Melatonin enhances root regeneration, photosynthetic pigments, biomass, total carbohydrates and proline content in the cherry rootstock PHL-C (Prunus avium × Prunus cerasus)

► Melatonin at concentrations of 0.05-1 μM positively influenced root elongation of the PHL-C rootstock. ► High melatonin concentrations significantly increased carbohydrates and proline level of leaves of the PHL-C rootstock. ► Rooting of the PHL-C rootstock was inhibited when high melatonin concentrations (5-10 μM) were added in the substrate. ► Chlorophyll and porphyrins concentration substantially increased with 0.1 and 0.5 μM melatonin.