2022 Volume 91 Issue 1 Pages 67-75
The brown rice quality in Akita Prefecture, Tohoku area Japan, decreased in 1999, 2010, and 2019 due to high temperatures during ripening, but the summer in Akita is too short to consider moving the cropping season as a countermeasure for the high temperature. In 2007 and 2010, we planted the rice cultivar Akitakomachi using two paddy transplanting methods; dense planting after a single application of fertilizer in nursery boxes to suppress nonproductive tillers (SNoPT) and uniform basal application of fertilizer to the top-soil and top-dressing at the meiosis stage as the conventional practice (Copr). The maximum temperature was 1.4 - 2.1°C higher in the plastic greenhouse during the ripening period than in the field. In 2007, the temperature was not considered high, but the irradiance was low. In 2010, the temperature was considered high. In SNoPT, the frequency of tillering at the 4-7th nodal position, which results in high yield and quality, was higher than that in Copr. The decrease in leaf color was smaller in SNoPT than in Copr. Furthermore, the percentage of chalky kernels in SNoPT in the field and in the greenhouse was 83% and 80%, respectively, of the values in Copr, although the differences were not significant. The yield and rice protein content in SNoPT were similar to those in Copr. These results suggest that SNoPT could be used as a countermeasure for high temperatures and low irradiance during ripening in the Tohoku area.
