Induction, Ploidy Determination And Endopolyploidy Of Polyploid In Lagerstroemia Indica L.

Lagerstroemia indica L. has been palying an important roal in Landscape Application,because its beautiful colors and long blooming time. Changing ploidy level will lead tophenotypic change, such as flower color, presbyopic glasses, plant morphology, which willprovide new breeding material for plant breeding. Contact process with colchicine to obtainpolyploid plants is one of the most simple and effective processes in ploidy breeding. Thispaper was committed to polyploid induction experiment on germinating seed and cotyledonsstage seedling of Lagerstroemia indica L., using different combinations of colchicineconcentration and duration, and the evaluation on induced materials by morphology compare,pore compare, chromosome counting and flow cytometry. The Main research results asfollows：1. Effect of induced resistance was different within different colchicine concentrationand duration. Induction rate of treated material increased following the augment of colchicineconcentration and duration, but dath rate increased at the same time. So in this paper, we useinduction efficiency to evaluate the effect of induced resistance of colchicine.Treating germinating seed with colchicine can acquire higher induction efficiency,compare with treating otyledons stage seedling of Lagerstroemia indica L., we treatedgerminating seed with one-time-seed-length radicle for48hours using0.1%colchicinesolution, wihich induction efficiency was72.00%,while it was60.00%on treatment ofcotyledons stage seedling with1.6%colchicine for96hours.2. Tetraploid (2n=4x=96) and hexaploid (2n=6x=144) plants were successfully inducedfrom seedling of Lagerstroemia indica L. by processing shoot apical meristem withcolchicine.3. The results indicated that the variants, which were characterized by stunted but stoutplant, wrinkled and thicker leaves, less stoma frequency, larger(length rised by65.79%andwidth,45.01%) guard cells (a pair, the same as below), more larger(rised by80.25%)chloroplasts in each pair of guard cells, were significantly different from the diploid plants inmorphology. Tetraploid plant got markedly larger (rised by59.07%) pollen grains, slightlylarger petals, longer inflorescence but less flowers than diploid plants. 4. Endopolyploidy was observed in both induced tetraploid plant and diploid plant, andendopolyploidy degree of the former was lower than that of the latter. C-value in tetraploidplant was0.2105, while that was0.5313in diploid plant.