Optimization of sowing dates for enhanced rice yield: insights from field experiments in the middle and lower reaches of the Yangtze River, China.

An efficacious strategy to adapt to climate change involves optimizing the planting season, a technique that has been extensively utilized to enhance the use of solar radiation and temperature resources in rice cultivation. Field experiments were executed in the middle and lower reaches of the Yangtze River, China, employing three distinct rice cultivars and seven disparate sowing periods spanning 2019 to 2021. The objective of assessing the impact of sowing date on apparent radiation use efficiency (RUE_A), accumulated temperature use efficiencies (TUE), and overall rice yield. Subsequent to the delay of sowing dates, the duration of the comprehensive growth period initially exhibited a declining trajectory before subsequently escalating, with the reduction predominantly ascribed to a decrease in the number of days preceding heading. Furthermore, there was a tendency for both the mean daily and effective cumulative solar radiation to decline over the course of the growing period. The yield of the three rice varieties demonstrated an initial surge, which was then followed by a subsequent decline in reaction to the delay of sowing dates. A correlation analysis disclosed that solar radiation and effective cumulative temperature (EAT) were the predominant elements impacting grain yield. The outcomes of the path analysis indicate that EAT exerts the most substantial influence on yield, succeeded by cumulative total solar radiation (TSR), while photothermal quotient (PTQ) demonstrates the least impact on yield. There was a significant positive correlation between EAT and cumulative TSR with spikelets per panicle (0.237** and 0.218**), grain filling (0.753** and 0.576**), and grain weight (0.339** and 0.359**), respectively. The findings of this study indicate that an increase in yield is facilitated when the EAT after heading exceeds 594.9 ℃, the EAT surpasses 2016.7 ℃, the cumulative TSR before heading is above 1548.7 MJ m^- 2, the cumulative TSR after heading is over 603.0 MJ m^- 2, and the cumulative total radiation throughout the entire growth period is more than 2151.8 MJ m^- 2. Furthermore, the most optimal sowing date, as identified by this study, is June 6. This study provides key insights into boosting rice productivity in the middle and lower reaches of the Yangtze River, China by analyzing the impact of temperature and solar radiation on yield and identifying optimal growth conditions. Clinical trial number Not applicable.