Changes in Leaf Phenols and other Physiological Parameters of Peppermint in Response to Olive Mill Wastewater Application

We studied changes in physiology of peppermint (Mentha piperita) exposed to olive mill wastewater (OMW) toward the moment of OMW application, the dose applied and the stage of plant growth. The biomass, hydrous state, chlorophylls in leaves and total proteins in roots were generally reduced by OMW spreading except for spreading 218 d before implantation. Peppermint shoots were more sensitive to phytotoxicity than roots. Determination of leaf phenols showed that mint roots facilitate the absorption and transfer of OMW phenols to leaves that are more sensitive to OMW toxicity. Phenols accumulation in leaves was as high as the dose spread was higher. Significant variations in leaf phenols were obtained depending on time of OMW spreading