Germination of CO2-enriched Pinus taeda L. seeds and subsequent seedling growth responses to CO2 enrichment

1. Pinus taeda seeds, developed under ambient or elevated (ambient + 200 mu l l(-1)) [CO2], were collected from Duke Forest, North Carolina, USA in Oct ober 1998. Seeds were germinated in nutrient-deficient soil in either ambie nt or elevated [CO2] (ambient + 200 mul l(-1)) greenhouse chambers and allo wed to grow for 120 days. 2. Seeds that developed in elevated [CO2] had 91 and 265% greater weight an d lipid content, respectively, and three times the germination success, com pared to those developed in current ambient [CO2]. 3. Seedlings from the elevated [CO2] seed source had significantly greater root length and more needles regardless of greenhouse chamber, but there we re no treatment effects on tissue or total biomass. 4. Severely limiting nutrient conditions resulted in significant photosynth etic downregulation by seedlings grown in greenhouse chambers with elevated [CO2], regardless of seed source. 5. Our hypothesis that greater seed reserves from CO2 enrichment would syne rgistically affect seedling growth responses to elevated [CO2] was not stro ngly supported. Nonetheless, seeds produced in a CO2-enriched environment m ay have fundamental changes in their viability, chemistry and germination t hat may affect reproduction.