Abstract:In order to investigate the response of growth and PSⅡ of Dunaliella salina to different nitrogen sources, we performed experiments by using NaNO3, CO(NH2)2, NaNO2, and NH4Cl as nitrogen sources and N control was set in this study. Our results showed that: (1) D. salina grew faster under CO(NH2)2 with a maximum growth rate[μmax, (0.482±0.032)/d] per day than under other nitrogen sources. (2) Results of chlorophyll fluorescence indicated no significantly different in the initial slope of the RLC before the onset of saturation (α), the maximum potential ETR (rETRmax), the maximum photochemistry efficiency (Fv/Fm), the maximum quantum yield of primary photochemistry (φP0), quantum yield for electron transport (φE0), probability(t=0) that a trapped exit on moves an electron into the electron transport chain beyond QA- (ψ0), absorption flux per RC (ABS/RC) and trapped energy flux per RC(t=0) (TR0/RC) among NaNO3, CO(NH2)2, and NaNO2 groups (P>0.05), while there is significantly different in these parameters when compared with NH4Cl and N controls (P<0.05). (3) Compared with the NaNO2, NaNO3, and CO(NH2)2 groups, the relative variable fluorescence (Vj) of D. salina increased significantly under nitrogen free treatment (P<0.05), which suggesting restriction of photosynthetic electron transport of D. salina from QA- to QB and accumulation of QA-. However, we can infer destroy of the oxygen evolving complex (OEC) of D. salina by the NH4Cl from the appearance of K phase under NH4Cl. As a whole, these results showed that D. salina grew much faster under CO(NH2)2 than that under NaNO3 and NaNO2, whereas the growth of D. salina was inhibited significantly by nitrogen deficiency, and the number of reactive centers in PS II was decreased, and the electron transport was blocked. However, toxicity effect of NH4Cl on D. salina caused its death in a short time and the OEC of D. salina was damaged.