Maize Genomics and Genetics 2025, Vol.16, No.5, 267-275 http://cropscipublisher.com/index.php/mgg 269 irrigation appropriately will not have much impact, and can save water while maintaining yield (Comas et al., 2019). In addition, if irrigation and nitrogen fertilization are done well, more dry matter will flow to the grains, so that corn will not only produce more, but also use more water. On the contrary, if there is too little water, plant growth will slow down, and aboveground dry matter and total biomass will decrease. The extent of the impact depends on when the drought occurs and how long it lasts. 4 Optimization of Irrigation Modes and Timing 4.1 Comparison of drip, sprinkler, and furrow irrigation In corn cultivation, drip irrigation or underground drip irrigation is usually more effective than traditional furrow irrigation. These methods can not only increase yields, but also increase leaf area index (LAI) and water and nitrogen use efficiency (Sandhu et al., 2019; Wu et al., 2019; Li et al., 2021). For example, center pivot irrigation and underground drip irrigation systems generally have yields that are 8% to 25% higher than furrow irrigation. After drip irrigation, the leaf area index of corn can be increased by an average of 24% (Irmak et al., 2022). Compared with furrow irrigation and sprinkler irrigation, drip irrigation, especially when used in conjunction with mulching, has higher water use efficiency and economic benefits (Wang et al., 2020). In addition, drip irrigation can reduce the time and cost of field management and is more environmentally friendly, so it is quite attractive to farmers who engage in sustainable cultivation (Patra et al., 2023). 4.2 Effects of irrigation frequency on physiological traits When using drip irrigation, increasing the number of irrigations and fertilizations can make maize produce more and use water and fertilizer more reasonably. If irrigation is done with a small amount of water and more times, such as once every 7 days, the yield and water use efficiency of maize will be better than low-frequency or high-volume irrigation (Ma et al., 2022). This method can also allow maize to better absorb nitrogen fertilizer, improve photosynthesis efficiency, and have a more developed root system. Especially when used together with conservation tillage, the effect is more obvious (Li et al., 2023). To make these effects most obvious, the key is to match the supply of water and fertilizer with the needs of maize at different growth stages (Sandhu et al., 2019). 4.3 Precision irrigation and fertigation practices Precision irrigation technology and drip irrigation and fertilization technology can achieve "water and fertilizer follow the seedlings". This means that according to the different stages of maize growth, water and fertilizer are supplied on demand, not more or less, so that both yield and resource utilization can be increased. Compared with the old method, such as traditional furrow irrigation + fertilization, drip irrigation can increase corn yield by 12%, increase water use efficiency by 26%, and use nitrogen fertilizer more efficiently by 34% (Li et al., 2021). A better irrigation plan is to maintain a medium-high irrigation level, that is, 90% to 100% of the crop water requirement, and then combine it with staged fertilization. This will not only increase the yield, improve fertilizer absorption, and increase income, but also reduce nitrate loss, which is not good for the environment (Fan et al., 2020; Yan et al., 2021). Moreover, if managed properly, even if less fertilizer is used, it will not affect the yield, but will be more environmentally friendly and save more money. 5 Impact of Irrigation Regulation on Yield and Quality 5.1 Regulation of kernel number and thousand-kernel weight The time and amount of irrigation will directly affect the number of grains and thousand-grain weight of corn. Especially during the period from flowering to grain filling, if there is a lack of water, the number of grains per ear will decrease and the total yield will decrease significantly. This decrease is closely related to the duration and severity of water shortage (Mansouri-Far et al., 2010). If water can be supplemented during the grain filling period, it can not only reduce the pressure caused by high temperature and drought, but also allow corn to produce more grains, extend the grain filling time, make the grains fuller, and increase the thousand-grain weight. In drought weather, this can increase the yield by about 15% to 22% (Figure 1) (Wang et al., 2020; 2021; Jian et al., 2024). If a reasonable irrigation plan is arranged throughout the growing season and water is used in the critical period, not only can the number of grains increase, but the grain weight can also remain stable, and the final yield will be higher and more stable (Cao et al., 2022).
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