Table I.

Root citrate exudation rates (pmol root⁻² h⁻¹) of six maize genotypes exposed to different Al³⁺ activities

Exudation collections were performed at two different 24-h period intervals (Day 1–2 and Day 3–4). Genotypes have been sorted from left to right in order of decreasing Al resistance. The values are the mean of six replicates ± the SEM.

Time Interval	Al3+ Activity (μm)	Decreasing Al Resistance
		Cateto-Colombia	→	Pioneer 3355	→	Mo17	→	B73	→	L53	→	11×726
Day 1–2	0	0 ± 0		18 ± 10		91 ± 22		0 ± 0		0 ± 0		11 ± 11
	5	33 ± 4		67 ± 40		173 ± 116		5 ± 5		0 ± 0		48 ± 26
	10	41 ± 1		105 ± 23		675 ± 183		42 ± 12		28 ± 19		53 ± 15
	20	203 ± 57		137 ± 44		511 ± 225		61 ± 40		301 ± 41		139 ± 9
	40	368 ± 95		221 ± 82		829 ± 332		17 ± 10		309 ± 15		297 ± 99
	80	324 ± 70		769 ± 168		911 ± 172		44 ±15		249 ± 59		284 ± 67
Day 3–4	0	0 ± 0		9 ± 9		194 ± 88		8 ± 5		0 ± 0		4 ± 4
	5	33 ± 19		74 ± 63		38 ± 14		206 ± 70		12 ± 12		203 ± 55
	10	120 ± 42		215 ± 74		523 ± 139		204 ± 78		22 ± 14		193 ± 17
	20	236 ± 71		590 ± 114		298 ± 97		153 ± 24		107 ± 51		138 ± 16
	40	441 ± 98		613 ± 153		572 ± 122		181 ± 65		449 ± 53		317 ± 44
	80	484 ± 131		883 ± 446		1,481 ± 399		44 ± 17		671 ± 209		539 ± 183