Free-air CO2 enrichment of wheat: leaf flavonoid concentration throughout the growth cycle

Although flavonoid concentration was dependent on growthTo test the predictions that plants will have a larger flavonoid concentration in a future world with a CO2-enriched atmo- stage, the effects of treatments on phenology did not invali-sphere, wheat (Triticum aesti7um L. cv. Yecora Rojo) was date the comparisons between treatments. CO2-enriched plants had higher flavonoid concentrations (14 % more isoori-grown in a field experiment using FACE (free-air CO2 enrich-entin, an average of 7.0 mg g1 for ambient CO2 vs anment) technology under two levels of atmospheric CO2 con-centration: ambient (370 mmol mol1) and enriched (550 mmol average of 8.0 mg g1 for enriched CO2), higher TNC mol1), and under two levels of irrigation: well-watered concentrations and lower N concentrations in upper canopy leaves throughout the growth cycle. Well-irrigated plants had(100 % replacement of potential evapotranspiration) and half-higher flavonoid concentrations (11 % more isoorientin, anwatered. We also studied the effects of CO2 on the concentra-average of 7.1 mg g1 for half watered vs an average of 7.9tion of total non-structural carbohydrates (TNC) and nitrogen (N), two parameters hypothesized to be linked to flavonoid mg g1 for well-watered) throughout the growth cycle, metabolism. Throughout the growth cycle the concentration of whereas the effect of irrigation treatments on TNC and N was isoorientin, the most abundant flavonoid, decreased by 62 % more variable. These results are in accordance with the hy-potheses that higher carbon availability promoted by CO2-en-(from an average of 12.5 mg g1 on day of year (DOY) 41 t