The effect of Cytokinin and Gibberllic acid on seed germination and growth traits of Lemom balm

Melisa officinalis L. or Lemon balm; is belonged to Lamiaceae family is one of the most importan p;ant medicinal. The therapeutics effects of Lemon balm such as, antispasmodic and digestive effects have been demonstrated. Due to low small size of seeds, seed germination and fallow it primary growth will be affected. Seed used in this research were purchased from Pakban Company, Ispahan, Iran and then were surface sterilized in 1 % chloramineT for 3 min. Potato dextrose agar (PDA) medium was used for seed germination assay. The effect of tow cytokinin and gibberllic acid hormones at concentration of 50 and 100 mM in single and combination form was investigated in a factorial based on completely randomized design. Growth seedling were cultured and growth under pot culture containing peat moss and then some characteristics including germinated seeds, vigor index, seedling dry weigh, seedling length and coleoptile length were measured. Mean comparison analysis showed all used treatments have a significant effect at the level of 1% among tested parameters. The highest effect of treatment on seed germination was related to two hormones combination at 100 mM concentration and the lowes effect was recorded in Cytikinin application at 50 mM concentration. Our observation did not show any significant different and effect of culture medium on seed germination in compared to sterile water. Based on obtained data in this research, use of plant hormones at low concentration and in combination form is suggested to seed germination improvement and increase of growth parameters.