Increasing nitrogen (N) acquisition of plants is a way to enhance N fertilizer use efficiency. The capacity of a plant taking up nitrate is a function of the activity of its N transport system and the size and architecture of its root system. In the present study, two maize (Zea mays L.) inbred lines, 478 (N-efficient) and Wu312 (N-inefficient), were selected to determine the relative importance of N uptake system and root growth in N acquiring ability. Their differences in N assimilation characters were in...