Rice Genomics and Genetics 2025, Vol.16, No.2, 61-70 http://cropscipublisher.com/index.php/rgg 64 4.2 Stress tolerance Water and nutrient synergy plays a vital role in enhancing rice's stress tolerance. The integration of water-saving irrigation techniques with nutrient management, such as the 30% water-saving irrigation combined with conditioners, improves rice's resilience during critical growth stages like tillering and grain filling (Lu and Li, 2023). This approach not only supports better growth under water-limited conditions but also enhances nutrient absorption, contributing to improved stress tolerance. Moreover, the use of optimized nitrogen management strategies, such as the N4 treatment, reduces ammonia volatilization and supports delayed senescence, which helps maintain higher leaf SPAD values and canopy photoassimilation, thereby enhancing stress tolerance (Ma et al., 2023). 4.3 Yield components The synergistic management of water and nutrients significantly impacts the yield components of rice. For instance, the W1F3 treatment has been identified as optimal for increasing nitrogen uptake and improving the harvest index, leading to higher yields (Zhu et al., 2024a). Similarly, the use of controlled-release fertilizers combined with urea (CRBF+U) has been shown to improve the grain number per panicle, seed-setting rate, and actual yield by enhancing nitrogen use efficiency and reducing nitrogen losses (Wu et al., 2023). Additionally, integrated nutrient management strategies, such as combining organic and inorganic sources with biofertilizers, have been found to enhance yield attributes like panicle length and grain weight, ultimately boosting productivity and profitability (Table 1) (Kumar et al., 2023). 5 Environmental Implications of Water and Fertilizer Management 5.1 Water use efficiency and conservation Water management strategies such as alternate wetting and drying (AWD) and optimized irrigation schedules have been shown to significantly improve water use efficiency in rice cultivation. For instance, AWD can save 40%~44% of water compared to continuous flooding, while maintaining similar grain yields (Santiago‐Arenas et al., 2021). Additionally, the use of water-saving irrigation methods like “thin, shallow, wet, dry irrigation” can reduce irrigation water by 35.2% and increase water productivity by 42.0%~42.8% (Zhu et al., 2024a). These strategies not only conserve water but also enhance the sustainability of rice production systems. Through comparative experiments, we found that before rice seedlings reached a height of 5 cm, drone direct seeding required two fewer irrigation cycles and reduced water usage by 50% compared to mechanized transplanting, while the rice yield remained nearly the same. 5.2 Nutrient use efficiency and pollution reduction Optimizing nitrogen (N) management is crucial for improving nutrient use efficiency and reducing environmental pollution. Precision nutrient management techniques, such as the use of Nutrient Expert® and SPAD meter-based N management, have been shown to save up to 27.1% of nitrogen while increasing grain yields and water productivity (Pratap et al., 2022). Moreover, reducing nitrogen application rates from 120 to 60 kg/ha can achieve desirable grain yields and water productivity, significantly lowering fertilizer input costs and environmental impact (Santiago‐Arenas et al., 2021). These practices help in minimizing nitrogen losses and reducing greenhouse gas emissions, such as nitrous oxide (N2O) (Sadhukhan et al., 2023). 5.3 Ecosystem services Water and fertilizer management also play a role in enhancing ecosystem services. The integration of organic fertilizers with conventional NPK fertilizers can improve soil health by enhancing the soil fungal community, which in turn supports higher rice yields (Guo et al., 2022). Additionally, improved water management practices can reduce methane (CH4) emissions by 30%~34% and nitrous oxide emissions by 64%~66%, contributing to a lower greenhouse gas footprint (Islam et al., 2020). These practices not only support sustainable rice production but also contribute to broader environmental benefits by maintaining ecosystem balance and reducing pollution.
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