The effects of CO2 and O3 singly and in-combination on Malaysia rice cultivar (MR 221)

The continuous burning of fossil fuel and rapid development of industrialization have increase the atmospheric Carbon dioxide (CO2) and tropospheric Ozone (03). The profound effects of the rising CO, and 03 in the tropospheric environment on the plants have been acknowledged due to the combination effects of CO, and 03 on plants. The seedling rice (Oryza sativa) of Malaysian cultivar (MR221) were exposed to four types of treatments namely 350 ppm C02 and 10 ppb 03 conditions, 660 ppm C02 and 10 ppb 03, and 350 ppm CO, and 33 ppb 03. The seedlings were exposed to these conditions 6 hours per day from 0900 to 1500 hours for 5 days per week for more than three months. The objectives of this study was to determine the direct effects of elevated CO, and 03 enhancement on physiological aspects and growth performances of rice. The results indicated that there was a progressive stimulation in photosynthesis of seedlings exposed to elevated C02 indicates by doubling of Pmax. Results of the growth performances showed that there were no consistent effects of ozone on plant height and tillering which differ from other related studies. (Author)