Legume Genomics and Genetics 2026, Vol.17, No.1, 68-79 http://cropscipublisher.com/index.php/lgg 77 Additionally, temporal variability in plant emergence was not addressed; previous work suggests that non-uniform emergence timing can negatively impact yield even at optimal densities (Masino et al., 2018). Future research should incorporate broader environmental gradients and multiple genotypes to better understand how planting density interacts with genetic traits under variable climatic conditions. Investigating the combined effects of spatial distribution uniformity, nutrient management, irrigation regimes, and intercropping practices will provide more comprehensive recommendations for sustainable soybean production. Advanced modeling approaches integrating physiological parameters could also improve predictions of optimal density ranges tailored to specific regions. Addressing these gaps will enhance precision agriculture strategies aimed at maximizing soybean growth efficiency and yield stability. 8 Conclusions and Recommendations This study confirms that planting density plays a critical role in determining soybean growth, canopy structure, resource use efficiency, and ultimately yield. Increasing planting density generally enhances leaf area index, dry matter accumulation, and canopy light interception, which contribute to higher seed yields under optimal conditions. However, excessively high densities can intensify intraspecific competition for light, water, and nutrients, leading to reduced individual plant performance and potential yield penalties if not managed properly. Uniform plant distribution combined with moderate to high densities improves population uniformity and reduces variability in seed weight among plants, further boosting overall yield. Additionally, environmental factors such as water availability and nitrogen supply interact with planting density to influence photosynthetic capacity and biomass production. These findings highlight the complex balance between maximizing population size and minimizing competition stress to optimize soybean productivity. Optimal planting density varies depending on environmental conditions, cultivar traits, and management practices. In general, densities around 180,000 to 270,000 plants per hectare are recommended for achieving high yields in favorable environments when combined with uniform spacing and adequate nutrient and water supply. For example, a 20-60 cm row spacing configuration at high density improved canopy light environment and photosynthetic efficiency, resulting in yield increases of up to 5.9% compared to equidistant planting. In lower-yield or stress-prone environments, higher densities may be necessary to compensate for reduced individual plant performance. Cultivar selection also matters; varieties with fewer branches tend to perform better under close planting due to greater tolerance of crowding. Practical implications include adopting uniform plant spacing techniques and adjusting row configurations to optimize light penetration while avoiding excessive competition that can reduce lodging resistance or increase disease risk. Future research should explore broader environmental gradients and genotype-by-environment interactions to refine optimal planting density recommendations across diverse agroecosystems. Investigations into the combined effects of spatial distribution uniformity, nutrient management strategies (including nitrogen rates), irrigation regimes, and intercropping systems will provide more holistic insights into sustainable soybean production. Additionally, studies on the role of plant growth regulators like DA-6 in mitigating high-density stress show promise for enhancing branching architecture and yield under dense planting conditions. Incorporating advanced modeling approaches that integrate physiological parameters could improve prediction accuracy for site-specific density optimization. From an agricultural practice perspective, promoting precision planting technologies that ensure uniform spacing alongside tailored nutrient and water management will be key to maximizing soybean growth efficiency and yield stability. Acknowledgments I would like to thank the anonymous reviewers for their detailed review of the draft. Their specific feedback helped us correct the logical loopholes in our arguments. Conflict of Interest Disclosure The author affirms that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.
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