阳光紫外辐射对室内水培发状念珠藻生理特性的影响

发状念珠藻（Nostoc flagelliforme Bornet & Flahault）是一种重要的陆生经济蓝藻，室内培育出的原植体如何适应阳光辐射的问题尚需探讨。为此，作者将室内水培发菜置于阳光下培养，测定了其生长、有效光化学效率（F/Fm΄）和色素的变化。结果表明，较高的可见光（PAR，395－700 nm）和紫外辐射（UVR，280－395 nm）均导致水培发菜的F/Fm΄下降。第1天中午，PAR和UVR分别使F/Fm΄下降了54％和13％；傍晚，F/Fm΄有部分恢复。UVR对发菜适应阳光2d后的生长无负面作用。发菜在适应全阳光辐射期间，紫外吸收物质（Scytonemin和Mycosporine-like amino acids）含量不断增加，9d后，分别增加了124倍和9倍。这些紫外吸收物质的增加对发菜细胞降低光抑制，适应阳光辐射，起到了重要作用。本研究的结果可为水培发菜室外培养方法的建立提供一定的理论依据。

Effects of solar ultraviolet radiation on physiological characteristics of the aquatic-living colonies of Nostoc flagelliforme cultured indoor

Nostoc flagelliforme Bornet & Flahault, named popularly as 'Facai' in Chinese, is a terrestrial cyanobacterium of great economic value. Although aquatic-living colonies were developed under indoor conditions, little is known whether they could and how they would adapt to solar radiation. Therefore, we exposed the colonies to different solar radiation treat-ments, photosynthetically active radiation (P:PAR,395-700 nm), PAR + ultraviolet radiation-A ( PA ,320-700 nm) or PAR + total ultraviolet radiation (PAB,280-700 nm). Changes of their growth, effective quantum efficiency (△F/F'm) and pigments were estimated during the experimental period. It was found that high levels of both PAR and ultraviolet radiation (UVR,280-395 nm) reduced the △F/F'm of the colonies. △F/F'm was reduced about 54% by PAR and further declined 13% by UVR. The △F/F'm recovered in the late afternoon. After two days' acclimation to solar radiation, the biomass of the colonies increased during the following days. UV-absorbing compounds, scytonemin and mycosporine-like amino acids (MAAs), increased by 124 and 9 times, respec-tively, in 9 days. Such increased UV-absorbing substances played an important role in protecting the aquatic-living colo-nies of Nostoc flagelliforme from solar UVR. The results may be useful for the mass production of the aquatic-living colo-nies of Nostoc flagelliforme under outdoor conditions.