Abstract
In the Hokuriku region, direct seeding tends to be more common in inland areas than in coastal areas. One reason may be the sea breeze in coastal areas, which can delay or suppress the rise in daytime air temperature. In addition, seedling emergence and the early growth of direct-seeded rice in the coastal area may be influenced by the narrow daily temperature range between daytime and nighttime, even if the mean daily temperature is the same as in the inland areas. In this study, the growth of potted plants in a windbreak plot was compared with that in a non-windbreak plot (control) under outdoor conditions. In the windbreak plot, in which the maximum temperature was high and the daily temperature range was wide, the seedling emergence and establishment rates were higher than those in the control plot. We also investigated seedling emergence and establishment of direct-seeded rice grown under different mean air temperatures and daily temperature ranges using germinated seeds in a temperature-controlled incubator. Our results indicated that the influence of the daily temperature range after seeding was greater under low-temperature conditions than under high-temperature conditions. Under low-temperature conditions, early growth was better with a wide daily temperature range than with a narrow daily temperature range. Moreover, the change with time in the measured value of seedling emergence rate and that estimated by the Arrhenius equation were approximately the same.
