Details

Autor(en) / Beteiligte

• Cousins, A. B.
• Adam, N. R.
• Wall, G. W.
• Kimball, B. A.
• Pinter, P. J.
• Ottman, M. J.
• Leavitt, S. W.
• Webber, A. N.

Titel

Photosystem II energy use,non‐photochemical quenching and the xanthophyll cycle in Sorghumbicolor grown under drought and free‐air CO 2 enrichment(FACE) conditions

Ist Teil von

• Plant, cell and environment, 2002-11, Vol.25 (11), p.1551-1559

Erscheinungsjahr

2002

Quelle

Access via Wiley Online Library

Beschreibungen/Notizen

• Abstract The present study was carried out to test the hypothesis thatelevated atmospheric CO 2 (Ca) will alleviate over‐excitationof the C 4 photosynthetic apparatus and decrease non‐photochemicalquenching (NPQ) during periods of limited water availability. Chlorophyll a fluorescencewas monitored in Sorghum bicolor plants grown under a free‐aircarbon‐dioxide enrichment (FACE) by water‐stress (Dry) experiment.Under Dry conditions elevated Ca increased the quantum yield ofphotosystem II ( φ PSII) throughout the day throughincreases in both photochemical quenching coefficient ( q p )and the efficiency with which absorbed quanta are transferred toopen PSII reaction centres ( F v ′/ F m ′).However, in the well‐watered plants (Wets) FACE enhanced φ PSIIonly at midday and was entirely attributed to changes in F v ′/ F m ′ . Underfield conditions, decreases in φ PSII under Dry treatmentsand ambient Ca corresponded to increases in NPQ but the de‐epoxidation stateof the xanthophyll pool (DPS) showed no effects. Water‐stress didnot lead to long‐term damage to the photosynthetic apparatus asindicated by φ PSII and carbon assimilation measuredafter removal of stress conditions. We conclude that elevated Caenhances photochemical light energy usage in C 4 photosynthesisduring drought and/or midday conditions. Additionally,NPQ protects against photo‐inhibition and photodamage. However,NPQ and the xanthophyll cycle were affected differently by elevatedCa and water‐stress.