Factors Responsible for Regional Variation of Cold Tolerance in Rice in Northern Japan

Abstract

The effects of climate conditions during vegetative growth on cold tolerance of rice at the booting stage were examined. Rice cultivar ‘Hitomebore’ was grown in Hokkaido-Tohoku region at six locations in 2008 and seven locations in 2009, where the soil and applied fertilizer were identical. A cold tolerance test was conducted during the reproductive growth after panicle formation under deep cold water conditions. The sterility significantly varied with the location in both years. It was closely and negatively correlated with air and water temperatures before the panicle formation stage. These results indicate that the air and water temperatures before panicle formation can explain the variation of cold tolerance and that a lower temperature during the vegetative growth stage decreases the cold tolerance.