Influence of phenolic acids on morphological changes in roots of Pisum sativum

At relatively high concentrations (1 mM), ferulic, vanillic, p‐coumaric, p‐hydroxybenzoic, syringic and caffeic acids inhibited the growth of roots of Pisum sativum L cultured in a Hoagland nutrient solution under axenic conditions. These phenolic acids also profoundly affected root morphology in terms of extension growth of the main root and the number and size of the lateral roots. The precise growth effects depended on the phenolic acid. At concentrations that inhibited an increase in the length of the main root, the phenolic acids also inhibited cell division. To produce the maximum growth effect, the phenolic acids must be present continuously. Lower concentrations (1 μM)of the phenolic acids also affected root growth and morphology when the nitrogen content of the nutrient solution was limiting.