Abstract: The effects of 7.5 and 15.0 t biochar per hectare on nitrogen use efficiency of two kinds of panicle type japonica rice （Oryza sativa L. subsp. japonica） were studied by using Beijing 1 and Tiejing 11 as experimental materials. The results showed that the application of 7.5 t/hm² biochar had no significant effect on the nitrogen content and nitrogen uptake of leaves, stems and panicles of Beijing 1 and Tiejing 11 at the maturity stage compared with conventional fertilization. When the application rate increased to 15.0 t/hm², the nitrogen uptake of leaves of Beijing 1 and the nitrogen uptake of panicles of Tiejing 11 increased, resulting in a significant increase of 4.2% and 6.8% in total nitrogen uptake of plants, respectively. When 7.5 t/hm² biochar was applied, the nitrogen harvest index and nitrogen physiological utilization rate of Beijing 1 did not change significantly, but the nitrogen recovery rate, nitrogen agronomic utilization rate and nitrogen partial factor productivity increased significantly by 8.1%, 18.0% and 6.5%, respectively, while only the nitrogen recovery rate of Tiejing 11 increased significantly by 9.6%. When applied to 15.0 t/hm², the nitrogen recovery rate, nitrogen physiological utilization rate, nitrogen agronomic utilization rate and nitrogen partial factor productivity of Beijing 1 increased by 9.0%, 20.7%, 31.1% and 11.2%, respectively. The nitrogen recovery rate, nitrogen agronomic utilization rate and nitrogen partial factor productivity of Tiejing 11 increased by 13.3%, 20.1% and 7.4%, respectively, there was no significant change in the nitrogen physiological utilization rate. The application of biochar can improve the nitrogen use efficiency of japonica rice. The semi-erect panicle variety Tiejing 11 needs to apply more biochar than the erect panicle variety Beijing 1 to achieve a comprehensive optimization of the nitrogen absorption and utilization system.

Key words: biochar, panicle type, Japonica rice（Oryza sativa L. subsp. japonica）, nitrogen use efficiency