The morphology and spatial distribution of maize cultivars with high NUE are more optimized for having deeper growth, which was beneficial for uptaking water and nutrients from soil and delaying the aging process. The root dry weight of maize treated with N fertilizer is higher than the control regardless of water conditions. The increase of shoot biomass is even more evident in N treated plants. A lower root to shoot ratio causes a greater water loss through the leaf respiration and impairment in water balance in crops (Zhang and Shan, 1995). Increasing root density and length are considered as a low energy demanding strategy to obtain water and N under water stress by plants (Hofer, 1986).