The permeability of the membrane is affected by cell membrane damage, becoming increased when the cell membrane is damaged. The electrolyte exosmoses from the cell would result in the increase of EC outside the cell (Allen 1995; Zhang et al. 2010). Li et al. (2007) demonstrated that the reed allelochemical EMA caused disruption of the algae cell membrane in Chlorella pyrenoidosa and M. aeruginosa, K+ and Ca2+ were discharged from inside the cell. Hence, the change of EC value in the algae liquid reflected the change in membrane permeability.