and medium Nitrogen level,and efficient at high Nitrogen level.Ni-trogen utilization of ‘Ji 03-2355’, ‘Ji 03-2843’, ‘Ji 06-56’ and ‘Jisheng 286’ were efficient,whereas that of ‘Ji 06-39’, ‘Ji 06-44’ and ‘Ji 03-55’ were inefficient.Nitrogen utilization of ‘Jijing 66’, ‘Ji 06-55’ and ‘Jijing 81’ were efficient at low and middle Nitrogen level,while that of ‘Jijing88’ and ‘Ji 06-43’ were efficient at high Ni-trogen level.Rice varieties which Nitrogen utilization was efficient had high yield and high dried bio-mass yield no matter in low,medium and high Nitrogen area.On the contrary,rice varieties which Nitrogen utilization was inefficient had low yield and low dried bio-mass yield in all treatments.Rice varieties which Nitrogen utiliza-tion was efficient at low and medium Nitrogen level means they have high yield and high dried bio-mass yield in that condition.Rice varieties which Nitrogen utilization was efficient at high Nitrogen level means they have high yield and high dried bio-mass yield in that condition.