Influence of desiccation and cold preservation on the survive and growth of Porphyra haitanensis and unwanted-alga

The manual cultured Porphyra haitanensis thallus and five large scale unwanted-alga which have growth competitive relations with P.haitanensis thallus:Enteromorphaintestinalis,E.clathrata,Ulva pertusa,Gracilaria asiatica and Ectocarp us confervoides,together with the samples of Cocconeis spp.,were tested by means of desiccation and cold preservation.The results indicated that when it was cultured directly after being desiccated to the water content of 10%~15%,the survival rate of the P.haitanensis thallus was over 99%,showing no significant difference from those without desiccation,where as all the large scale unwanted-alga would die if the water content was below 25% after desiccation.When the water content of the P.haitanensis thallus was 10%,culture them after being stored at a low temperature of 20 for 30 days,then the survival rate would reach up to 99%~100%.If the water ratio was below 10%,then the survival rate would belower than 30%,and death even occurred.When the P.haitanensis thallus was stored with the water content ratio higher or lower than 10%~15% under low temperature,both its survival rate and the rate of weight gain when cultured after cold preservation would get aff ected.However,cold preser vation duration would bring a 100% death rate to the large scale unwanted-alga.Therefore,the ways of desiccation and cold preservation could effectively kill the unwanted-algas that have competitive relations with P.haitanensis thallus,which could be applied to raising the yield of P.haitanensis in practice.