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Water stress induces different levels of photosynthesis and electron transport rate regulation in grapevines
Author(s) -
FLEXAS J.,
ESCALONA J. M.,
MEDRANO H.
Publication year - 1999
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1046/j.1365-3040.1999.00371.x
Subject(s) - photosynthesis , chlorophyll fluorescence , stomatal conductance , transpiration , electron transport chain , photorespiration , chemistry , chlorophyll , horticulture , photochemistry , botany , biology
A , net CO 2 assimilation rate
E , leaf transpiration
ETR , electron transport rate
F s , fluorescence yield at steady state
F m and F m ', maximal fluorescence levels when all PSII reaction centres are closed in dark‐ and light‐acclimated leaves, respectively
F o and F o ', initial fluorescence levels when all PSII reaction centres are closed in dark‐ and light‐acclimated leaves, respectively
F v / F m , efficiency of excitation capture by open PSII in dark‐adapted leaves
ΔF / F m ', actual photochemical efficiency of PSII
g , stomatal conductance
NPQ , non‐photochemical quenching of chlorophyll fluorescence
PPFD , photosynthetic photon flux density
Ψ PD and Ψ MD , leaf water potential at pre‐dawn and midday, respectively
Rl , estimated photorespiration rate
I 1 and I 2 , Irrigation treatments
R, Recovery treatment
D 1 and D 2 , drought treatments
HD 1 and HD 2 , hard drought treatments
Diurnal time courses of chlorophyll fluorescence and gas‐exchange rates were measured in young potted grapevines ( Vitis vinifera L. cv. Tempranillo) subjected to different conditions of water supply under Mediterranean summer conditions. The irrigated plants exhibited typical diurnal patterns for all measured parameters, showing a correspondence between electron transport rate, net CO 2 assimilation and stomatal conductance. Mild decreases in soil‐water availability led to different degrees of down‐regulation of photosynthesis and increased nonphotochemical quenching of chlorophyll fluorescence. A good correspondence between electron transport rate and CO 2 assimilation was still maintained, suggesting a coregulation of both photosynthetic processes. In contrast, a severe water deficit induced a drastic down‐regulation of photosynthesis and breakage of the above‐mentioned link. Both midday net CO 2 assimilation and electron transport rate significantly correlated with pre‐dawn water potential ( Ψ PD ) ( r 2 = 0·65 and r 2 = 0·92, P < 0·001, respectively). However, when field data were analysed, the relationship between electron transport rate and Ψ PD was not maintained, although net CO 2 assimilation was similarly correlated with Ψ PD . Interestingly, the steady‐state chlorophyll fluorescence yield was a good indicator of plant water stress.