Abstract: Due to the high economic value and market demand of Hizikia fusiformis(Harvey)Okamura(Sargassaceae,Phaeophyta),the aquaculture of this alga is now being considered for larger scale production in China.Complete artificial seedling of Hizikia via sexual reproduction is essential in both conserving the natural resource and further promoting cultivation development for this economic important species.Obtaining a large number of male and female receptacles of Hizikia with identical developmental stage is the prerequisite for increasing the efficiency and effectiveness of artificial seedling.However,the developments of the male and female receptacles of Hizikia are usually not synchronized.In the present work,we tried to research the preservation methods for isolated female receptacles of Hizikia at low and ultra-low temperatures,and explore their application in artificial seedling of Hizikia via sexual reproduction.Mature plants of Hizikia were collected from the low intertidal zone at Yunao Bay,Nanao Island,Shantou,China during June when Hizikia reached the peak of sexual reproduction.The female receptacles were cut from the middle part of the plants and were maintained in seawater with room temperature of about 20 ℃.Firstly the isolated receptacles were pre-treated.The pre-treatments procedures included election of protectants(such as seawater,DMSO,glycerol,sucrose,DMSO+glycerol+sucrose),putting receptacles in submersed or emersed states,and the freezing steps.The receptacles were then preserved at ultra-low temperature(liquid N₂,-196 ℃),freezing temperature(-18 ℃),or low temperature(5 ℃)respectively.We had adopted several indicators,i.e.,the photosynthetic and respiratory activities,relative viability of cells,and the capacity of gamete release,to check the reliability of all kinds of preservation methods.The results showed that the protocols of ultra-low and freezing temperatures preservation were not ideal.However,the photosynthetic and respiratory activities,relative viability of cells,and the capacity of gamete release were nearly maintained after the receptacles were preserved for 30 d at low temperature in emersed state.This supplied a simple and safe approach of receptacles preservation.We discussed the application of receptacles preservation.Low temperature preservation of isolated receptacles of Hizikia can be applied to artificial seedling.Additionally,receptacles of Hizikia can be safely transported to another site for a long time as long as the receptacles are preserved at low temperature.