Table 1.

Michelis–Menten kinetics coefficients calculated for nitrate influx to intact roots of corn grown in hydroponics for 15 or 20 d, deprived for 2 d or 5 d prior to the determination procedure

In each column, values with the same letter are not significantly different at P≤0.05 levels according to the paired t-test. Combinations where net influx (In) responds linearly to the concentration (C) are represented by the linear regression.

Age (d)	Deprivation (d)	Root class	Positiona (cm)	I max(pmol cm−2 s−1)	K m(µM)	C min(µM)	R 2	n
15	2	Lateral	0–4	14.66 g	2.68 d	1.70 c	0.82	10
20	2	Lateral	0–4	45.25 a	10.67 c	4.40 ab	0.68	9
			4–8	35.81 ab	17.25 bc	1.64 c	0.84	5
20	5	Lateral	0–4	30.54 ab	21.33 bc	4.69 ab	0.55	15
			4–8	In=0.4044×C+2.4268			0.79	8
15	2	Seminal	0–4	26.64 bc	10.50 c	2.82 bc	0.79	14
			4–8	22.17 c	16.10 bc	2.06 c	0.64	14
20	2	Seminal	0–4	33.76 b	10.31 cd	3.79 a	0.70	18
			4–8	30.03 ab	6.72 cd	4.68 ab	0.67	9
15	2	Crown	0–4	14.02 d	15.70 bc	2.36 c	0.82	14
			4–8	24.30 c	52.21 a	0.98 c	0.90	14
20	2	Crown	0–4	41.25 a	32.74 ab	6.20 a	0.82	9
			4–8	46.52 a	45.49 ab	4.28 ab	0.95	18
20	5	Crown	0–4	In=0.2502×C+1.9036			0.66	18
			4–8	In=0.3365×C+0.2930			0.95	18
20	2	Brace	0–4	16.47 cd	28.21 ab	3.22 abc	0.81	6
			4–8	In=0.3357×C+0.9501			0.92	7
20	5	Brace	0–4	In=0.2183×C–0.4755			0.73	13
			4–8	In=0.2949×C+1.2704			0.86	5

^a Distance from the root tip.