EFFECTS OF CARBON DIOXIDE AND PHOSPHORUS SUPPLY ON POTATO DRY MATTER ALLOCATION AND CANOPY MORPHOLOGY

Abstract

□ Data on combined effects of elevated carbon dioxide concentration (CO2) and phosphorus fertilization (P) on potato are scarce. Growth chamber studies (E1 and E2) that used three P and two CO2 levels were conducted. Leaf, stem, tuber, and stolon dry matter increased with P. Lateral-stem production was sensitive to P with a minimum 2.5-fold increase in mass. Leaf length increased an average 20.2% in E1 and 38.2% in E2 and leaf area increased an average 336% in E1 and 470% in E2 across CO2 levels. Tuber dry mass increased 22% in E1 and 38.2% in E2 in response to elevated CO2 and total dry mass by 14.1 and 15.4%. Tissue P contents increased with P but were unaffected by CO2. Effects of P on canopy branching were associated with plant N status. The studies suggest elevated CO2 levels are unlikely to alter potato P requirements on a unit mass basis.