Abstract
Maps for forecasting heading dates of the forage rice cultivars ‘Bekogonomi’ and ‘Yumeaoba’, direct-seeded in paddies in the Tohoku region were created by using models to estimate the developmental stages of rice plants, and 1-km-mesh temperature data. The developmental-stage models were prepared by using growth and temperature data obtained from the experiments held in several different cropping seasons in Morioka, in the north central region of Tohoku. Heading dates with respect to direct seeding dates were predicted by using these models. The root mean square error (RMSE), quantified by the difference between the predicted heading dates and the observed ones, was 1.8 to 2.8 days. Inclusion of data from two other locations where the climatic conditions differed from those at Morioka increased this error to only 1.9 to 3.1 days. The heading dates of every 1-km mesh, as predicted from the daily mean temperatures in a normal year, were successfully displayed on the maps of the Tohoku region. Information about heading dates on these maps can help farmers to select cultivars and coordinate crop schedules to suit their local climatic conditions and farming practices. Furthermore, by using the daily mean temperature of the normal year, heading dates on the maps can be corrected appropriately to that in the year and work schedule may also be corrected.
