Effects of salt stress and water deficit on plant growth and essential oil content of lemon balm (Melissa officinalis L.)

Studies were carried out to determine the effects of salt stress (0.25, 1.00, 2.00, 4.00 and 6.00 dSm(-1)) and water deficiency (0, 12.5, 25.0, 37.5 and 50.0%) on some yield components and essential oil contents of lemon balm (Melissa officinalis L.). The results showed moderate tolerance of lemon balm against salt with death of all plants when irrigation water had salinity level of 6 dSm(-1). Dry yield per plant under salt stress varied between 4.33-14.87 g with maximum yield at 1 dSm(-1) salt concentration. Lemon balm was found highly tolerant against water stress. Dry yield under water deficit varied from 13.05 to 19.20 g per plant. Reduction in yield was not statistically significant till 25 % water deficiency. Each increase in salt stress was accompanied with reduction in essential oil, whereas its ratio increased with each increase in water deficiency