Optimizing Seeding Rate and Seedling Age Enhances Seedling Quality, Lodging Resistance, and Yield in Cold‐Region Rice Production Using Pot‐Tray Mat Seedling

ABSTRACT

Seeding rate and seedling age are key cultivation factors affecting rice seedling quality, lodging resistance, and grain yield. In recent years, the pot‐tray mat seedling technique has demonstrated significant potential for producing robust seedlings and increasing the yield in the middle and lower reaches of the Yangtze River. Meanwhile, in cold‐region rice production systems characterized by limited heat resources, the interactive effects of seeding rate and seedling age within this technique on comprehensive seedling quality, lodging resistance, and grain yield remain unclear. To address this, a field experiment was conducted using the cold‐region japonica rice cultivar Longken 2021 with conventional mat seedling as the control (CK). Four seeding rates (60, 80, 100, and 120 g tray ⁻¹ , denoted as R1, R2, R3, and R4, respectively) were combined with three seedling ages (35, 40, and 45 days, denoted as A1, A2, and A3, respectively). The results indicated that the pot‐tray mat seedling method significantly improved seedling quality compared to the conventional CK, and the combination of low seeding rate and long seedling age (R1A3) increased stem base width and seedling plumpness by 45.8%–46.2% and 11.8%–19.0%, respectively, relative to CK. Regarding lodging resistance, the pot‐tray mat seedling method improved stem mechanical properties, and treatments with medium seeding rate and medium seedling age (R2A2 and R3A2) increased the section modulus by 16.5%–24.4% and decreased the lodging index by 15.2%–22.2% compared to CK. For grain yield, the highest values were achieved under the medium seeding rate with medium seedling age (R2A2 and R3A2), which increased yield by 9.2%–24.2% over CK. Although low seeding rates enhanced seedling quality, insufficient basic seedling numbers reduced the number of effective panicles, limiting yield potential. In summary, under the pot‐tray mat seedling system for cold‐region rice, a low seeding rate combined with a long seedling age favors the cultivation of robust seedlings, while a medium seeding rate combined with a medium seedling age achieves a better balance between seedling vigor and population growth structure, thereby significantly enhancing stem lodging resistance and increasing grain yield. Therefore, considering seedling quality, lodging resistance, and yield performance, the combination of a medium seeding rate and a medium seedling age is recommended as the optimal strategy for pot‐tray mat seedling production in cold‐region rice, providing a theoretical basis and technical support for high‐yield and stress‐resistant cultivation.