Effects of Mn~(2+) on Growth of Scenedesmus quadricauda and Uptake of Ca~(2+) and Mg~(2+)

Mn is one of the essential trace elements for algae growth and functions in many physiological aspects in algae cell.However,the ammention to effects of Mn on the growth of Scenedesmus quadricauda and on other nutrient cation uptake were rarely given by us.In this experiment we observed the effect of Mn2+concentration on the growth and Ca2+,Mg2+uptake of Scenedesmus quadricauda in laboratory.Series of 250 mL flasks containing the prepared Scenedesmus quadricauda culture were incubated at 25℃ for 1 month under different Mn2+concentrations(0,10,100,1 000,10 000,30 000 nmol/L).After that the biomass,chlorophyll a content,the congcentration of Ca2+and Mg2+in culture medium were determined.The results showed all the index were significantly influenced by Mn2+,among which the effect of chlorophyll a content was extremely significant.Lower Mn2+concentrations in culture medium(0～1000 nmol/L)promoted the growth of Scenedesmus quadricauda and synthesis of chlorophyll a,and higher Mn2+concentration would suppress its growth,resulting in a lower biomass and a lower chlorophyll a concentration in cells.With increase of biomass of Scenedesmus quadricauda more Ca2+and Mg2+in medium had been adsorbed by them.In range of Mn2+concentration adopted in this experiment there was no antagonism between uptake of Mn2+and Ca2+、Mg2+.