Rice Genomics and Genetics 2025, Vol.16, No.2, 71-85 http://cropscipublisher.com/index.php/rgg 75 high, and the incidence of diseases such as rice blast and sheath blight often increases. Therefore, when optimizing density, both plant stress resistance and field hygiene conditions must be taken into account. It is generally recommended to moderately reduce the basic seedling density or use wide and narrow rows to improve ventilation and light transmission in an environment prone to lodging and disease, so as to improve the robustness of the group. Planting density affects rice tillering dynamics, plant height and plant type, leaf area index, and stem strength, thereby shaping different group growth characteristics. Appropriate density can promote the balanced growth of rice populations and enhance the photosynthetic performance and stress resistance of the population; too dense or too sparse will break this balance. The former will lead to internal consumption of the population and inhibited individual development, while the latter will cause waste of resources and insufficient population effect. Therefore, in cultivation practice, the tillering and plant type characteristics should be dynamically monitored during the growth period, and density-related measures (such as thinning and replanting) should be adjusted in a timely manner to form an ideal population growth and development situation and lay the foundation for high yield. Figure 1 Tillers and percentage of productive tillers of rice affected by increased seeding density and seedling age with crop straw boards for seedling cultivation. (A) Tillers and percentage of productive tillers of rice in 2021. (B) Tillers and percentage of productive tillers of rice in 2022 (Adopted from Ling et al., 2024) 4 Impact on Yield and Its Components The level of rice yield depends on three main components: the number of effective panicles, the number of grains per panicle and the thousand-grain weight. Changes in planting density will have a significant effect on the final yield by affecting the above factors. Density will also affect rice quality and nutrient utilization efficiency.
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