Rice Genomics and Genetics 2025, Vol.16, No.1, 14-23 http://cropscipublisher.com/index.php/rgg 18 Integrated nutrient management in Yangzhou involves optimizing nitrogen application rates and timing to enhance yield and nitrogen use efficiency while minimizing environmental impacts (Guo et al., 2017). This approach has been shown to increase yield and partial factor productivity of nitrogen by adjusting application strategies, thus contributing to sustainable rice production. The integration of organic and inorganic fertilizers is also practiced to improve soil health and rice grain quality (Zahra et al., 2022). 4.1.2 Field management and nutrient application design Field management in Yangzhou involves the use of integrated crop management practices that combine increased plant density and optimized nutrient management to maximize grain yield (Wang et al., 2017). The design of nutrient application includes the use of both organic and inorganic fertilizers, with a focus on reducing nitrogen rates and improving application timing to enhance nutrient use efficiency and grain quality (Wang et al., 2019). This approach aims to achieve high yield and quality while reducing environmental impacts. 4.1.3 Data collection and quality evaluation methods Data collection in the field involves monitoring grain yield, nitrogen use efficiency, and grain quality parameters such as milling quality, appearance quality, and nutritional content (Gu et al., 2015; Can et al., 2021). Quality evaluation methods include assessing the milling quality (e.g., brown rice percentage, milled rice percentage), appearance quality (e.g., chalky kernels percentage), and nutritional quality (e.g., protein and micronutrient content) (Gu et al., 2015). These evaluations help in understanding the impact of integrated nutrient management on rice grain quality and guide further improvements in cultivation practices. 4.2 Case selection 2: major rice-producing area in Deqing County, Zhejiang Province Deqing County is located in the north of Zhejiang Province, in the hinterland of the Yangtze River Delta, with a subtropical monsoon climate. It has four distinct seasons, sufficient light, abundant rainfall, warm and humid. The territory is densely covered with water systems and fertile land, which is suitable for rice growth. Rice is the most widely planted grain crop in Deqing County. In 2024, the planting area of rice in the whole county reached 6000 hectare, dominated by high-quality rice varieties, such as' ningxiangjing 9 ',' zhehexiang 2 'and' zheyou 18 '. In recent years, the model of "rice duck co breeding" has been vigorously demonstrated and popularized, which has greatly improved the quality of rice (Figure 3). The "rice duck co breeding" model, which is dominated by ducks, forms an ecosystem with rice, insects, other microorganisms, field weeds, etc., uses duck manure as natural fertilizer instead of chemical fertilizer, makes full use of the omnivorous nature of ducks, feeds on rice flowers, weeds, pests, etc., and avoids the spraying of chemical insecticides, fungicides and herbicides, so as to produce high-quality green rice. Figure 3 "Rice duck co breeding" model in Deqing (Photographed by YuchaoShen) 5 Effects of Integrated Nutrient Management on Grain Quality 5.1 Appearance improvement under different treatments Integrated nutrient management (INM) has been shown to enhance the appearance of rice grains by improving plant growth parameters such as tiller number and panicle length, which contribute to a more uniform and appealing grain size and shape. For instance, the combination of inorganic fertilizers with organic sources like
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