Response of rice to carbon dioxide and temperature

Abstract

The current increase in atmospheric carbon dioxide concentration ([CO 2]) along with predictions of possible future increases in global air temperatures have stimulated interest in the effects of [CO 2] and temperature on the growth and yield of food crops. This study was conducted to determine the effects and possible interactions of [CO 2] and temperature on the growth and yield of rice ( Oryza saliva L., cultivar IR-30). Rice plants were grown for a season in outdoor, naturally sunlit, controlled-environment, and plant growth chambers. Temperature treatments of 28/21/25, 34/27/31, and 40/33/37°C (daytime dry bulb air temperature/night-time dry bulb air temperature/paddy water temperature) were maintained in [CO 2] treatments of 330 and 660 μmol CO 2 mol −1 air. In the 40/33/37°C temperature treatment, plants in the 330 μmol mol −1 [CO 2] treatment died during stem extension while the [CO 2] enriched plants survived but produced sterile panicles. Plants in the 34/27/31°C temperature treatments accumulated biomass and leaf area at a faster rate early in the growing season than plants in the 28/21/25°C temperature treatments. Tillering increased with increasing temperature treatment. Grain yield increases owing to [CO 2] enrichment were small and non-significant. This lack of [CO 2] response on grain yield was attributed to the generally lower levels of solar irradiance encountered during the late fall and winter when this experiment was conducted. Grain yields were affected much more strongly by temperature than [CO 2] treatment. Grain yields declined by an average of approximately 7–8% per 1°C rise in temperature from the 28/21/25 to 34/27/31°C temperature treatment. The reduced grain yields with increasing temperature treatment suggests potential detrimental effects on rice production in some areas if air temperatures increase, especially under conditions of low solar irradiance.