Modeling the effects of water temperature on rice growth and yield under a cool climate: II. Model application

Abstract

Impact of water temperature (Tw) on rice growth and yield in Hokkaido, Japan, one of the coolest rice producing areas in the world, were quantitatively evaluated using the newly developed growth model that can simulate the effects of Tw independently from the effects of air temperature (Ta). Using this model, first we evaluated the benefits of having Tw warmer than Ta for rice yield. Without this difference, simulated rice yield was reduced by almost half. Second, the model also highlighted the causes of differences among sites in rice productivity; higher productivity was attributed to higher solar radiation (RD), higher wind speed (WS), and higher Tw. Finally, under a scenario of future global warming, the model estimated that a 3°C Ta increase above the current level increased Tw by 1°C and increased yield by 6%. However, adding the effects of changes in other factors (RD and WS) increased Tw by 0 to 2°C and changed yield by -30% to +41%. Our results demonstrate that Tw must be considered to understand growth and yield responses of rice to climate change, especially in cool regions. © American Society of Agronomy.