Effects of Salicylic and Acetylsalicylic Acids on the Scotonastic and Photonastic Leaflet Movements of Cassia fasciculata

Salicylic and acetylsalicylic acids applied on excised leaves of Cassia fasciculata modify the dark-induced (scotonastic) and light-induced (photonastic) leaflet movements. They inhibit the scotonastic movements in a dose-dependent manner from 1 × 10⁻⁴ to 1 × 10⁻³ molar and they promote the photonastic movements at an optimum concentration of 5 × 10⁻⁴ molar. These results suggest that these phenolic compounds do not act specifically on the K⁺ uptake, which was shown to be inhibited by their action on other materials.