Observation Technology of Root Tip Chromosome in Cassava

[Objective]The research aimed to explore the root tip squash technique of diploid cassava and provide references for the identification of the polyploid.[Method]With root tips of cassava variety Huanan 124 as tested materials,they were treated with 1 mol/L HCl in water bath at constant temperature to conduct cell dissociation and time gradient test for 11～15 min so as to seek for the optimum dissociation time.The observation methods of root tip chromosome(diploid) in cassava were discussed through the dissociation and observation experiment on root tip chromosome in cassava.[Result]The optimum sampling time for cassava root tips was at 9:00～10:00 a.m.on the day after a rainy or watering day.The time gradient experiment of dissociation showed that the optimum dissociation effect of cassava could be got while dissociating for 13 min.The optimum reagent,which was selected out through comparing the staining effects of 4 staining reagents(I-IK coloration solution,improved phenol fuchsin,safranine staining solution and aceto carmine),was improved phenol fuchsin.[Conclusion]The research provided a new method for the direct identification of polyploid cassava.