Maize Genomics and Genetics 2025, Vol.16, No.5, 267-275 http://cropscipublisher.com/index.php/mgg 270 Figure 1 Schematic diagram of artificial warming shed; high temperature (A); high temperature+supplemental irrigation (B) (Adopted from Jian et al., 2024) 5.2 Changes in soluble sugar and protein content Irrigation can also affect the nutritional quality of corn, such as sugar and protein in the kernels. Studies have found that when the water volume is controlled at around 70%, the sugar and protein content of sweet corn is the highest. If there is less water, not only will the yield decrease, but the quality will also deteriorate (Ertek and Kara, 2013). Proper watering during the filling period can increase the starch and soluble sugar in the stems and leaves. These substances will flow to the kernels, help filling, and make the corn taste better and more nutritious, especially when encountering high temperatures (Jian et al., 2024). Therefore, a reasonable arrangement of water volume can not only increase yield, but also improve the nutritional value and processing quality of corn. 5.3 Influence of irrigation rhythm on quality stability The rhythm and frequency of irrigation will also affect whether the quality of the kernels is stable. If irrigation can be done on time and as needed, such as using interval drip irrigation or adjusting the irrigation system, the corn filling process can be more uniform, the grain weight can be more consistent, and it will not be easily affected by weather changes (Wang et al., 2020; 2021; Cao et al., 2022; Ocwa et al., 2024). In addition, optimizing irrigation methods and planting methods together can further maintain seed quality, such as reducing unfilled grains and reducing germination failure rates, so that the yield and water use efficiency of the entire field can be improved. These studies show that irrigation must be coordinated with the growth rhythm of corn, especially during the critical growth stage, so as to ensure high yields and stable grain quality. 6 Case Studies: Regional Irrigation Management Practices 6.1 Water-saving irrigation in the semi-arid North China Plain Water resources in the North China Plain are tight, and the groundwater level has been declining. In order to ensure that corn can continue to have high yields, water-saving irrigation has been promoted locally. Long-term studies have found that in the rotation of winter wheat and summer corn, if the amount of wheat irrigation is appropriately reduced, although the wheat yield will decrease slightly, the corn yield can be maintained or even increased, and the overall water use is more efficient. For example, there is a practice called "minimum irrigation (MI)", which controls the soil moisture within a suitable range during sowing and no longer irrigates in the later stage. In this way, corn can save half of the water used in a year, the water use efficiency can be increased by 10%, and the yield is only about 13% less than that of full irrigation. In addition, there is another way to irrigate wheat twice and corn only once (W2M1), which is more effective than the traditional method of irrigation with more water and large investment. Not only does it stabilize grain production, but it can also slow down the decline of groundwater (Wang et al., 2018; Yang et al., 2022; 2024). On this basis, if mulching, deep plowing, and returning straw to the field are used in combination, the water utilization rate can be further improved (Zheng et al., 2020).
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