Articles
PHOTOSYSTEM II ACTIVITY IN DROUGHT AND HIGH LIGHT CONDITIONS OF CASTANEA SATIVA MILL. SAPLINGS
Article number
1043_25
Pages
191 – 198
Language
English
Abstract
The objective of this study is to analyze the sensitivity of PS II of Castanea sativa Mill. to drought stress and high light levels by the chlorophyll fluorescence technique.
The increasing of PAR results in reduction of the actual photochemical efficiency (ΔF/Fm) of the water stressed saplings and the controls.
The electron flux is limited in lowest levels of Predawn leaf water potential (Ψpd) probably due to stomatal closure and/or to the inhibition of the dark reactions.
This is a possible mechanism to plant protection of dissipating excess of photochemical energy non utilized in water stressed saplings.
A photoinhibition-induced decline in the rate of photosynthesis at limiting radiation level results from induction of protective mechanisms.
No any changes of Fo, with very low values of the Predawn leaf water potential (Ψpd) and any perturbations of the photosynthetic apparatus of Castanea sativa Mill. saplings are observed.
The decline in PSII efficiency is regulatory, serving a photoprotective role.
Increased levels of energy dissipation which decrease of PSII efficiency may help to protect the PSII from photodamages.
This conclusion was confirmed with the behavior of PSII of the re-watered plants.
Avoidance of permanent photodamages is probably an important component of water stress tolerance strategy of Castanea sativa Mill.
The increasing of PAR results in reduction of the actual photochemical efficiency (ΔF/Fm) of the water stressed saplings and the controls.
The electron flux is limited in lowest levels of Predawn leaf water potential (Ψpd) probably due to stomatal closure and/or to the inhibition of the dark reactions.
This is a possible mechanism to plant protection of dissipating excess of photochemical energy non utilized in water stressed saplings.
A photoinhibition-induced decline in the rate of photosynthesis at limiting radiation level results from induction of protective mechanisms.
No any changes of Fo, with very low values of the Predawn leaf water potential (Ψpd) and any perturbations of the photosynthetic apparatus of Castanea sativa Mill. saplings are observed.
The decline in PSII efficiency is regulatory, serving a photoprotective role.
Increased levels of energy dissipation which decrease of PSII efficiency may help to protect the PSII from photodamages.
This conclusion was confirmed with the behavior of PSII of the re-watered plants.
Avoidance of permanent photodamages is probably an important component of water stress tolerance strategy of Castanea sativa Mill.
Publication
Authors
S. Bratanova-Doncheva
Keywords
sweet chestnut, chlorophyll fluorescence technique, drought, high light, PSII activity, photodamages, water stress tolerance
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