[P1] Field Crop Production

[P1-04] Effect of Seed Maturity on Seedling Establishment in Early-Winter Direct-Sowing Cultivation In Rice

^○Seiji Oikawa, Kensaku Suzuki, Naoko Aikawa, Maya Matsunami, Hiroyuki Shimono (Department of Plant Biosciences, Faculty of Agriculture, Iwate University, Japan)

Early-winter Direct-sowing cultivation in rice is being put to practical use to extend the cropping season in cold regions. We examined the effect of seed maturity on seedling establishment in three rice cultivars ("Akitakomachi", "Hitomebore" and "Koshihikari") using seeds harvested at three different timing (20, 30, 40 days after heading, DAH). Seeds harvested 20DAH had a lower seedling establishment than seeds harvested 40DAH for all cultivars. The dormancy of seeds harvested at 40DAH tended to be higher than 20DAH in two out of three cultivars. In fact, we found seeds broken their dormancy (50℃, 7days) reduced the seedling establishment. The results showed that the well ripened seeds through the deeper dormancy might be suitable to Early-winter Direct-sowing cultivation in rice than un-ripened seeds.