Growth and quality responses of potato to elevated CO2

Root and tuber crops are highly important food resources. They comprise several genera and supply the main part of the daily carbohydrate intake of large populations. These carbohydrates are mostly starches found in storage organs, which may be enlarged roots, corms, rhizomes, or tubers. Food and Agriculture Organization (FAO) statistics indicate that in 2004 root and tuber crops were cultivated over more than 53 Mha and the total production was greater than 710 Mt (FAOSTAT 2004). Among these, potato (Solanum tuberosum L.) is the most cultivated species in the world, as its current cultivated area accounts for 36 % of the total harvested areas of root and tuber crops (FAOSTAT 2004). Potato also makes the largest contribution to the total production of tuber and root crops, representing 46 % of the global production of root and tuber crops (FAOSTAT 2004). Moreover, the yield per unit of potato steadily increased during the last 40 years passing from 12 th a -1 in 1961 to 17 t ha -1 in 2004 (FAOSTAT 2004). Among other factors (e.g. improved crop varieties, crop management, increased use of fertilisers, reduced losses from pest and disease infestations, improved harvesting and conservation methods, extended irrigation), the continuous increase in atmospheric carbon dioxide may also have contributed to these yield increases. The characteristics of potato source and sink organs and the transport capacity of assimilates seem to be important pre-requisites for a large CO 2 response. However, despite its economic and global importance and its expected strong response to increasing [CO 2 ], little research has been done on the potential effects of elevated [CO 2 ] on potato, especially if this is compared with that made on cereals and if we look at experiments performed under field conditions (i.e. free air CO 2 enrichment; FACE).