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首页> 外文期刊>Marine biology >Diurnal variation in chlorophyll fluorescence of Thalassia testudinum seedlings in response to controlled salinity and light conditions
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Diurnal variation in chlorophyll fluorescence of Thalassia testudinum seedlings in response to controlled salinity and light conditions

机译：盐度和光照条件对Tha草幼苗的叶绿素荧光日变化的影响。

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Diurnal variability in chlorophyll fluorescence caused by dynamic irradiance conditions is an important issue when using pulse amplitude modulation fluorometry to measure physiological conditions of plants at the landscape scale. We examined the use of slopes and y-intercepts of diurnal effective photochemical efficiency of photosystem Ⅱ (PSⅡ) (ΔF/F_m') versus photosynthetically active radiation (PAR) regressions in addition to direct measurements of maximum photochemical efficiencies of PSII (F_v/F_m) values to assess physiological status of Thalassia testudinum seedlings in a controlled mesocosm study. Seedlings were exposed to two light treatments (full sun and 50-70 % light reduction) and three salinity treatments (20, 35, and 50). Measurements were taken at 0600,0900, 1200, 1500,1800, and 2100 hours in order to assess the diurnal variation in photochemical efficiency of PSII and PAR, with measurements at 2100 providing F_v/F_m. Results indicated significant effects of light and salinity on regression y-intercepts and measured F_v/F_m values. Shaded seedlings had higher values for both parameters, suggesting low-light acclimation. The highest salinity treatment resulted in significant reductions for both parameters, suggesting stress. Stress was also indicated by significant reductions in both seedling leaf growth and mean differences between seedling leaves and media osmolalities in the hypersaline treatments (152.0 ± 26.4 vs. 630 ± 40.2 mmol kg~(-1) for the control treatments). Slopes of ΔF/F_m' versus PAR significantly differed with varying light treatments, with full sun seedlings exhibiting shallower slopes than shaded seedlings, indicating higher efficiency of dissipation of excess energy (photoprotection). These experimental results confirm field data suggesting that diurnal ΔF/F_m' versus PAR regressions are responsive to changes in the physiological status of T. testudinum and that the y-intercepts of diurnal regressions may be used as a proxy for F_c/F_m.
机译：当使用脉冲幅度调制荧光测量法在景观尺度上测量植物的生理条件时，动态辐照条件引起的叶绿素荧光的日变化是一个重要的问题。除了直接测量PSII的最大光化学效率（F_v / F_m）外，我们还研究了光系统Ⅱ（PSⅡ）的日有效光化学效率（ΔF/ F_m'）与光合有效辐射（PAR）回归的斜率和y截距的使用）值，以在受控的中观宇宙研究中评估地中海蛇舌草幼苗的生理状态。将幼苗暴露于两种光照处理（全日照和50-70％的光照减少）和三种盐度处理（20、35和50）。为了评估PSII和PAR的光化学效率的日变化，在0600,0900、1200、1500、1800和2100小时进行了测量，在2100处提供了F_v / F_m。结果表明光和盐度对回归y轴截距和测得的F_v / F_m值有显着影响。阴影幼苗的两个参数值都较高，表明光线较弱。最高盐度处理导致两个参数的显着降低，表明存在压力。高盐处理中幼苗叶片的生长显着减少，幼苗叶片之间的平均差异和介质渗透压也表明了胁迫（对照处理为152.0±26.4 vs. 630±40.2 mmol kg〜（-1））。 ΔF/ F_m'相对于PAR的斜率在不同的光照处理下有显着差异，日光充足的幼苗比带阴影的幼苗显示出更浅的斜率，表明更高的能量消散效率（光保护）。这些实验结果证实了田间数据，表明昼夜ΔF/ F_m'与PAR的回归对睾丸三叶草生理状态的变化有响应，并且昼夜回归的y截距可以用作F_c / F_m的代理。

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    《Marine biology》 |2013年第3期|591-605|共15页
  • 作者

    Jacqueline F. Howarth; Michael J. Durako;

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    Department of Biology and Marine Biology, Center for Marine Science, The University of North Carolina Wilmington, 5600 Marvin Moss Ln., Wilmington, NC 28409, USA;

    Department of Biology and Marine Biology, Center for Marine Science, The University of North Carolina Wilmington, 5600 Marvin Moss Ln., Wilmington, NC 28409, USA;

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