[Objective] The purpose was to study the karyotype of onion,explore its better dialysis method and lay a foundation for further studying its genetic improvement.[Method] The technique of making sections of root-tip cells was the key to analyzing the karyotype of onion.The influences of different pretreatment time(1.5,2.0 and 3.0 h),different fixation time(18.0,21.0 and 24.0 h) and different dyeing solutions(acetate-carmine and basic fuchsin dyeing solutions) on the sectioning effect of chromosome from root-...