Induction and Identification of Tetraploids in Eucommia ulmoides Oliv.

Stem primodia of Eucommia ulmoides Oliv. seedlings were treated with different concentrations of colchicine solution at different stages in order to figure out the best inducing method and obtain tetraploids. The results showed that, apart from 0.05% colchicine solution for 48 h, the treatments (0.1%, 0.2% or 0.4%) were all suitable for 12 h, in which the rates of mutants with morphological characteristics varied from 43.3% to 63.3%, the optimum treatment combination was 0.1% colchicine solution for 12 h, and the rates of vatiant plants and tetraploid plants were 63.3% and 36.7%, respectively. The results of chromosome counts indicated that 47 plants were tetraploid plants (2n=4x=68), taking up about 31.76% among the 148 variant plants. This result was consistent with that analyzed with the 'Flow Cytometry' method. The plants showed the general characteristics of tetraploids, such as thicker leaf, smaller leaf index, larger guard cells, less stomata per unit area and more chloroplasts in guard cells.