A Study of Intermittently Induced Polyploidy by Colchicine in Plants

A novel procedure for polyploidy induction,i.e.intermittent polyploidy induction,was developed in this study with garlic root tips as the experiment material.The garlic root tips were soaked alternately in colchicine solutions and tap water until the apex enlarged.Seven colchicine concentrations(0.05%,0.08%,0.10%,0.20%,0.40%,0.60% and 0.80%) were combined with four intervals(3 h,6 h,12 h and 24 h) to form 28 orthogonal combinations and the colchicine treatment without interruption was used as the control.The results showed that intermittent treatment not only alleviated the poisoning and growth-inhibition effects of colchicine to garlic root tips,but also increased the rate of chromosome doubling of the treated apices and that the combinations of low concentrations and short intervals significantly increased the doubling rate.The optimum combination was 0.08% colchicine solution and 3h interval,which gave a chromosome doubling rate of 95.35%.