Table 1. The statistical significance of the effects of leaf-stage and cultivars on fine-root traits, total phenolic acid contents, inhibition on root length and plant dry weight of lettuce.

Factor	Dependent variable	df	F	P value
Leaf stage	root length (0–0.2 mm)	7	114.670	0.001***
	root length (0.2–2.0 mm)	7	10.996	0.001***
	root surface area	7	14.815	0.001***
	root volume	7	12.646	0.011*
	root tips number	7	1088.983	0.002**
	root biomass	7	59.672	0.000***
	total phenolic acid content	7	11.562	0.002**
	inhibition on root length	7	17.104	0.001***
	inhibition on dry weight	7	7.487	0.002**
Cultivar	root length (0–0.2 mm)	2	18.534	0.014*
	root length (0.2–2.0 mm)	2	1.659	0.048*
	root surface area	2	1.013	0.134
	root volume	2	1.644	0.116
	root tips number	2	135.944	0.040*
	root biomass	2	5.410	0.005**
	total phenolic acid content	2	3.388	0.028*
	inhibition on root length	2	52.911	0.001***
	inhibition on dry weight	2	9.972	0.002**

Notes.

The multivariate analysis with General Linear Model were used (Fixed Factors: leaf stage, cultivar).

^*0.01 < P < 0.05.

^**0.001 < P < 0.01.

^***P < 0.001.