, Volume 104-105, Issue 1, pp 413-419

Effects of elevated CO2 on growth, photosynthesis and respiration of sweet chestnut (Castanea sativa Mill.)

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Abstract

Two year old sweet chestnut seedlings (Castanea sativa Mill) were grown in pots at ambient (350 µmol·mol−1) and double (700 µmol·mol−1) atmospheric CO2 concentration in constantly ventilated greenhouses during entire growing seasons. CO2 enrichment caused either no significant change or a decrease in shoot response, depending on yearly weather conditions. Similarly, leaf area was either reduced or unchanged under elevated CO2. However, when grown under controlled conditions in a growth chamber, leaf area was enlarged with elevated CO2.

The CO2 exchanges of whole plants were measured during the growing season. In elevated CO2, net photosynthetic rate was maximum in May and then decreased, reaching the level of the control at the end of the season. End of night dark respiration of enriched plants was significantly lower than that of control plants; this difference decreased with time and became negligible in the fall. The original CO2 level acted instantaneously on the respiration rate: a double concentration in CO2 decreased the respiration of control plants and a reduced concentration enhanced the respiration of enriched plants. The carbon balance of a chestnut seedling may then be modified in elevated CO2 by increased carbon inputs and decreased carbon outputs.