Study On Photoperiodic Effect Of Tetraselmis Tetrathele And Prorocentrum Donghaiense

In this paper, the marine micro-algae Tetraselmis tetrathele and Prorocentrum donghaiense were used as experimental material in order to study the photoperiod effect of them. We hope to find whether they have the Photoperiodic response and we want to know the difference of Photoperiodic response between these two kinds of algae if they have. There were 2 man-made groups (A and B) experiments by the length of different photoperiod. Group A included 7 treatments of photoperiod designed not longer than 12h (1h, 2h, 4h, 6h, 8h, 10h and 12h). Group B also included 7 treatments of photoperiod designed not less than 12h (12h, 14h, 16h, 18h, 20h, 22h and 23h). Cells density, biomass, content of chlorophyll-a, intracellular protein and dissolved carbohydrate of all these two kinds of algae were determined. The result showed: (1) T. tetrathele and P. donghaiense all have obvious Photoperiodic effect. There are obvious differences between these two kinds of algae. The growth curve of T. tetrathele presented approximate normal contribution corresponding to the change of photoperiod and there was positive relationship between the growth of P. donghaiense and the change of photoperiod. (2) The adaptive range of these two kinds of algae are quite broad. The cells' index of T. tetrathele, such as cells density, biomass and content of chlorophyll-a, all are high in the Photoperiodic range of 6h-18h. P. donghaiense grows better as the photoperiod prolongs longer. (3) The growth of two kinds of algae all presented optimum range, suboptimum range and unsuitable range of photoperiod. P. donghaiense's suboptimum photoperiod range is 8h-18h, algae's unsuitable photoperiod range is shorter than 6h and optimum photoperiod rangeis longer than 20h. The photoperiod is T. tetrathele's unsuitable range when is shorter than 4h or longer than 20h. T. tetrathele's optimum photoperiod range is 8h-18h and suboptimum photoperiod range is 6h-8h. (4) As to I tetrathele, it is appropriate to use the photoperiod of about 10h in massive production. In the area of marine or sea, which it's long day or sunny, it ought to avoid the break out of P. donghaiense harmful algal blooms.