Table 6.

The effect of different qualities of light and three methods of replacement of nutrient solution on DPPH radical scavenging activity and enzymes activity of two varieties of lettuce in floating hydroponics.

Source of variation	Df	DPPH radical scavenging activity	Guaiacol peroxidase enzyme activity	Catalase enzyme activity	Superoxide dismutase enzyme activity
Variety (V)	1	0.0001ns	2234**	8.69*	534**
Light (L)	3	176**	24,004**	275**	10,162**
Nutrient solution (N)	2	26.5**	2361**	27.09**	118ns
V*L	3	194**	6937**	63.9**	1990**
V*N	2	142**	20,389**	154**	7233**
L*N	6	183**	18,891**	255**	11,573**
V*L*N	6	82.2**	9500**	135**	2339**
Experimental Error	48	1.91	80.2	1.46	52.8
Coefficient Variance (%)	–	3.28	3.28	4.0	3.06

ns, * and ** indicate non-significance, significant at 5% and 1% probability level (Duncan’s Test), respectively.