Abstract:

The study aims to explore the effects of different sowing dates on the grain filling dynamics and final yield of winter wheat, reveal the relationship between sowing dates, environmental factors, and the growth and development of wheat, and provide a scientific basis for future winter wheat cultivation strategies to address climate change. Field experiments were conducted to systematically analyze the impacts of various sowing dates (early sowing on September 30 (E10), October 10 (CK), October 20 (L10), and October 30 (L20)) on the growth duration, effective accumulated temperature distribution, and grain filling characteristics of winter wheat. The Richards equation was employed to fit the grain filling data, followed by path analysis incorporating meteorological factors to evaluate their effects on wheat yield components. The results showed that: (1) as the sowing date was delayed, the key growth periods of wheat were also progressively delayed, particularly noticeable before winter, with the overall growth period being shortened by about 7-8 days for every 10-day delay; (2) the distribution of accumulated temperature varied significantly at different growth stages, with the effective accumulated temperature over the entire growth period decreasing from 2654.4°C for E10 to 2266.2°C for L20; however, for the October 20 (L10) sowing date, the accumulated temperature before winter remained at an adequate level; (3) the dry matter accumulation in grains exhibited an “S-shaped” growth trend, with the dry matter accumulation capacity of wheat sown on October 10 and October 20 being superior to that of the other treatments; the grain filling characteristics were influenced by both sowing dates and environmental factors, with distinct advantages in filling parameters for both early and late sowings; the late sowing treatment exhibited a higher grain filling rate, while the early sowing treatment showed better performance during the active grain filling period; (4) the highest yield of 719.21 g/m² was achieved with the October 20 (L10) sowing date. In conclusion, sowing date is a critical factor affecting the growth of winter wheat, significantly influencing the growth periods, grain filling, and final yield. In light of current climate change, delaying sowing date to around October 20 can effectively enhance yield.

Key words: winter wheat, sowing date, effective accumulated temperature, grain filling characteristics