Effect of CO2 enrichment on non-structural carbohydrates in leaves, stems and ears of spring wheat

Field-grown spring wheat (Triticum aestivum L, cv, Dragon) was exposed to a mbient and elevated CO2 concentrations (15 and 2 times ambient) in open-top chambers. Contents of non-structural carbohydrates mere analysed enzymatic ally in leaves, stems and ears six times during the growing season. The imp act of elevated CO2 on wheat carbohydrates was non-significant in most harv ests. However, differences in the carbohydrate contents due to elevated CO2 were found in all plant compartments. Before anthesis, at growth stage (GS ) 30 (the stem is 1 cm to the shoot apex), the plants grown in elevated CO2 contained significantly more mater soluble carbohydrates (WSC), fructans, starch and total non-structural carbohydrates (TNC) in the leaves in compar ison with the plants groan in ambient CO2. It is hypothesised that the plan ts from the treatments with elevated CO2 were sink-limited at GS30, After a nthesis, the leaf WSC and TNC contents of the plants from elevated CO2 star ted to decline earlier than those of the plants from ambient CO2. This may indicate that the leaves of plants grown in the chambers with elevated CO2 senesced earlier. Elevated CO2 accelerated grain development: 2 weeks after anthesis, the plants groan in elevated CO2 contained significantly more st arch and significantly less fructans in the ears compared to the plants gro wn in ambient CO2. Elevated CO2 had no effect on ear starch and TNC content s at the final harvest. Increasing the CO2 concentration from 360 to 520 mu mol mol(-1) had a larger effect on wheat nonstructural carbohydrates than the further increase from 520 to 680 mu mol mol(-1). The results are discus sed in relation to the effects of elevated CO2 on yield and yield component s.