Objective To investigate the differences in the composition and spatial structure of bud bank of Nitraria tangutorum seedling under the different nitrogen addition gradients, and nutrient limitation and nitrogen utilization, and to reveal the linkage between the quality of roots and cuttings and the bud bank, and finally elucidate the adaptation strategies of bud bank for the nitrogen availability.

Method The bud bank traits of N. tangutorum seedlings under different nitrogen addition were studied using pot experiments. The N addition levels consist of 0, 12, 24, 36, 48 and 60 mmol·L^-1.

Result The nitrogen addition significantly increased the number of buds and vegetative shoots in bud bank, and significantly reduced the number of dormant buds and dormant shoots; meanwhile, the nitrogen addition promoted the bud production of secondary shoots and tertiary shoots. With the increasing of nitrogen addition, the relative position of vegetative shoots in bud bank had a tendency to move from base to tip. There was a quadratic nonlinear positive correlation between nitrogen balance index (NBI) and budding intensity, branching intensity, bud production of secondary and tertiary shoots of N. tangutorum seedling; The N content, accumulation amount (NAA) and the morphological traits underground were positively related to the number of buds and vegetative shoots, and negatively related to the number of dormant buds and dormant shoots.

Conclusion Among the six nitrogen addition gradients, most of the indicators reached their maximum values in either 36 mmol·L^-1 or 48 mmol·L^-1 N addition levels, which were the optimum N additions for N. tangutorum seedlings. Nitrogen addition has a significantly influence on the bud bank size and spatial distribution of N. tangutorum seedlings, which also reflects a response to the changing nutrient availability.