Plant Gene and Trait 2025, Vol.16, No.3, 133-141 http://genbreedpublisher.com/index.php/pgt 137 controlling nitrogen fertilizer between 125 and 200 kilograms per hectare leads to more commercial fruits, higher benefits, and can also improve the utilization rate of nitrogen fertilizer (Ronga et al., 2020; Shewangizaw et al., 2024). If combined with reasonable irrigation, the yield and water use efficiency can continue to increase (Li et al., 2020; Bello et al., 2024; Shewangizaw et al., 2024). 6.2 Fruit size, color uniformity, and shelf life If the fertilization method is well arranged, it can not only increase the yield but also make the tomatoes grow more beautifully. Appropriate and divided fertilization can make fruits larger in size and grow more evenly (Wang et al., 2021). When the supply of nitrogen is sufficient, tomatoes have brighter colors and can be stored for a longer time. At this time, the fruits have a high sugar content and a low acidity, and are more advantageous in transportation and preservation (Li et al., 2020; Wang et al., 2021; Luo et al., 2023; Bello et al., 2024). Moreover, if nitrogen fertilizer is used just right, tomatoes will have a stronger tolerance to high temperatures, and their appearance and quality can be better maintained (Luo et al., 2023). 6.3 Nutritional quality enhancements Applying nitrogen fertilizer in batches and in appropriate amounts can also enhance the nutritional value of tomatoes. Studies show that after scientific management of nitrogen fertilizer, the levels of vitamin C, sugar and lycopene in fruits will all increase (Li et al., 2020; Wang et al., 2021; Fan et al., 2022; Luo et al., 2023). If nitrogen fertilizer is appropriately reduced or less applied at certain stages, not only will the yield not decrease, but instead there will be more vitamin C and phenolic components in the fruits, making them more nutritious to eat (Hernández et al., 2020). In addition, when nitrogen fertilizer is applied appropriately, tomatoes can absorb more nutritional minerals such as protein, potassium and phosphorus, further improving the overall nutritional quality of the fruit (Ronga et al., 2020; Fan et al., 2023). 7 Interaction with Agronomic and Environmental Factors 7.1 Relationship with irrigation schedules The application of nitrogen in batches is closely related to the irrigation method and has a significant impact on both the fruit setting rate and yield of tomatoes. Under the planting methods of drip irrigation and furrow irrigation, using nitrogen fertilizer separately and multiple times can make tomatoes grow better and use less water. For example, in arid areas, if only half of the water is irrigated (such as using only 50% of the normal water volume), along with an appropriate amount of nitrogen fertilizer, not only can tomatoes grow well, have more fruits, and have better quality, but water can also be used more efficiently (Li et al., 2020; Fan et al., 2022; Bello et al., 2024). Under furrow irrigation conditions, if nitrogen fertilizer is divided into half for transplanting and half for the middle and late stages, the yield will be higher than applying it all at once (Wabela, 2018). In addition, adjusting the application time of nitrogen fertilizer and combining it with water-saving irrigation methods (such as phased water supply) can also ensure the yield while saving water (Ayankojo and Morgan, 2021). 7.2 Effects under organic and integrated nutrient management systems In organic farming or integrated nutrient management, applying nitrogen in stages also has obvious benefits. Research has found that during the seedling stage of tomatoes, less fertilizer is used. When they flower, they rely on the original nitrogen in the soil. It is not until the fruiting stage that more fertilizer is needed. If fertilizers are used reasonably according to each growth stage, not only can the yield be increased, but also the waste of fertilizers or nutrient imbalance can be avoided (Wang et al., 2025). In addition, some studies using foliar spraying of organic nitrogen (such as arginine) have also found that it can enable tomatoes to accumulate more nitrogen, enhance photosynthesis in leaves, and improve fruit quality (Wang et al., 2021). These results indicate that in organic farming, it is very important to apply fertilizers reasonably in stages. 7.3 Influence of soil type and climatic conditions Soil type and weather conditions can also affect the effect of phased nitrogen application. The effects of applying nitrogen in batches vary in different soils such as sandy soil and loam. Like in sandy soil, the fruit becomes larger more obviously in the later stage. But in loam soil, this effect is not very prominent. In different seasons, whether it is drought or humidity, the combination mode of water and fertilizer will also change, thereby affecting the yield
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