Changing sink and source relations in rice (Oryza sativa L.) using carbon dioxide enrichment in the field

Rice plants in the field were enclosed in chambers covered with mylar film and subjected to CO² enrichment for 30 days before or after flowering. The CO² enrichment was intended to increase grain number (sink size) befiore flowering, and to increase photosynthesis of a canopy (source) after flowering.

The CO² enrichment before flowering increased grain number per unit land area and grain weight. The enrichment after flowering did not affect grain number but increased filled-grain percentage and grain weight. As a result, both treatments increased grain yield. Analysis of yield components indicates that a major factor responsible for the yield differences is grain number. It was also shown that the increase in yield was directly proportional to the dry matter increase after panicle initiation.

The CO² enrichment before flowering increased grain number per unit land area and grain weight. The enrichment after flowering did not affect grain number but increased filled-grain percentage and grain weight. As a result, both treatments increased grain yield. Analysis of yield components indicates that a major factor responsible for the yield differences is grain number. It was also shown that the increase in yield was directly proportional to the dry matter increase after panicle initiation.