Water shortage is a big problem for growing wheat in North China. Scientists tested different amounts of water at different growth stages to see what works best. They found that giving more water didn't always mean more wheat. The best way was to keep the soil moist at sowing, jointing, and anthesis stages. This helped the wheat grow well and use water efficiently. By using this method, they got the highest yield and water use efficiency. They also found that you can estimate deep soil water by looking at shallow soil moisture, making it easier to know when to water the wheat.