Legume Genomics and Genetics 2025, Vol.16, No.6, 279-287 http://cropscipublisher.com/index.php/lgg 282 lupin, wider row spacing and lower density will result in more chlorophyll in the leaves and heavier seeds per plant, indicating that the conditions between plants are loose and the grains develop more evenly (Jańczak-Pieniążek et al., 2023). If the density is too high, the plants will compete more fiercely for light and fertilizer, and the nutrients will be unevenly distributed, which will easily lead to a widening gap in seed size and quality. 4.3 Sowing density and its impact on seed viability and germination Density also affects the vitality and germination of seeds in the later stage. Wheat experiments show that high density can increase the total yield, but it will reduce seed vitality and germination rate, which is more obvious in varieties with high vitality (Zucareli et al., 2021). The results of rapeseed are similar: when the density is set in a moderate range, the survival rate of seedlings is high and the agronomic traits are good; when the density is increased, the quality of seedlings decreases, and the survival rate after transplanting is also low (Zuo et al., 2022). Therefore, in order to maintain high seed vitality and high germination, the sowing density must be stuck in an appropriate range, neither wasting resources nor adding burden to the seedlings. 5 Interaction with Environmental and Agronomic Factors 5.1 Role of soil fertility and irrigation practices The quality of the soil and the amount of water will directly affect the effect of sowing density. Sowing density, soil type and fertilization method will affect each other, and the impact on quality is often greater than the impact on yield. To achieve high yields, it depends on the proper combination of soil and climatic conditions in specific areas (Cammarano and De Santis, 2024). How much rain and whether there are enough water resources, especially during the critical period of crop growth, are key factors in determining high-density or low-density yield performance (Mumford et al., 2023). For example, the amount of nitrogen fertilizer and when it is applied will interact with density and work together on yield and quality. Therefore, in order to increase yield, water and fertilizer management cannot be considered separately, but must be combined together. 5.2 Influence of climate zones and seasonal variation Climate conditions, such as temperature, rain and sunshine, are the most important external factors affecting the performance of planting density (Arif et al., 2023). Seasonal changes can also make a big difference. Some varieties or management methods work better in certain weather conditions (Nsarellah et al., 2024). For example, if the climate is mild and water is sufficient, it may be easier to get high yields by planting densely; but in places with dry and hot weather and prone to water shortages, too high a density may not be as good as planting sparsely (Howard et al., 2017). The relationship between density, variety, climate and management measures is very complex. Many studies now use predictive models to take environmental parameters into account to help determine which density is appropriate in what season and climate conditions. 5.3 Integration with other agronomic practices such as fertilization and pest control Density cannot be determined alone. It must be considered together with management measures such as fertilizer use and pest and disease control to ensure stable production and quality. In particular, nitrogen fertilizer application has a strong linkage with density, which not only affects yield but also has an impact on the environment. The amount of fertilizer and the time of fertilization are the most influential pair of matching factors (Van Eeuwijk et al., 2001). Pest and disease control measures will also interact with density. Sometimes high density makes pests and diseases more likely to occur; but this is not necessarily the case, depending on the crop type and local conditions (Schulzova et al., 2023). Therefore, in actual production, it is best to combine density, fertilization and pest and disease control according to the specific situation and formulate a suitable management plan. This will maximize yield while minimizing the impact on the environment. 6 Genotypic Response to Sowing Density 6.1 Variation in density response among different soybean cultivars Different varieties of soybeans perform very differently when they encounter high density. Field and indoor experiments have found that the three types of genotypes - determinate, semi-determinate and indeterminate - will
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