Abstract
In cold regions, the duration between snow melting and sowing is short, which limits the scale of direct sowing on well-drained paddy fields. Here, we compared the growth and yield characteristics of rice directly sown in well-drained paddy fields in early winter before snow with those directly sown during the normal season (spring sowing). Although rice sown during early winter had a significantly lower seedling establishment rate and seedling number, they had earlier emergence date and higher plant height. Sampling in early July showed that rice sown in early winter had more vigorous growth than rice sown in spring; however, there was no significant difference in growth characteristics between the two groups in late July. Additionally, the heading and maturity dates of rice sown during early winter were 7 and 15 d earlier, respectively, than those of rice sown during spring. Moreover, there was no clear difference in yield and quality between early winter sowing and spring sowing. These results showed that direct seeding in well-drained paddy fields in early winter could be an effective method to increase rice yield in cold regions, and that an effective fertilization system in late July that takes advantage of the vigorous rice growth during this period may help increase yield.
