Effects of increased atmospheric CO2 on varieties of oat

The effects of elevated CO 2 were investigated on seven Scandinavian varieties of oat. Three landraces (before 1920), two varieties of intermediate-age (1920-1940), and two recent varieties (after 1940) were exposed to two atmospheric CO 2 concentrations (approx. 380 and 700 ppm). Elevated CO 2 increased the yield 7% on average but with large variation between varieties. The yield-response was variety specific and not related to the age of the variety. The mean seed number increased about 11%, with an increase in the landraces and diverging responses within the other age groups. The mean seed weight was reduced about 5.5%, with small changes within the landraces and diverging results within the two other age-groups. The mean dry biomass was increased about 20%; the landraces had a marked increase in dry biomass, while the response in the other varieties ranged from a large increase to a small decrease. These different responses among varieties provide a spectrum of trait-combinations desirable in breeding oats for different purposes. The quality of the seeds was not affected by the elevated CO 2 .