GROWTH, GRAIN-YIELD AND QUALITY OF RICE (ORYZA-SATIVA L.) IN RESPONSETO ELEVATED CO2 AND PHOSPHORUS-NUTRITION (REPRINTED FROM PLANT NUTRITION FOR SUSTAINABLE FOOD-PRODUCTION AND ENVIRONMENT, 1997)

The influence of rising atmospheric CO2 concentrations and phosphorus nutrition on growth, grain yield and quality of a early maturing rice cultivar (Oryza sativa L. cv. Jarrah) was investigated by growing plan ts in a range of phosphorus levels at tither 350 or 700 mu L CO2 L-1 i n the growth chambers. Total above ground biomass and grain yield were greater at elevated CO2 concentrations and with increasing phosphorus supply. The CO2 response was evident at all but the lowest phosphorus treatments but its magnitude was greater at moderate phosphorus suppl ies. The increase in grain yield at high CO2 was due mainly to an enha ncement of tiller number. The phosphorus concentration in the foliage was unaffected by CO2 enrichment and the critical concentration of 1.8 g kg(-1) dwt was the same as reported for field-grown rice. The conce ntration of calcium in the foliage was increased by high CO2 and the n itrogen concentration was reduced, Chemical analysis (amylose and mine ral concentration) indicated that cooked rice grain from high-CO2-grow n plants would be firmer and that concentrations of Zn and Fe, which a re important in the diet of humans, will be lower. These results indic ate that there is a need to plan for the inevitable rise in global CO2 concentrations by selecting cultivars which will be more productive a nd yet maintain suitable quality characteristics under elevated CO2 le vels.