Table IV.

Results of regression analysis of Plackett-Burman design.

Source	Factor	df	Sporulation (Y)
			Sum of squares	Mean square	F-value	p-value
Model		5	11.69	2.34	7.84	0.0060**
X1	0.7365	1	6.51	6.51	21.81	0.0016**
X2	0.0313	1	0.0117	0.0117	0.0393	0.8477
X4	-0.4789	1	2.75	2.75	9.22	0.0162*
X5	0.0448	1	0.0241	0.0241	0.0807	0.7836
X7	-0.4468	1	2.40	2.40	8.03	0.0220*
Residual		8	2.39	0.2985
Cor total		14	15.30

^*indicates significant (p < 0.05)

^**indicates very significant (p < 0.001)