Effects of UV radiation on photosynthesis of Sargassum muticum

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“…Nonetheless, compared to Sargassum muticum, another species of Sargassum genus that have not been observed to form gold tides, the inhibition of UVR on S. horneri was relatively mild. The F v /F m of S. muticum exposed to 2 h UV radiation was more severely reduced (to less than 0.2) (Xu et al, 2023b). UVR radiation mainly damaged water oxidation complexes in the PSII reaction center, where electrons were transferred to P 680 ( Ivanova et al, 2008), leading to the formation of excessive reactive oxygen species (ROS).…”

“…Two radiation treatments were obtained using a solar simulator (Sol 1200, Hönle GmbH, Germany) and two types of filters (Nantong, China), and the emission spectrum of the solar simulator compared with sunlight and transmittance of two types of filter were shown in Figure 1. Thalli that were cultivated under various conditions of N acclimatization were exposed to two radiation treatments, PAR (400-700 nm, 150 W m -2 ) and PAR +UVR (280-700 nm, 150 W m -2 + 28 W m -2 ), for 2 h to simulate the high UVR on the seawater surface in the afternoon (Xu et al, 2023a, Xu et al, 2023b. The irradiance levels were set according to the radiation on the sea surface when the golden tide of S.horneri bloomed (Qi et al, 2017;Xu et al, 2022), and measured by a radiometer (PMA 2100, Solar Light, USA).…”