Investigation the effect of different nickel sulfate concentrations on growth and germination indices in Daenensis and Garden Thyme species

Thyme is a medicinal plant in the Lamiaceae family. According to no certain reports about tolerance or accumulation of nickel in native thymes Iran and also its various forms is used in various industries, accordingly, the effect of different levels of nickel sulfate (0, 10, 25, 50 and 100 μM) on growth and germination indices of two thyme species including daenensis (Thymus daenensis) and garden thyme (Thymus vulgaris) in a completely randomized design with three replications laboratory conditions (petri dish, hydroponics and in vitro) were evaluated. Two weeks after the above treatments, germination and growth indices were investigated. In hydroponic culture, obtained results showed that root length, root dry weight and chlorophyll content was decreased by increasing of nickel sulfate concentrations. According to the results of this experiment, it seems to daenensis thyme was more tolerant to this stress than garden thyme. In in vitro experiment, with increasing levels of nickel sulfate, reduction of root length was observed so the reduction in daenensis thyme was more severe than garden thyme. In this experiment, root length in the levels of 25, 50 and 75 μM nickel sulfate showed non-significant difference in garden thyme, but this difference was significant in daenensis thyme.