The present study was conducted to polyploidy possibility induction of two Iranian endemic mint (Mentha mozaffarianii)ecotypes. For this purpose, three experiments were done. The first experiment was factorial, based on completely randomized design with three factors and three replications that rhizomes were used for treatment. The first factor including different colchicine concentrations (0, 0.025, 0.05, 0.1 and 0.2% that 0 as control). The second factor including two Mentha ecotypes (Ecotype A: Kamarej region and Ecotype B: Pirmohlat region) and the third factors consist of two soaking time (6 h and 12 h). In second experiment, apical meristem was treated. The factorial experiment based on randomized completely design with two factors and five replications. The factors including different colchicine concentrations (0, 0.035, 0.07, 0.15, 0.3 and 0.7%) and two ecotypes. In the third experiment, colchicine as combined with irrigation was applied. For this purpose, a factorial experiment in randomized complete design with two factors (colchicine concentrations: 0, 0.025, 0.012, 0.006% and two mint ecotypes) and three replications was conducted. At the end of all experiments, survival rate and tetraploidy percentage (by morphological change, stomata traits, flow cytometry and chromosome counts) were measured. The results showed that different treatment had significant effects on survival percent on all experiments and increasing of colchicine concentration caused decreasing plants survival. On the other hand, tetraploidy changes only in the first experiments were observed. Only in 0.025% colchicine treatment with 6 h soaking time on ecotype A, 12.66% tetraploidy was identified. Totally, it is seems that Mentha mozaffarianii hardly response to colchicine for tetraploidy induction.

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