Abstract: 【Objective】 In order to understand the response pattern of grain filling characteristics to sowing date and its relationship with thousand grain weight in wheat.【Methods】Twenty-one wheat varieties which were widely popularized or newly approved in Anhui Province were used as experimental materials with three sowing dates October 30（SD1）,November 14（SD2）and November 29（SD3）in 2018,were set up respectively. Split plot design was adopted in the experiment,the sowing date was the main area and the variety was the secondary area.【Results】The results showed that the grain filling rate of different sowing dates showed a single peak curve in the grain filling process.The growth rate was faster in the early stage of grain filling,and gradually slowed down in the later stage. The thousand grain weight decreased significant with the delay of sowing date in each sampling period.Before May 12,the grain filling rate of SD1 was significantly higher than that of SD2 and SD3,and after May 17,the grain filling rate of SD2 and SD3 were significantly higher than that of SD1,and there was no significant difference in harvest time. The thousand grain weight and grain filling rate of different varieties in different sampling periods were different in three sowing periods.Ningmai 21 and Xinmai 26 had higher thousand grain weight than most varieties in each sampling period during the three sowing dates,and the grain filling rate was first high and then gradually decreased. The thousand grain weight of Weilai0818 in different filling periods was lower than that of most varieties,and the grain filling rate was first low and then increased slightly in three sowing periods. Correlation analysis indicated that there was a positive correlation between grain filling rate and thousand grain weight in the early and middle stages of grain filling under different sowing dates,among which the grain filling rate on 17^th May was significantly positively correlated with thousand grain weight at different sowing dates. However,there was no significant correlation between grain filling rate and thousand grain weight in the late stage of grain filling.【Conclusion】In the process of grain filling under different sowing dates,the grain filling rate in the early and middle stages of grain filling rate has a greater impact on the thousand grain weight. The thousand grain weight of each sampling period gradually decreased significant with the delay of sowing date. In the early and middle stages of grain filling,the grain filling rate decreased with the delay of sowing date.In the later stage of grain filling,the grain filling rate increased with the delay of sowing time. Increasing the grain filling rate in the early and middle stages of grain filling can effectively increase the thousand grain weight.

Key words: Wheat, Sowing date, Grain filling rate, Thousand grain weight