Partitioning of photosynthetic electron flow between CO2 assimilation and O2 reduction in sunflower plants under water deficit

Title:

Partitioning of photosynthetic electron flow between CO2 assimilation and O2 reduction in sunflower plants under water deficit

Creator:

Tezara, W., Driscoll, S., and Lawlor, D. W.

Identifier:

https://cdk.lib.cas.cz/client/handle/uuid:d3c8ae1f-e40c-4cef-af25-6d8854a80975
uuid:d3c8ae1f-e40c-4cef-af25-6d8854a80975
issn:0300-3604
doi:10.1007/s11099-008-0020-1

Subject:

chlorophyll fluorescence, electron transport, fluorescence quenching, Helianthus annuus, intercellular CO2 concentration, net photosynthetic rate, and stomatal conductance

Type:

model:article and TEXT

Format:

bez média and svazek

Description:

In sunflower (Helianthus annuus L.) grown under controlled conditions and subjected to drought by withholding watering, net photosynthetic rate (PN) and stomatal conductance (gs) of attached leaves decreased as leaf water potential (Ψw) declined from -0.3 to -2.9 MPa. Although gs decreased over the whole range of Ψw, nearly constant values in the intercellular CO2 concentrations (Ci) were observed as Ψw decreased to -1.8 MPa, but Ci increased as Ψw decreased further. Relative quantum yield, photochemical quenching, and the apparent quantum yield of photosynthesis decreased with water deficit, whereas non-photochemical quenching (qNP) increased progressively. A highly significant negative relationship between qNP and ATP content was observed. Water deficit did not alter the pyridine nucleotide concentration but decreased ATP content suggesting metabolic impairment. At a photon flux density of 550 µmol m-2 s-1, the allocation of electrons from photosystem (PS) 2 to O2 reduction was increased by 51 %, while the allocation to CO2 assimilation was diminished by 32 %, as Ψw declined from -0.3 to -2.9 MPa. A significant linear relationship between mean PN and the rate of total linear electron transport was observed in well watered plants, the correlation becoming curvilinear when water deficit increased. The maximum quantum yield of PS2 was not affected by water deficit, whereas qP declined only at very severe stress and the excess photon energy was dissipated by increasing qNP indicating that a greater proportion of the energy was thermally dissipated. This accounted for the apparent down-regulation of PS2 and supported the protective role of qNP against photoinhibition in sunflower. and W. Tezara, S. Driscoll, D. W. Lawlor.

Language:

Multiple languages

Rights:

http://creativecommons.org/licenses/by-nc-sa/4.0/
policy:public

Coverage:

127-134

Source:

Photosynthetica | 2008 Volume:46 | Number:1

Harvested from:

CDK

Metadata only:

false