High Efficient Use of Limited Supplement Water by Dryland Spring Wheat

Considering water limited conditions in the semiarid areas of the Loess Plateau, dryland spring wheat was chosen as the research materials, high efficient use of limited irrigation was studied. Under the three levels of fertilizer input and the jointing, heading, grain filling stages of limited water supplement conditions, plant growth, grain yield components and water use efficiency were measured. The results showed that leaf area, root system, and grain yields were promoted significantly by soil fertilization. Under the soil fertilized conditions, limited water supplying at the jointing stage was able to enhance kernel number per ear and kernel mass obviously. The maximum supplementary irrigation water to meet the greatest grain yield of spring wheat was about 200 mm. The suitable supplementary irrigation water to satisfy the highest crop water use efficiency was 100 mm. The limited supplementary irrigation water to meet the optimal irrigated water use efficiency is 60 mm. In the case of 60 mm supplementary irrigation, crop water consumption, water use efficiency and irrigation efficiency were greatly improved synchronously. And also, efficiency of stored soil water used by crop was increased correspondingly. It is concluded that critical quantum of limited irrigation water for dryland spring wheat was not less than 60 mm in the Loess Plateau. Effects of limited irrigation indicated that the best period of limited water supply should be the jointing stage.