considerably significantP < 0.001
It was seen that the linear effects of all the factors were significant ( P < 0.001) and the coefficient of X 1 2 , X 2 2 , X 3 2 and X 5 2 were considerably significant ( P < 0.001) in comparison with the interaction terms X 1 X 5 ( P = 0.0299) and X 3 X 4 ( P = 0.0012).