Abstract: With the aim of forecasting the wheat-aphid relationships under different precipitation in the future atmospheric CO₂ environment,the effects of different atmospheric CO₂ concentration on Rhopalsiphum padi population under different soil water levels in Open-Top chambers were studied.The results showed that Rhopalsiphum padi population grew constantly with the continuous rising of atmospheric CO₂ and it grew more quickly when CO₂ concentration increased from 350μl·L^-1 to 550μl·L^-1 .In each CO₂ concentration treatment,R.padi population were distinct under different soil water level,and they were the highest under 60% of field water capacity treatment.When CO₂ concentration increased from 350μl·L^-1 to 550μl·L^-1 ,the increase of R.padi population under 60% of field water capacity treatment was higher than that under 40% and 80% treatment.When CO₂ concentration increased from 550μl·L^-1 to 700μl·L^-1 ,the increases of R.padi population under 60% and 40% soil water treatments were the same and both higher than that under 80% treatment.These results suggested that R.padi population would grow more quickly from the beginning to the middle of the 21st century and bring more damages to the wheat in arid and semiarid area.

Key words: Atmospheric CO₂ concentration, Soil water level, Spring wheat, Rhopalsiphum padi, Population increase, Damage tendency