Effects of elevated CO2 and O3 on tuber quality in potato (Solanum tuberosum L.)

This study examined the effects of season-long exposure to elevated carbon dioxide (CO2) and/or ozone (O-3) on tuber quality in potato (Solanum tuberosum L. cv. 'Bintje'). Stands of potato were grown to maturity in open-top chambers (OTCs) in 1998 and 1999 under a factorial combination of three CO2 (ambient, 550 and 680 mu mol mol(-1)) and two O-3 levels (ambient and elevated; 8 h per day seasonal means of 50 and 65 nmol mol(-1) in 1998 and 1999, respectively). The intermediate CO2 concentration was omitted from analysis of tuber quality. In 1999, the starch content of tubers and the viscosity of the resulting paste were increased by elevated CO2 (P < 0.05). Tuber nitrogen content was reduced by elevated CO2 in both years (P < 0.05), but nitrate content was decreased only in 1999 (P < 0.05). Elevated CO2 reduced citric acid content in 1998 (P < 0.05) and increased Vitamin C content in 1999 (P < 0.05). Elevated CO2 also tended to decrease the total glycoalkaloid content of tubers (P < 0.08) by decreasing their alpha -chaconine content. Elevated O-3 had less marked effects on tuber quality even though AOT40 values (accumulated O-3 exposure above a threshold of 40 nmol mol(-1)) of 12,461 and 27,113 nmol mol(-1) h were applied in 1998 and 1999, respectively. In 1998 the paste produced from tubers produced under elevated O-3 was more viscous (P < 0.05) and in 1999 the starch granules were less resistant to swelling (P < 0.05) than in tubers produced under ambient O-3. Total glycoalkaloid content was increased in 1999 because of an increase in a-solanine content (P < 0.05). No CO2 x O-3 interactions were detected for any of the quality parameters examined. The results are discussed in the context of the likely effects of predicted changes in climatic conditions on tuber quality. (C) 2001 Elsevier Science B.V. All rights reserved.