The effects of elevated concentrations of carbon dioxide and ozone on potato ( Solanum tuberosum L.) yield

Abstract

Potatoes ( Solanum tuberosum L. cv. ‘Bintje’) were grown in open top chambers at a site in the south-east of Ireland and exposed to ambient and elevated concentrations of CO 2 in combination with ambient and elevated concentrations of O 3 in the 1998 and 1999 growing seasons. Elevated concentrations of CO 2 (680 ppm) were supplied throughout day and night. Additional O 3 (50 ppb in 1998; 70 ppb in 1999) was added to ambient air to create elevated O 3 treatments. Exposure to elevated concentrations of O 3 caused visual damage to the leaves of the potato plants in both years of the study. In 1999, ozone damage to leaves was significantly reduced in the presence of elevated concentrations of CO 2. Stomatal conductance was reduced by elevated CO 2 and was reduced further by the elevated O 3 treatment under elevated CO 2. Exposure to elevated CO 2 increased tuber fresh weight yield by 32% in both years of the study. The yield increase was attributable to larger tuber sizes and not to an increase in the number of tubers. Tuber yield was unaffected by elevated O 3 at ambient concentrations of CO 2 in both years of the study. In 1999, the yield increase induced by elevated CO 2 was substantially reduced by the presence of elevated O 3. The reason for this phenomenon is unclear.