Table 3.

ANOVA based on the quadratic polynomial model for the growth of the endophytic bacterium B. cereus RCL 02

Source	Sum of squares	Degree of freedom	Mean square	F -value	P -value
Model	311.54	14	22.25	10.50	< 0.0001 ***
X 1	48.40	1	48.40	22.84	0.0002 ***
X 2	1.76	1	1.76	0.8322	0.3761
X 3	36.05	1	36.05	17.02	0.0009 ***
X 4	19.51	1	19.51	9.21	0.0084 ***
X 1 X 2	4.84	1	4.84	2.28	0.1515
X 1 X 3	5.76	1	5.76	2.72	0.1200
X 1 X 4	1.56	1	1.56	0.7374	0.4040
X 2 X 3	1.56	1	1.56	0.7374	0.4040
X 2 X 4	0.0025	1	0.0025	0.0012	0.9731
X 3 X 4	9.92	1	9.92	4.68	0.0470 **
$X_1^2$	91.98	1	91.98	43.41	< 0.0001 ***
$X_2^2$	74.67	1	74.67	35.24	< 0.0001 ***
$X_3^2$	66.96	1	66.96	31.60	< 0.0001 ***
$X_4^2$	10.08	1	10.08	4.76	0.0455 **
Residual	31.78	15	2.12
Lack of fit	13.39	10	1.34	0.3639	0.9184
Pure error	18.40	5	3.68
Cor total	343.32	29

(***) – highly significant,

(**) – significant at the 95% probability level;

X₁, X₂, X₃, and X₄ are the four independent variables—molasses, ammonium sulfate, pH, and incubation time, respectively; the lack-of-fit F -value of 0.36 implies the lack of fit is not significant relative to the pure error