Haploid seedlings were inducted from different maize materials.At 2-3-leaf stage,maize haploids were treated with 0.06% colchicine and 2.0% dimethyl sulfoxide（DMSO） by dipping root,dripping heart leaf and acupuncturing growing point,respectively.The doubling rate and mortality rate in different treatments were analyzed by variance analysis and multiple comparisons.The result showed that growing point acupuncturing method exhibited the highest doubling efficiency with an average doubling rate of 23%,seed-setting rate of 21.4%,and mortality rate of 16.3%.Composed with other two chemical doubling methods,growing point acupuncturing method significantly improved the doubling rate of maize haploids with a lower application dose of colchicine.This study laid the foundation for industrial application of haploid breeding techniques.
