Abstract
Light is an important resource for plant growth and development, crops need to change their physiological characteristics to different light environments. Fragaria ananassa Duch. cv. Toyonoka. is an important economic plant which is widely planted at home. A greenhouse experiment was conducted from April 2010 with different sun-shading treatment, 85% (CK), 60% (T<sub>1</sub>), 35% (T<sub>2</sub>) and 10% (T<sub>3</sub>). After 7 days of shading stress, the physiological characteristics were slowly recovered. The results showed that (1) Under shading condition, Light saturation rate (Amax), Apparent Quantum Yield (AQY), Carboxylation Efficiency (CE), dark respiration (Rd), Light Saturation Point (LSP) and Light Compensation Point (LCP) became lower. (2) The maximal fluorescence (Fm), light energy transformation efficiency of PS II (Fv/Fm), actual photochemical efficiency of PS II in the light (Yield), photochemical quenching coefficient (qP) declined with shading stress increase. (3) There were significant difference in the chlorophyll fluorescence parameters among different treatment groups by the end of sun-shading treatment (p<0.05). After the light was recovered, the physiological characteristics could rapidly recover under low shading stress and moderate shading stress, while in severe shading stress the physiological characteristics hardly recover.
Highlights
There is a broad consensus in ecology that light is an important resource for the survival, growth and distribution of crops (Jensen et al, 2012)
After the light was recovered, the physiological characteristics could rapidly recover under low shading stress and moderate shading stress, while in severe shading stress the physiological characteristics hardly recover
When the light intensity is greater than 600 μmol/m2·s, with the increase of light intensity, the photosynthetic rate (Pn) tend to be stable, and the difference between the treatment increase
Summary
There is a broad consensus in ecology that light is an important resource for the survival, growth and distribution of crops (Jensen et al, 2012). In different time and space conditions, the Photosynthetic Photon Flux Density (PPFD) is different, and crops need to develop acclimation and plasticity mechanism to cope with the varying light regimes by changing their morphological and physiological adaptations to different light environments (Gianoli and Valladares, 2012; Wyka et al, 2012). Examples for an active type of plasticity are an increase in specific leaf area (Delagrange, 2011), in leaf size (Valladares and Pearcy, 1998), or the elongation of internodes (Van Kleunen and Fischer, 2005). Crops may change leaf structure and physiology, which determines the leaf carbon acquisition and gas exchange (Gianoli and Valladares, 2012; Wyka et al, 2012)
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