Studies on seed germination and in vitro shoot multiplication of <i>Satureja khuzistanica</i> Jamzad, an important medicinal plant

Abstract

Satureja khuzistanica Jamzad is an important multipurpose medicinal plant in Iran. The essential oil of S. khuzistanica is characterized by high concentration of carvacrol (93%). The seeds of S. khuzistanica are dormant and have a very low germination under normal conditions. This is the first protocol for in vitro seed germination and plantlet regeneration of this plant. Experiments were done to determine the effects of cold stratification (two, four and six weeks), chemical treatments including various levels of gibberellic acid (GA₃) (50, 100, 200 and 500 ppm), potassium nitrate (0.2, 0.4 and 0.6%), sulfuric acid (50%) and also the synergistic effect between cold stratification and other factors on seed germination of S. khuzistanica. The most germination percentage was achieved when six weeks stratification was followed by 200 ppm GA₃. For shoot proliferation, the node explants were cultured on Linsmaier and Skoog (LS) medium supplemented with different concentrations of benzylaminopurine (BAP) and kinetin (Kn) within the range of 0.5 to 2 μM and combinations of indole-3-butyric acid (IBA: 2 and 5 μM) with BAP (2 and 5 μM). Multiple shoots were obtained from the nodal explants, the higher frequency (77%) of shoot formation was observed in the LS that contained BAP (5 μM) in combination with IBA (2 μM). The best condition for rooting were LS medium plus 2.5 μM of IBA. The rooted plants were successfully transferred to garden soil, exhibiting a normal development.

Key words: Germination, gibberellic acid, growth regulators, node explants, Satureja khuzistanica, stratification.