Interactions of CO 2 enrichment and temperature on carbohydrate accumulation and partitioning in rice

Abstract

The objective of this study was to determine the long-term effects of CO 2 concentration and temperature on carbohydrate partitioning and status in rice ( Oryza sativa L. cv. IR-30). The plants were grown season-long in sunlit, controlled-environment chambers with CO 2 concentrations of 330 or 660 μmol mol −1, and daytime air temperatures of 28, 34 or 40°C. In leaf blades, the priority between partitioning of carbon into storage or into export changed with CO 2 concentration and temperature. Leaf sucrose concentration increased with CO 2 enrichment at all temperature regimes. Over the season, elevated CO 2 resulted in an increase in total non-structural carbohydrate (TNC) concentration in leaf blades, leaf sheaths and culms at all temperature treatments. Elevated CO 2 had no effect on carbohydrate concentration in the grain at maturity, however, grain TNC concentration was significantly lowered by increasing temperature. Under the highest temperature regime, the 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. The results suggest that CO 2-enriched plants could survive and maintain carbohydrate production rates at higher temperatures than the non-enriched plants; however, the optimum temperature for TNC accumulation was 28°C at both CO 2 concentrations.