Soil Temperature and Phosphorus Supply Interactively Affect Physiological Responses of White Birch to CO 2 Elevation

Abstract

Phosphorus (P) is a common limiting nutrient element to plants and its supply and uptake by plants are strongly influenced by soil temperature. However, the interactive effects of the two factors on the physiological responses of plants to global change are poorly understood. In this study, we examined how P supply and Tsoil interacted in affecting physiological responses in white birch (Betula papyrifera) to [CO2]. We exposed seedlings to 7˚C, 17˚C and 27˚C Tsoil, 0.1479, 0.3029 and 0.5847 mM P2O5, and 360 and 720 µmol∙mol−1 [CO2] for four months. We have found that both the low soil temperature and CO2 elevation resulted in photosynthetic down regulation but the specific mechanisms of the down regulation were different between the two treatments, particularly the relative contributions of biochemical and photochemical capacity, mesophyll conductance and sink strength for carbohydrate utilization to the down regulation.