Cholodny–Went model

[citation needed] The model was independently proposed by the Russian-born scientist Nikolai Cholodny of the University of Kyiv, Ukraine, in 1927 and by Frits Warmolt Went of the California Institute of Technology in 1928, both based on work they had done in 1926.

[3] Went's 1926 experiment appeared to demonstrate that auxin moved towards the shady side of the tip of the coleoptile, the pointed protective sheath covering the emerging shoot.

[7] A 1987 paper reported results indicating that geotropic curvature of both roots and shoots could be explained by local migration of auxin from one side to another rather than by movement along the whole length of the organ.

Critics have also had problems with the reliability of Went's small sample sizes and use of agar blocks instead of actual auxin concentration measurements.

[9] In 1990–1991 Moritoshi Iino in Tokyo made measurements of IAA (auxin) in maize coleoptiles in response to both light and gravity.

[6][11] A study of Arabidopsis reported in 2000 showed that basipetal (from the tip) transport of auxin controlled gravitropic responses in the roots of these plants.