Objective To induce maize haploid and double monoploids.

Method The F₁ generation hybrids of high resistance head smut inbred line K88 and high sense of head smut inbred line G115 of North corn regional were chose as female parents, which hybridized with male parents of 5 haploid inducers (JS6-11 - JS6-15) conduct maize haploid inducing test. Colchicine was used as maize haploid artificial chromosome doubling agent. Four approaches (dipping root method and dipping bud method, dipping heart leaf method and acupuncturing growing point method) were taken to conduct maize haploid doubling test and each set 3 concentration gradients (0.2, 0.4, 0.6 mg·mL^-1), using DMSO at volume fraction of 2%+glycerol solution 5% as auxiliary reagents.

Result and conclusion Filament lengths and the time of pollination had significant effects on the haploid induction. The haploid induced rate of longer silk (≥7 cm) pollination was 17.0% on average, almost 3.3 times higher than that of shorter silk (≤4 cm) pollination. Haploid induced rate of pollination was 18.4% on average after midsummer, almost 3.4 times higher than that in midsummer pollination. The results showed that late pollination and low temperature increased haploid inducing frequency. Maize haploid doubling tests showed that the plant survival rates of dipping root were lower than 50%. Acupuncturing growing point method at concentration of 0.6 mg·mL^-1 and dipping heart leaf method at concentration of 0.4 mg·mL^-1 with the fertility rate of plants 45.9% and 28.9%, respectively, with maturing rate of two methods, 15.2% and 11.1%, respectively. Acupuncturing growing point and dipping heart leaf methods are better options for chromosome doubling.