Abstract: 【Objective】In view of the law of nitrogen uptake and accumulation of maize in seed production in China is unclear, the responses of biomass accumulation, yield formation, and the nitrogen uptake to nitrogen supply were studied in order to provide theoretical basis for green and efficient hybrid maize seed production. 【Method】Taking the parent variety combination of large area seed production as the experimental material, the on-site experiment was carried out from 2019 to 2020. A completely random block design was applied to study the effects of different nitrogen gradients on parental biomass, grain yield and nitrogen uptake and accumulation of maize seed production. Four nitrogen gradients were set up as basal fertilizer control (CK), 168, 240 and 320 kg N·hm^-2, respectively. 【Result】The accumulation of parental biomass of hybrid maize seed production increased with the increase of nitrogen gradients. The yield of maize seed production increased at first and then remained stable with the increase of nitrogen gradients. N240 treatment achieved higher yield, nitrogen use efficiency and grain nitrogen concentration at the same time, which were consistent in the two years. The yield of N168 treatment was higher than that of N240 treatment in the second year, but the nitrogen concentration was lower than that of N240 treatment. The nitrogen concentration of the whole plant of female parent straw and male parent was higher in high nitrogen gradient treatment than that in low nitrogen gradient treatment; the critical nitrogen concentration of maximum biomass of female parent at filling stage was 15.08 g·kg^-1, and there was a linear correlation between female parent biomass and nitrogen concentration at harvest stage. The post-silking biomass of each topdressing nitrogen fertilizer treatment was higher than that of pre-silking stages in two years, and increased with the increase of nitrogen gradients. The change rule of post-silking nitrogen uptake ratio with nitrogen gradients was consistent with the biomass. There was no significant difference in yield level, biomass accumulation, and nitrogen uptake between N320 treatment and N240 treatment. Under the premise of comprehensive consideration of yield and hybrid seed quality, N240 could be regarded as the recommended nitrogen application rate for hybrid maize seed production in this region. 【Conclusion】The optimal nitrogen application rate can increase yield and nitrogen use efficiency by regulating the ratio of nitrogen uptake for maize parents in pre- and post-silking in seed maize production. This study revealed that optimizing nitrogen application rate to stabilize nitrogen uptake in the pre-silking stage and ensure nitrogen supply after anthesis was the key to achieve high yield and nitrogen use efficiency of seed maize, and provided a theoretical basis for sustainable production of hybrid seed maize.

Key words: hybrid seed maize, yield, biomass, critical nitrogen concentration, nitrogen uptake