Direct and maternal effects of elevated CO2 on early root growth of germinating Arabidopsis thaliana seedlings

Individuals of Arabidopsis thaliana, collected in different natural populations, were grown in controlled and elevated CO2 in a glasshouse. Following germination, root growth of progeny of different lines of these populations was studied in control and elevated atmospheric CO2. No significant direct effect of atmospheric CO2 concentration could be demonstrated on root growth. An important parental effect was apparent, namely that root length and branching were decreased in seeds collected from a mother plant which had been grown in elevated CO2. This was correlated with smaller seeds, containing less nitrogen. These parental effects were genetically variable. We conclude that CO2 may affect plant fitness via parental effects on seed size and early root growth and that the genetic variability shown in our study demonstrates that Arabidopsis populations will evolve in the face of this new selective pressure. (C) 1998 Annals of Botany Company.