Figure 4 presented the effect of different allelochemical concentrations released from P. stratiotes root exudates on the algae liquid EC value of M. aeruginosa. It showed that in the control group, the algae liquid EC value was consistent with the algae biomass. The EC value decreased as the algae biomass increased, demonstrating that nutrient elements in the culture fluid were absorbed by cells during their growth and propagation. This absorption resulted in the decrease in ion concentrations outside the cell as well as the decrease in the EC value. In the low-concentration P. stratiotes root exudate (0.2 g mL−1) treatment group, the EC value of M. aeruginosa culture liquid was consistent with that of the control group, suggesting that the permeability of the cell membrane was not damaged.