Table II. Stem water δ¹⁸O of eight maize genotypes and proportional water use by depth.

Data are means ± se of δ¹⁸O of stem water (n = 4) measured for eight maize genotypes contrasting in lateral root branching density (FL or MS) and proportional water use by depth from different soil layers (deep is the aggregate of three deep soil layers) under WS conditions at anthesis in AZ and PA.

Classification Based on Lateral Root Branching Density	RILs	δ18O of Stem Water		Proportional Water Use by Depth
		AZ	PA	AZ			PA
				10 cm	20 cm	Deep	10 cm	20 cm	Deep
				%
FL	67	−7.66 ± 0.17	−9.69 ± 0.11	10.20	10.20	61.15	9.65	25.58	64.78
	79	−7.89 ± 0.21	−9.94 ± 0.51	9.28	8.90	65.58	8.18	25.83	66.00
	86	−7.62 ± 0.13	−9.76 ± 0.35	10.98	10.70	59.28	9.18	25.60	65.28
	327	−8.46 ± 0.36	−9.91 ± 0.40	5.60	5.15	80.10	8.23	24.43	67.33
MS	134	−5.39 ± 0.23	−6.49 ± 0.26	26.85	41.60	11.20	56.38	27.03	16.65
	295	−5.21 ± 0.22	−6.98 ± 0.0.27	36.45	35.80	9.15	41.68	41.43	23.90
	321	−5.59 ± 0.21	−7.01 ± 0.37	29.88	28.80	14.70	47.55	32.60	19.85
	362	−5.44 ± 0.25	−6.87 ± 0.11	30.65	33.03	12.85	48.53	32.15	19.33