Table I. Allometric analysis comparing shoot biomass and root phenes in the greenhouse at 46 DAP and in the field at 49 DAP.

Root phenes include TCSA (mm²), metaxylem vessel area (MXA; mm²), metaxylem vessel number (MXN), axial hydraulic conductance (Cond.; kg m⁻¹ MPa⁻¹ s⁻¹), basal root length measured in the greenhouse (BRL; cm)/root length density (RLD; cm cm⁻³), basal root whorl number (BRWN), basal root number (BRN), adventitious root number (ARN), stele cross-sectional area (SCSA; mm²), percentage stele area (% Stele), basal respiration rate (Resp.; μmol CO₂ cm⁻¹ s⁻¹), total root length (Tot. RL; cm), specific root length (SRL; cm g⁻¹), and total root dry mass (R Mass; g). Anatomical data were means from the basal segment for each mesocosm/plot. Adjusted coefficient of determination (R²), y intercept (Int.), scaling coefficient (α), and P value (P) for the regression line are shown. Boldface indicates a significant relationship at P < 0.05.

Parameter	Greenhouse								Field
	P Stress				High P				P Stress				High P
	R2	Int.	α	P	R2	Int.	α	P	R2	Int.	α	P	R2	Int.	α	P
TCSA	0.02	0.50	−0.27	0.20	−0.03	1.59	0.003	0.98	0.09	0.99	−0.26	0.06	−0.01	1.22	0.08	0.44
MXA	−0.03	0.51	−0.4	0.79	−0.03	1.60	0.02	0.81	0.04	0.81	−0.19	0.13	−0.004	1.28	0.07	0.35
MXN	−0.03	0.66	−0.06	0.73	−0.02	1.43	0.08	0.51	−0.008	1.24	−0.14	0.39	−0.03	1.16	0.03	0.79
Cond.	−0.03	0.96	0.05	0.64	−0.03	1.59	0.001	0.99	0.10	−0.40	−0.18	0.04	0.01	1.67	0.06	0.25
BRL/RLD	0.52	−2.87	1.90	<0.01	0.003	1.92	−0.18	0.30	0.20	1.23	0.71	0.01	−0.03	1.22	−0.01	0.95
BRWN	0.03	0.36	0.62	0.16	0.02	1.49	0.26	0.20	−0.02	0.86	0.45	0.61	0.10	1.02	0.66	0.06
BRN	0.09	−0.28	0.90	0.05	0.14	1.06	0.57	0.02	0.01	0.63	0.48	0.25	0.08	1.01	0.30	0.09
ARN	0.07	1.07	−0.48	0.08	−0.02	1.63	−0.05	0.48	−0.02	1.24	−0.21	0.57	−0.005	1.03	0.19	0.36
SCSA	−0.01	0.52	−0.10	0.41	−0.03	1.58	0.004	0.97
% Stele	−0.03	0.66	−0.05	0.83	−0.03	1.02	0.28	0.69
Resp.	0.23	−0.87	−0.32	<0.01	0.02	1.92	0.10	0.23
Tot. RL	0.16	−0.47	0.35	0.01	0.10	0.96	0.18	0.04
SRL	0.19	−2.32	0.68	<0.01	−0.03	1.57	0.004	0.98
R Mass	0.69	0.52	0.67	<0.01	0.60	1.10	0.50	<0.01