Flavonoid responses in wheat grown at elevated CO2: green versus senescentleaves

We compared flavonoids in green, mature, and senescing flag leaves of wheat grown under ambient (AC - 370 mu mol mol(-1)) and elevated (EC - 550 mu mo l mol(-1)) concentrations of CO2 in a FACE (Free Air CO2 Enrichment) system . The concentrations of flag leaf flavonoids (e.g., isoorientin and tricin) decreased to one third in mature leaves, and the majoritary isoorientin al most disappeared in senescing leaves. Flavonoid concentrations increased in green well-developed flag leaves under EC (46 % isoorientin and 55 % trici n),whereas the differences disappeared in mature and senescing flag leaves. Predictions of changes in litter phenolic concentrations and their effects on decomposition rates under EC based on changes in green leaves need to b e revised.