POA ANNUA SHOWS INTERGENERATIONAL DIFFERENCES IN RESPONSE TO ELEVATEDCO2

Inter-generational effects on the growth of Poa annua (L.) in ambient and elevated atmospheric CO2 conditions (350 and 550 mu l l(-1), respe ctively) were studied in two different experiments. Both experiments s howed similar results. In a greenhouse experiment growth, measured as the numbers of tillers produced per week, was compared for plants grow n from first and second generation seeds. Second generation seeds were obtained from plants grown for one whole generation in either ambient or elevated atmospheric CO2 ('ambient' and 'elevated' seeds, respecti vely). First generation plants and second generation 'ambient' plants did not respond to elevated CO2. Second generation 'elevated' plants p roduced significantly more tillers in elevated CO2. In the second expe riment model terrestrial ecosystems growing in the Ecotron and which i ncluded Poa annua were used. Above-ground biomass after one and two ge nerations of growth were compared. At the end of Generation 1 no diffe rence was found in biomass production while at the end of Generation 2 biomass increased in elevated CO2 by 50%. The implications for climat e change research are discussed.