Guangxi Zhiwu (Mar 2024)
Plasticity of Phoebe bournei seedlings adapting to low light environment
Abstract
The purpose of this study is to explore the survival strategy of Phoebe bournei seedlings in natural communities under extremely low light environment. Two-year-old seedlings of P. bournei were used as experimental materials. Leaf morphology, anatomical structure and photosynthetic physiological characteristics of P. bournei seedlings were measured by simulating different light environments (100%, 35% and 10% light transmittance), and to explore the internal relationship between seedling morphology, physiological plasticity and light adaptation. The results were as follows: (1) The leaf length, leaf width, leaf area and specific leaf area (SLA) of seedlings increased with the decrease of light intensity. The leaf thickness, palisade tissue thickness, spongy tissue thickness and palisade/spongy (palisade tissue thickness/spongy tissue thickness) of 10% light transmittance were the minimum. (2) The net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), light utilization efficiency (LUE), photochemical quenching coefficient (qp), non photochemical quenching coefficient (NPQ), effective photosynthetic quantum yield (Fv′/Fm′) and potential photochemical efficiency (Fv/Fo) of photosystem Ⅱ of 35% light transmittance were significantly higher than those of 100% and 10% light transmittances. (3) Chlorophyll a, chlorophyll b, carotenoids, total chlorophyll and maximal photochemical efficiency (Fv/Fm) all increased with the decrease of light intensity, but chlorophyll a/b decreased with the decrease of light intensity. (4) The phenotypic plasticity indexes of seedling structure and physiology showed that photosynthetic pigment content characteristics > morphological characteristics > photosynthetic characteristics > anatomical structure characteristics > chlorophyll fluorescence parameter characteristics, among which, the phenotypic plasticity indexes of leaf area, SLA, Pn, Gs, LUE and photosynthetic pigment content ranged from 0.455 to 0.755. To sum up, P. bournei seedlings are not suitable to grow under full light, and perform well under about 35% light transmittance; under extremely low light with 10% light transmittance, P. bournei leaves can improve light energy capture by increasing leaf area, SLA, Pn and photosynthetic pigment content; the seedlings of P. bournei mainly adapt to the low light environment by adjusting the plasticity of photosynthetic pigment content and morphology, coordinating with the changes of anatomical structure, photosynthetic physiology and chlorophyll fluorescence parameter plasticity. This study can provide theoretical reference for the management and selection of light environment of P. bournei for future cultivation.
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