Photosynthetic acclimation to elevated CO2 is modified by source:sink balance in three component species of chalk grassland swards grown in a free air carbon dioxide enrichment (FACE) experiment

• Published in: Plant, cell and environment cell and environment, 1998-02, Vol.21 (2), p.159-168
• Main Authors: Bryant, J., Taylor, G., Frehner, M.
• Format: Article
• Language: English
• Subjects: Agricultural and forest climatology and meteorology. Irrigation. Drainage; Agricultural and forest meteorology; Agronomy. Soil science and plant productions; Animal and plant ecology; Animal, plant and microbial ecology; Anthyllis vulneraria L; Biological and medical sciences; Bromopsis erecta (Hudson) Fourr; Climatic adaptation. Acclimatization; Economic plant physiology; elevated CO2; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Net assimilation, photosynthesis, carbon metabolism. Photorespiration, respiration, fermentation (anoxia, hypoxia); Nutrition. Photosynthesis. Respiration. Metabolism; photosynthesis; Sanguisorba minor Scop; source:sink; Synecology; Terrestrial ecosystems
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1046/j.1365-3040.1998.00265.x

Artificial chalk grassland swards were exposed to either ambient air or air enriched to 600 μmol mol–1 CO2, using free‐air CO2 enrichment technology, and subjected to an 8 week simulated grazing regime. After 14 months of treatment, ribulose‐1,5‐bisphosphate carboxylase (Rubisco) activity (Vc,max) and electron transport mediated ribulose‐1,5‐bisphosphate (RuBP) regeneration capacity (Jmax), estimated from leaf gas exchange, were significantly lower in fully expanded leaves of Anthyllis vulneraria L. (a legume) and Sanguisorba minor Scop. grown in elevated CO2. After a change in source:sink balance brought about by defoliation, photosynthetic capacity was fully restored in A. vulneraria and S. minor, but acclimation continued in the grass Bromopsis erecta (Hudson) Fourr. Changes in net photosynthesis (Pn) with growth at elevated CO2 ranged from a 1·6% reduction in precut leaves of A. vulneraria to a 47·1% stimulation in postcut leaves of S. minor. Stomatal acclimation was observed in leaves of A. vulneraria (reduced stomatal density) and B. erecta (reduced stomatal conductance). The results are discussed in terms of whole‐plant resource‐use optimization and chalk grassland community competitive interactions at elevated CO2.