2023 Volume 92 Issue 3 Pages 209-219
Effects of cultivar and the environment in which the seeds were harvested on the seedling establishment after overwintering in early-winter direct-sowing cultivation of paddy rice were evaluated. We cultivated 60~72 combinations of cultivars and examined the effect of the environment in which the seeds were harvested on the seedling establishment after overwintering for three seasons at Iwate University. The observed seedling establishment range after overwintering was 0~64% in 2018/19, 0~33% in 2019/20, and 0~49% in 2020/21 depending on the combination of cultivar and the environment in which the seeds were harvested. The variation was relatively consistent over the years: there was a close correlation in seedling establishment between the years tested. An index of dormancy, the germination percentage measured on the 4th day after the start of incubation at 25°C in the germination test, was negatively correlated with the seedling establishment. This study provided a reference index to determine the appropriate dose of seeds to sow according to the cultivar and the environment in which the seeds were harvested for early-winter direct-sowing cultivation.
