Laboratory one-time culturing method was used to study the interaction of the ratios of organic nitrogen and light intensity on the growth and photosynthesis of the brown tide Phaeocystis globosa. The results showed that the changes of organic nitrogen content has significantly influenced on the growth of P·globosa. In the high-light conditions ( 120 μmol·m-2·s-1 ) , control and experimental groups all grow well. When the organic nitrogen content of 20％, the cell density, specific growth rate were significantly higher than the control and other treatments. P·globosa grows best of all. In low-light conditions( 10 μmol·m-2·s-1 ), when the organic nitrogen content more than 50％, the cell density is higher than the nitrate and organic nitrogen is 20％ of the experimental group. Either high-light or low- light conditions, the ratios of organic nitrogen has no significantly influenced on maximal photochemical efficiency (Fv/Fm) of P.globosa.but in the high-light, different nitrogen sources has significantly influenced on maximal photochemical efficiency. Nitrate group higher than Urea. while In low-light conditions, when urea was provided as sole nitrogen substrates, P. globosa exhibited the maximum photochemical efficiency 0.752, but no significant difference compare withnitrate. As to the marine microalgae which can use inorganic nitrogen and dissolved organic nitrogen, The presence of organic nitrogen could significantly promote their proliferation, leading to the changes of phytoplankton community composition and could triggering globosa bloom in appropriate environmental conditions.%采用实验室一次性培养的方法,研究了有机氮比率和光照强度相互作用对赤潮藻球形棕囊藻(Phaeocystisglobosa)生长和光合作用的影响.结果表明,在高光条件下(120 μm01.m-2.s-1),有机氮含量为20%时,其细胞密度、比生长率均显著高于对照组和其他处理组,球形棕囊藻生长最好;在低光条件下(10μμm01.m-2.s-1),有机氮含量大于50%时,其细胞密度要高于硝态氮和有机氮为20%的实验组.无论是高光还是低光条件下,有机氮含量变化对球形棕囊藻Fv/Fm影响不大.但在高光条件下,不同氮源对其Fv/Frm有显著的影响,硝氮组显著高于尿素组而在低光照条件下,以尿素为唯一氮源的对照组达到最大光能转化效率0.752,但与硝氮组差别不显著.对于既能利用无机氮又能利用有机氮的海洋微藻来说,有机氮的存在可能显著促进其增殖,从而改变浮游植物群落结构,并可能在适宜的环境条件下形成赤潮.
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