Articles
RESPONSE OF RHAMNUS ALATERNUS TO FIVE SHADING LEVELS
Article number
927_11
Pages
109 – 114
Language
English
Abstract
Light management is a key factor in the successful production of nursery plants.
To produce autochthonous species in nurseries in a competitive way (both from a financial and esthetic point of view), it is important to know their cultural requirements. Rhamnus alaternus is a promising autochthonous evergreen Mediterranean shrub with bright green leaves and small red fruits, which is well adapted to pruning and pot growth.
However, its response to light has not been studied.
In this study, therefore, we submitted R. alaternus to five light levels for a year: a control (without shading net) and four shading percentages obtained by using nets (25, 50, 65 and 80% of shade). At the end of the year, leaf soluble sugar, leaf layer cell thickness, leaf area, leaf stomatal density and pore dimensions and chlorophyll fluorescence were determined.
Leaf soluble sugars were reduced by 40% in the 65 and 80% shading treatments.
Leaf thickness was reduced in all the shading treatments compared with the control, while specific leaf area (SLA) increased.
Stomatal density and pore area were reduced at shading percentages ≥65%, as were photosystem II (PSII) efficiency and photochemical quenching (qP); however, non-photochemical quenching (NPQ) increased.
The highest level of shade (80%) produced irreversible damage in PSII as a result of reduced dark adapted PSII efficiency (Fv/Fm). So, R. alaternus leaves are clearly affected by shade and activate adaptation mechanism to improve their light capture capacity; however, shading nets ≥65% are not recommended because of their effect on photochemical activity and soluble sugars.
To produce autochthonous species in nurseries in a competitive way (both from a financial and esthetic point of view), it is important to know their cultural requirements. Rhamnus alaternus is a promising autochthonous evergreen Mediterranean shrub with bright green leaves and small red fruits, which is well adapted to pruning and pot growth.
However, its response to light has not been studied.
In this study, therefore, we submitted R. alaternus to five light levels for a year: a control (without shading net) and four shading percentages obtained by using nets (25, 50, 65 and 80% of shade). At the end of the year, leaf soluble sugar, leaf layer cell thickness, leaf area, leaf stomatal density and pore dimensions and chlorophyll fluorescence were determined.
Leaf soluble sugars were reduced by 40% in the 65 and 80% shading treatments.
Leaf thickness was reduced in all the shading treatments compared with the control, while specific leaf area (SLA) increased.
Stomatal density and pore area were reduced at shading percentages ≥65%, as were photosystem II (PSII) efficiency and photochemical quenching (qP); however, non-photochemical quenching (NPQ) increased.
The highest level of shade (80%) produced irreversible damage in PSII as a result of reduced dark adapted PSII efficiency (Fv/Fm). So, R. alaternus leaves are clearly affected by shade and activate adaptation mechanism to improve their light capture capacity; however, shading nets ≥65% are not recommended because of their effect on photochemical activity and soluble sugars.
Authors
J. Miralles, R. Espín, S. Bañón, J.J. Martínez-Sánchez
Keywords
shade, soluble sugars, chlorophyll fluorescence, leaf morphology
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