Physiological Responses of Rice to CO2 Enrichment and Rising Temperature

摘要

The increase of atmospheric CO2 concentration, observed in recent years, will continue and may reach 550 ppm by 2050s. The increase of atmospheric CO2 has the potential to enhance the crop yields, as it is one of the main sources for plant photosynthesis. However, rising temperatures are likely to adversely affect physiology and development of crop. The integrated impacts on crops, caused by increases in atmospheric CO2 concentration and temperatures over the long term have not been clearly understood so far. CAAS designed the gradient experiment to reveal the effect of rising atmospheric CO2 and temperatures on growth, development and yield of rice (Oryza sativa L.) in Northern China. In this experiment, physiological characteristics of rice were measured during the season (after transplanting) in a half-open CO_2-temperature Gradient Chamber (CTGC). The CTGC was used to treat the rice crop with different CO2 concentrations and temperatures in the field. The results showed that, the grain fillingdry matter accumulation and yields increased signficantly at 550 ppm CO2 +1.0°C and 650 ppm CO2 +1.5°C compared to the CK. The harvest index (HI) at elevated CO2 was lower than that of CK. The treatments 550 ppm CO2 +1.0°C and 650 ppm CO2 +1.5°C increased the chlorophyll content of the rice leaves to 13.41 %-l6.74% above the CK (outside ambient plots), and increased further in later growth stages. The chlorophyll a/b ratio remained unaffected. The soluble sugar and soluble protein contents increasedin plants grown at 550 ppm CO2 +1.0°C and 650 ppm CO_2 +1.5°C compared to CK. The results indicate that CO2 fertilization effect also had potential to increase rice grain yield.