Carbon assimilation and nitrogen in needles of fertilized and unfertilized field-grown Scots pine at natural and elevated concentrations of CO2.

摘要: Effects of elevated CO 2 concentration ([CO ]) on carbon assimilation and needle biochemistry fertilized unfertilized 25-30-year-old Scots pine (Pinus sylvestris L.) trees were studied in a branch bag experiment set up naturally regenerated stand. In each tree, one was enclosed supplied with ambient [CO ] (360 μmol mol −1 ), second (680 ) control left unbagged. The treatments applied from April 15 to September 15, starting 1993 for 1994 trees, which treated N June 1994. Net photosynthesis, amount activity Rubisco, N, starch, C:N ratio SLA needles measured during the growing season 1995.Light-saturated net photosynthetic rates 1-year-old current-year shoots at not affected by growth or fertilization. Elevated reduced relative proportion Rubisco soluble proteins trees. also chlorophyll (fresh weight basis) Soluble protein ]. decreased Rubisco:chlorophyll Starch significantly increased only dry structural basis (dry minus starch) resulting an increase ratio. Fertilization had no effect protein, chlorophyll, needles. decrease proportions indicates reallocation resources away nonphotosynthetic processes other plant parts. Acclimation occurred single exposed high ], despite large sink tree. responses elevation similar.