Abstract:A field trial of limited irrigation on dryland spring wheat in a semi-arid region of China showed that: irrigating at the seedling stage reduced the total root weight and root density from the 3-leaf stage to heading stage of spring wheat markedly; it promoted the root growth at the flowering stage; and increased the water use efficiency and grain yield of spring wheat. However, water stress at the seedling stage resulted in the root system becoming too large during the early growth period and thus influencing shoot growth and aggravating the deficit of soil water, thereby ultimately seriously reducing the grain yield.