Table 3.

Factor coefficients estimated after analysis of Doehlert design and their corresponding R² and A_F.

Factors	Coeff.	Julius		Ponticus
		Proteins conc. (mg/mL)	IAA (%)	Proteins conc. (mg/mL)	IAA (%)
Constants
	b0	0.472	71.5	0.406	60.6
Linear
X 10	b1	−0.071 **	−1.0	−0.212 ***	−13.8 ***
X 6	b2	0.086 **	−1.7	−0.115 *	5.1 **
X 8	b3	0.102 ***	−1.4	−0.149 **	−14.6 ***
Quadratic
X10* X10	b11	0.023	11.4**	0.089	−0.2
X6* X6	b22	−0.047	11.5**	0.156 *	−14.4
X8* X8	b33	0.098 **	7.1*	0.112	−0.8
Interaction
X10* X6	b12	−0.017	−1.6	−0.208 *	−2.0
X10* X8	b13	0.031	−6.7	0.049	−8.8 *
X6* X8	b23	−0.039	3.6	0.356 **	−1.1
R2		0.94	0.91	0.93	0.98
AF		1.05	1.02	1.08	1.03

* Significant at p ≤ 0.05, ** significant at p ≤ 0.01, *** significant at p ≤ 0.001. X₆ is extraction time, X₈ the pH and X₁₀ sodium chloride concentrations. A_F is the accuracy factor.