2021 Volume 90 Issue 3 Pages 269-276
The dormancy of rice (Oryza sativa L.) seed varied by cultivar and year, and seed preparation using the conventional method often resulted in uneven germination. Therefore, we investigated the appropriate soaking conditions for securing uniformly germinated seeds by altering the temperature and duration of the soaking period. At the soaking temperature of 10°C or 12°C, the germination rate was 90% or greater when the accumulated temperature was 120°C or more for “Koshihikari” and 80°C or more for “Koshiibuki; and, the longer the duration of soaking, the higher was the germination rate of the deeply dormant “Gohyakumangoku”. When the soaked seeds were germinated in nursery soil, the longer the duration of soaking before sown in nursery soil, the percentage of normally germinated seeds was higher, and the length of the shoots was longer. However, at a soaking temperature of 5°C, the germination rate was less than 90% for “Koshihikari” and “Koshiibuki” and 50% for “Gohyakumangoku” regardless of the duration of soaking. The expression of α-amylase for each isoform was examined by western blotting after soaking at different temperatures and durations. AmyII-4 expression was observed at both 12°C and 5°C, but the transition of the expression during soaking varied with water temperature.
