Effect of CO2 Enrichment on the Translocation and Partitioning of Carbon at the Early Grain-filling Stage in Rice (Oryza sativa L.)

Abstract

Rice plants (Oryza sativa L.) were grown under normal (350 µL L-1 CO2) and CO2-enriched (660 µ L L-1 CO2) conditions, and 13CO2 was supplied to the rice plants after heading to examine the translocation and partitioning of photosynthate at the early grain-filling stage. At 2 days after supplying 13CO2, no difference in the 13C content of the whole plant was observed between the plants grown under normal and CO2-enriched conditions, but translocation of 13C from the leaf blade to other plant organs seemed to be accelerated by CO2 enrichment. Up to 9 days after supplying, 13CO2 fixed into sucrose was mainly used to synthesize starch in the stem rather than translocated to the ear in plants grown under normal conditions. In contrast, the supplied 13C was rapidly translocated to the ear, and 13C stored as starch in the stem was also translocated to the ear in plants grown under CO2-enriched conditions. Therefore, we concluded that CO2 enrichment accelerated the translocation of carbohydrates to the ear.

Keywords

• 13C
• CO2 enrichment
• Grain-filling
• Partitioning
• Rice
• Sink
• Translocation