Maize Genomics and Genetics 2025, Vol.16, No.1, 20-33 http://cropscipublisher.com/index.php/mgg 29 efficiency and yield stability (Al-Naggar et al., 2015; Zhang et al., 2021). Future research should continue to explore the genetic basis of these traits and develop new varieties that can thrive under high-density planting conditions while maintaining high nutrient use efficiency. This approach will be crucial for meeting the growing global demand for maize without expanding agricultural land. 9.3 Areas for further research to integrate planting and fertilization optimization While significant progress has been made in optimizing planting density and fertilization strategies, several areas require further research to fully integrate these practices. One critical area is the interaction between planting density, fertilization, and environmental factors such as soil type, water availability, and climate. Understanding these interactions can help develop more tailored and effective cultivation practices. For example, studies have shown that the optimal planting density and fertilization rates can vary significantly depending on local conditions, highlighting the need for site-specific recommendations (Piao et al., 2022; Zheng et al., 2023). Another area for further research is the long-term impact of optimized planting and fertilization practices on soil health and environmental sustainability. While increasing planting density and optimizing fertilization can improve yield and nutrient use efficiency, it is essential to ensure that these practices do not lead to soil degradation or increased greenhouse gas emissions. Research should focus on developing sustainable practices that balance high productivity with environmental conservation (Xu et al., 2017; Zhai et al., 2022). Additionally, exploring the potential of integrating organic fertilizers and cover crops into high-density planting systems could provide a more holistic approach to sustainable maize cultivation. 10 Concluding Remarks Optimizing planting density and fertilization strategies has a profound impact on achieving high-yield and sustainable maize production. The integration of increased planting density with reduced nitrogen (N) rates has been shown to enhance maize yield and resource use efficiency significantly. For instance, a study conducted in the Huanghuaihai Plain region of China demonstrated that a 30% increase in planting density combined with a 15% reduction in N rate improved maize grain yield by 6.6% and N partial factor productivity by 24.7%. Similarly, zigzag planting combined with deep nitrogen fertilization has been found to optimize root-canopy structures, thereby increasing maize yield and resource utilization. The balance between production efficiency and environmental responsibility is crucial. Excessive N fertilizer application not only leads to diminishing returns in yield but also poses severe environmental risks, such as increased greenhouse gas emissions and nutrient runoff. Research indicates that reducing N application rates while increasing planting density can maintain or even enhance grain yield and significantly improve N use efficiency, thereby reducing environmental impacts. For example, a study in the North China Plain showed that a higher planting density with a reduced N rate decreased N2O emissions and greenhouse gas intensity by 7.3% and 4.3%, respectively. Further research is essential to support the development of precision and sustainable agriculture. Future studies should focus on the long-term impacts of optimized planting density and fertilization on soil health, biodiversity, and overall ecosystem services. Additionally, the development of advanced agronomic practices and technologies, such as precision farming tools and decision support systems, will be critical in fine-tuning these strategies to local conditions and crop varieties. By continuing to explore and refine these approaches, we can ensure that maize production remains both highly productive and environmentally sustainable. Acknowledgments We would like to thank the two anonymous peer reviewers for their valuable comments and recommendations. Funding This work was supported by the Major Scientific and Technological Project for New Agricultural Varieties Breeding of Zhejiang (2021C02064-4-4), Regional Demonstration Project of the Municipal Academy of Agricultural Sciences (2023SLM04).
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