The effect on root geotropism of certain ortho‐carboxyphenylpropanones

A series of compounds related to 1‐(2′‐carboxyphenyl)‐3‐phenylpropane‐1,3‐dione has been synthesised and their effects on root geotropism assessed using cress and ryegrass seedlings. The more active members have been found to be highly potent, abolishing root geotropism at concentrations as low as 0.01 mg/litre. In this respect they compare favourably with TIBA and NPA. It is suggested that a 2‐carboxy‐phenyl radical separated by a 3 carbon unit from a second aromatic ring is essential for activity, and that a C‐1 oxygen function enhances the effect.