Understanding crop physiology provides us with an exciting information and knowledge for better crop management towards increasing productivity. Based on this fact, many physiological aspects of cereal crops (wheat, rice, sorghum and barley) have been studied during the last two decades in Iraq with interesting achievements. These aspects included : physiological aspects of tillering in wheat and its relationship to the crop management and grain yield ,seed priming of rice and sorghum for better seed germination and field establishment, accurate timing of agrochemicals application (e.g. nitrogen fertilizer and plant growth regulators) based on certain critical growth stages to increase grain yield of wheat and barley, and proposed strategies for saving water in rice cultivation among them growing rice successfully, under sprinkler irrigation for saving water and increasing water use efficiency (WUE). The objective of these four case studies was to improve the cereals management and, hence, increasing their grain yield via physiological approaches. Considerable increases in the grain yield of these cereals crops have been achieved via the combination of crop physiology and crop management. Full details of the methodologies and achievements will be presented for each case study. In conclusion, this approach, may represents a good and effective strategy to increase crop productivity and saving water.