Abstract
AbstractThe exudation of root acid phosphatase (APase) is a plant response mechanism to phosphorus (P) deficiency. Under conditions of elevated CO2, P demand increases and possibly further enhances APase activity. We examined the activity of APase in 1‐year‐old ectomycorrhizal Pinus densiflora Sieb. et Zucc. seedlings grown in potted sand in the greenhouse under ambient (400 μmol mol–1) and elevated (700 μmol mol–1) CO2 with three modes of P supply: inorganic (NaH2PO4; Pin), organic (inositol hexaphosphate dodecasodium salt; Porg), and no phosphate (P0) for 78 d. Phosphorus limitations decreased P content in leaves and roots with lowest P content in P0 treatments, irrespective of CO2 conditions. However, P limitations decreased plant biomass at elevated CO2 levels, but not at ambient CO2 levels. The content in leaves of nutrients other than P was mostly unaffected by P supply, but decreased under elevated CO2. This observation was attributed to starch accumulation in leaves at elevated CO2, especially in the P0 treatment. The photosynthetic activity (expressed per unit of chlorophyll) was unaffected by P supply, but tended to be less at elevated CO2. There was no increase in root APase activity of Pinus densifolia in response to the P shortage caused by elevated CO2.
Published Version
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