Generative development of barley at an elevated atmospheric concentration of CO2 and varying temperature conditions

Ear development in barley (Hordeum vulgare L.) was studied at normal (350 mu l/l) and elevated (700 mu l/l) atmospheric CO2 concentrations and two temperature regimes. Plant productivity was found to increase by 63 and 47% at temperatures of 20/14 and 23/17 degrees C (day/night), respectively. Analysis of production showed that elevated CO2 may induce an increase in the number of spikelets in the inflorescence primordium and in the size of the primordium beginning from the early stages of development. At 20/14 degrees C, a high level of CO2 significantly elevated the yield of the main ear, increasing the number of caryopses by 18-28% and the grain weight in the main ear by 42-49%. At 23/17 degrees C, a double concentration of CO2 increased plant production due to increased tiller formation (by 75-106%). It was found that the CO2 concentration did not affect pollen fertility in barley at low temperature, but at elevated temperature, the number of sterile pollen grains increased. Thus, the experiments showed that an elevated CO2 concentration affected the development of the barley ear during its whole ontogeny, including the early stages.