Table 1.

ANOVA results for root morphological traits as affected by root type (RT), root age (RA), P supply treatment (P), and their interactions

	RP	RB	APase	RL	SA	RV	SRL	SRSA	RTD
F
RT	71.09	22.23	0.01	271.18	21.43	57.95	165.21	28.01	149.49
RA	24.81	54.69	46.29	8.63	72.37	37.73	17.65	54.52	1.40
P	2.95	4.29	6.02	3.36	3.95	1.73	0.13	0.53	2.50
RT×RA	97.78	38.77	132.45	0.04	111.45	148.01	137.69	35.71	12.07
RT×P	1.13	3.69	0.40	8.30	0.48	1.86	0.49	0.75	0.32
RA×P	0.78	6.13	0.22	0.27	0.81	0.63	0.88	13.02	2.52
RT×RA×P	28.92	93.04	7.40	1.30	5.70	15.13	15.47	0.07	8.02
P
RT	< 0.001	< 0.001	0.935	< 0.001	< 0.001	< 0.001	< 0.001	< 0.001	< 0.001
RA	< 0.001	< 0.001	< 0.001	0.004	< 0.001	< 0.001	< 0.001	< 0.001	0.239
P	0.037	0.007	0.001	0.022	0.011	0.167	0.945	0.664	0.064
RT×RA	< 0.001	< 0.001	< 0.001	0.842	< 0.001	< 0.001	< 0.001	< 0.001	0.001
RT×P	0.34	0.015	0.750	< 0.001	0.695	0.143	0.689	0.526	0.831
RA×P	0.51	0.001	0.884	0.850	0.492	0.597	0.454	< 0.001	0.063
RT×RA×P	< 0.001	< 0.001	< 0.001	0.280	0.001	< 0.001	< 0.001	0.976	< 0.001

Note: DF_RT= 1, DF_RA =1, DF_P =3, DF_RT×RA = 1, DF_RT×P = 3, DF_RA×P = 3, DF_RT×RA×P=3. RP, root phosphorus (g kg^–1); RB, root biomass (g plant^–1); APase, root APase (µmol pNP g^− 1 min^− 1); RL, root length (cm); SRL, specific root length (cm mg^–1); SA, root surface area (cm²); SRSA, specific root surface area (cm² mg^–1); RV, root volume (cm³); RTD, root tissue density (mg cm^–3)