highly significantP < 0.0001
+ 0.0817 X 2 X 4 + 0.0405 X 2 X 5 - 0.0402 X 2 X 6 - 0.2873 X 3 X 4 - 0.1011 X 3 X 5 - 0.1967 X 3 X 6 - 0.0283 X 4 X 5 + 0.2186 X 4 X 6 - 0.0289 X 5 X 6 - 0.769 X 1 2 - 0.2811 X 2 2 - 1.64 X 3 2 - 1.13 X 4 2 - 0.2342 X 5 2 - 0.0627 X 6 2 # The ANOVA results ( Table 2 ) indicated that the model was highly significant ( F = 16.76, P < 0.0001) with a non-significant lack of fit ( P = 0.2443), confirming model adequacy.