Action of Benzoic Acid and its o-, m- and p-Hydroxy-Derivatives on the Dark- and Light-Induced Leaflet Movements in Cassia fasciculata Michx.

Benzoic acid and its o-, m- and p-hydroxy derivatives appliedon excised leaves of Cassia fasciculata modified the dark-induced(scotonasty) and light-induced (photonasty) leaflet movements.Benzoic acid inhibited the scotonastic closure in a dose-dependentmanner from 10^–4M to 10^–3M and promoted the photonasticopening at optimum concentration of 5.10^–4M. These effectswere dependent upon the position of hydroxyl group on the benzoicring, the o-derivative inducing a stronger effect than the m-and p-derivatives. Experiments showed that treatment with o-hydroxybenzoicacid had not to exceed 30–60 min and that the maximumeffect was obtained at pH 5.5. (Received September 16, 1986; Accepted June 22, 1987)