Effects of Atmospheric CO2 Concentration, Phosphorus Nutrition and Night Temperature on Growth and Yield of Rice.

Rice plants were grown in artificially illuminated growth cabinets under conditions of ambient CO2 concentration, 28/23, 12-hr day/l2-hr night temperatures, and 3 or 300M phosphorus in a standard nutrient solution with soil. At the 10-leaf stage, atmospheric CO2 (350 or 700mol mol-1) and temperature (28/23 or 28/28) were controlled and maintained until the harvest at 40 days after heading. At 28/23, the high phosphorus accelerated heading by 2-3 days while the high CO2 accelerated heading only by one day. Culm and panicle lengths were not affected by high CO2, but they increased under high phosphorus. Panicle numbers were greater in both high CO2 and high phosphorus. Panicle weight increased 20 and 40% at low and high phosphorus, respectively, in the high CO2 treatments without amelioration of the harvest index (ca. 0.5). In 28/28-