Table 4.

Repeated measures analysis of variance results for length measures for corn lower- and upper-root systems and the two combined.

Source	df	Lower roots	Upper roots	Lower and upper roots combined
		P-value
Group† (in Week 1)	1	0.3828	N/A‡	0.7720
Group† (in Week 2)	1	0.0180	0.2560	0.1572
Group† (in Week 3)	1	0.1628	0.1307	0.1004
Between-subject effects
Group	1	0.1118	0.1807	0.1233
Error	4
Within-subject effects
Week	2‡	0.0026	0.0007	0.0006
Week × Group	2	0.1718	0.0035	0.0809
Error (Week)	8

^†Except for N/A, the Error df is 4 (df: number of degrees of freedom).

^‡Corn plants of the salt-stressed group had no upper root in Week 1. It follows: (i) the non-relevance of performing a statistical test to compare groups for their upper-root lengths in Week 1; (ii) within-subject effects with 1, 1, and 4 df instead of 2, 2, and 8 df, due to the inclusion of 2 weeks (Weeks 2 and 3) instead of the 3 weeks in the ANOVAR for upper-root length.