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چکیده
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Stevia rebaudiana Bertoni belongs to family Asteraceae. The leaves of stevia are about 200-300 times sweeter than sugar with no calories that are the source of glycosides. Plant tissue culture is the growth of tissues or cells separate from plants that is a rapid tool for propagation of stevia. In this research we studied the effect of various concentrations of nitrogen on some morphological features of stevia under in vitro conditions. We used axillary nodes as explants and they were cultured on Murashige and Skoog (MS) medium containing inorganic nitrogen sources i.e. NH4NO3 (0, 825 and 1650 mg/l), KNO3 (0, 950 and 1900 mg/l) were observed.. The cultures were kept for 4 weeks at a temperature of 25±2°C with a photoperiod of 16/8 hour low light/dark each day. Maximum shoot length (89.33 mm), dry weight of plants (0.10 mg) and leaf fresh weight (0.42 mg) was observed on a MS medium with 1650 mg/l NH4NO3 and 950 mg/l KNO3. Minimum shoot length (6.13 mm), root length (6.60 mm), leaf number (4.26), leaf dry weight (0.01 mg), leaf fresh weight (0.05 mg), total dry and fresh weight (0.02 and 0.15 mg) and growth rate was observed on a MS medium without nitrogen sources. Moreover, presence of nitrogen sources increases both shooting and rooting in stevia rebaudiana Bertoni.
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