more importantly, these parameters can be precisely controlled to create the environmental conditions desired. for example, the temperature of the chamber block is controlled by peltier coolers to any level within +- 6 c of the air temperature. light can be adjusted at any level from 0 to more than 2000 umol m-2 s-1, and co2 from 0 to 200 umol as well. artifical light is optionally supplied by a "cold" lamp (LED type,670 nm) . the selected level of co2 are supplied by a co2 injector system. any combination of light and co2 level can also be measured with an optional sensor.