The effect of organic matter and type of culture medium on vegetative ‎characteristics, enzymatic activity and essential oil of lemon balm (Melissa ‎officinalis L.) under salinity stress

In order to study the effect of organic matter and type of culture medium on vegetative characteristics, enzymatic activity and essential oil of lemon balm under salinity stress, a factorial experiment based on completely randomized design with three replications in Jahrom city of Fars province carried out. The first factor was the medium culture at three levels (compost + soil, vermicompost + soil and compost + vermicompost + soil (all in equal proportions)), the second factor was organic matter at two levels (humic acid (HA) and effective microorganisms (EM)( concentration of 5 per thousand) and the third factor was salinity at three levels (515, 3656 and 7312 μm / cm). The results showed that with increasing salinity, proline content and activity of catalase and peroxidase enzymes increased and plant height, leaf number, chlorophyll and percentage of essential oil decreased. Co-addition of vermicompost and compost to soil on growth and physiological traits was more effective than either of these two substances alone. In general, the use of organic matter and effective microorganisms in the culture medium containing soil+ compost+ vermicompost reduced the negative effects of salinity on lemon balm and the use of organic matter and effective microorganisms can improved plant tolerance under salinity stress conditions and increased the growth characteristics and essential oil content of this medicinal plant.