Abstract:
In this study, freezing time at 0.01% colchicine was practiced to observe chromosome from Exacum
ritigalensis. Fifty, two weeks old seedlings of E. ritigalensis were randomly selected and all actively
growing root tips about 10mm in length were excised from each plantlets. These root tips were washed
with tap water to remove the residues of the medium. Root tips treated with 0.01% colchicine solution
were kept at room temperature for either two hours (control) or at at 4°C for either 1,1.5, 2 and 2.5hrs.
The experiment followed a completely randomized design with ten replicates were used for each
treatment Treated root tips were placed on glass slide and stained with one drop of carbolfuchsin
solution and were observed for chromosomes under a microscope (Axio Lab A l), and photos were taken
with the associated apparatus. Then they were ranked using a scale 0,1,2, 3, and 4 from 0 to 4 (very poor,
poor, satisfactory, good and very good), according to the viisibility and for clearness of chromosomes in
cells; Statistical analysis was performed by Wilcoxon sign rank test using SPSS statistics package (version
20). It was observed that Exacum ritigalensis diploid plants with 28 chromosomes and also results
revealed that two hours freezing at 4°C gave the best picture of chromosome than other treatments.
