Table 1. Potency of chemicals and reversibility of their effects.

	Inhibition of gravitropism, IC50*		Inhibition of growth		Inhibition of hypocotyl bending		Vacuolar effects
Chemical	Hypocotyl	Root	Hypocotyl length†‡	Root length†‡	Inducible	Reversible	Reversible
2,4D	NA	0.02 M	NA	96.8 (0.02 M)	ND	ND	ND
5403629	0.08 M	0.2 M	90.4 (0.1 M)	60 (0.3 M)	Yes	Yes	Yes
5271050	2 M	NA	88.7 (2 M)	NA	Yes	Yes	No
5850247	0.2 M	0.3 M	93.8 (0.3 M)	98.8 (0.3 M)	Yes	No	Yes
6220480	NA	8 M	NA	21.8 (10 M)	NA	NA	Yes

NA, not applicable, because chemical has little or no effect on gravitropism. ND, not determined.

^*Estimated concentration resulting in 50% inhibition after 24-h gravistimulation.

^†Lengths are reported as a percentage of the untreated controls.

^‡Length measurements performed at the concentrations indicated.