A study on karyotype of Chinese fir with improved methods of preparing metaphase chromosomes spread

The karyotype of Chinese fir with two improved methods of preparing metaphase chromosomes spread was studied: (1)root tips were treated with 0--4deg C iced-water, 60--72 hours; (2)before with 0--4deg C iced-water 18--24 hours, root tips were treated with 0.05% colchicine 18--24 hours. The result indicated that: the number of metaphase chromosomes appeared more and chromosome spreaded well with the first method. However, there existed the phenomenon of breakpoint or several centromeres in one chromosome. So it was difficult to judge real centromere. The situation can be improved by the second method. The difference between karyotypes treated with two methods was not significant.