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Title: FLAVONOID RESPONSES IN WHEAT GROWN AT ELEVATED CO2: GREEN VERSUS SENESCENT LEAVES

Author
item PENUELAS, M - CREAF BARCELONA SPAIN
item ESTIARTE, M - CREAF BARCELONA SPAIN
item Kimball, Bruce

Submitted to: Photosynthetica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/1999
Publication Date: N/A
Citation: Penuelas, M., Estiarte, M., Kimball, B.A. 1999. Flavonoid responses in wheat grown at elevated co2: green versus senescent leaves. Photosynthetica 37(4):615-619.

Interpretive Summary: The CO2 concentration of the atmosphere is increasing and is expected to double sometime during the next century. Such an increase in CO2 is expected to stimulate the growth of plants, and it may also affect the production of various other carbon-based compounds within the plants. In this case, the effects on flavonoids were determined. Flavonoids which are bad-tasting secondary compounds plants make to defend themselves from herbivores and which could also retard the rates of decomposition of plant litter and thereby increase soil carbon storage. We found that elevated CO2 increased the flavonoid concentrations somewhat in green wheat leaves (which should improve wheat's resistance to insects), but not in brown senescent leaves (which means decomposition rates and soil carbon storage should be unaffected). Information such as this is needed to help predict the consequences of the future high CO2 concentrations on agricultural productivity and on soil carbon storage, which should help all consumers of food and fiber.

Technical Abstract: We compared flavonoids in green, mature, and senescing flag leaves of wheat grown under ambient (AC - 370 umol mol-1) and elevated (EC - 550 umol 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 majority of isoorientin almost disappeared in senescing leaves. Flavonoid concentrations increased in green well-developed flag leaves under EC (46% isoorientin and 55% tricin), 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 changes in green leaves need to be revised.