Table 5. The regression of the logistic model under different nitrogen sources.

Population growth parameters	Growth equation	Carrying capacity K (×104 cells mL-1)	r (d-1)	Tp (d)	R2
No N	N = 7.23/(1+e(2.321–0.727t))	7.23	0.727	3.2	0.906
N-NO3-	N = 14.89/(1+e(1.941–0.453t))	14.89	0.453*	4.3	0.992
N-NO2-	N = 13.93/(1+e(1.964–0.370t))	13.93	0.370*	5.3	0.925
N-NH4+	N = 16.21/(1+e(2.052–0.515t))	16.21	0.515	4.0	0.978
N-urea	N = 13.35/(1+e(1.612–0.216t))	13.35	0.216*	7.6	0.937

^* indicated there was a statically significant difference between this treatment and the corresponding control group (P<0.05).