Impact of field drying at different initial leaf ages on growth and yield formation of direct seeding rice in Chengdu plain

Abstract To determine the optimal drying period for direct seeding rice, we conducted experiments using two rice cultivars: hybrid indica (Shuyou 217) and conventional indica (Huang Huazhan). The experiments explored the influence of varying initial leaf development stages on tillering dynamics, leaf area, dry matter production, yield, and yield components in direct seeding rice. The results indicated a significant correlation between the initial leaf development stage and the yield of direct seeding rice. As the initial leaf development stage progressed, the number of effective panicles increased, while key traits affecting panicle yield, such as grain/spikelet? Number per panicle, seed setting rate, and 1000-grain weight, decreased. Additionally, varietal differences in tillering reduction were observed across different leaf development stages. Shuyou 217 exhibited a decrease in heading rate with increasing leaf development stage, whereas Huang Huazhan showed no significant difference. With delayed seeding planting age, both cultivars demonstrated an increasing trend in the leaf area index, initially leading to a rise in effective leaf area proportion, followed by a decline. At the full heading and maturity stages, the dry weight of the stem sheath and panicles per plant decreased as the leaf development stage was delayed. However, the output and transport rates of stem sheath assimilated first increased and then decreased. From a practical perspective, field drying management should be aligned with varietal characteristics to reduce ineffective tillering, ensure sufficient dry matter accumulation during the full heading stage, and optimize post-heading dry matter export and transport. This strategy promotes the coordination between the “source” and “sink” dynamics in rice, ultimately maximizing yield in direct-seeded rice systems.