Maize High-frequency Induce Line Screened And Haploid Doubled Technology

We can obtain homozygous diploid material quickly and improve the efficiency of maize breeding significantly by haploid breeding method. Now, parthenogenesis is usually induced by in vivo inducing the maize haploid, this method solves the problem of a large number of accesses to maize haploid. Low induced rate and chromosome double technology are the bottleneck to restrict using haploid in practice, which is researched worldwide extensively. This study includes four parts:1) Induction frequency of different Stock6 derived lines; 2) Identification precision of the haploid grain; 3) Pathways of haploid plants normal doubled; 4) Haploids'chromosome double method. Now the main results are summarized as follows:1. The variation of induction rate to different Stock6 derived lines between Hua24 and Green superman was large, the variation range was 0-13.82%. Four of derived lines, H522, H524, H538 and H542, their average induction rate over 6%, the average induction rate of H538 were highest, which reached at 11.9%. There is same trend of induction rate between two females to different Stock6 derivative (coefficient of correlation r=0.85, p<0.05);2. Haploid can be accurately identified by Navajo markers on grain, color of the seedling's coleoptile, root and growth rate. Accuracy rate of identification of the Hua24-haploid seed was 87.50% which was significantly higher than the other three materials.3. There are two pathways for maize haploid natural double, fertility gametes pathway is the primary means, sporophyte natural doubling of maize haploid is the secondary channels. The two factors can affect the efficiency of fertility gametes pathway:(1) Genotype of haploid. The doubled rate of Hua24 by fertility gametes pathway was 47.71% in 2008. (2) Environmental conditions. In 2009, encountered high temperature, drought when flower shedding, the doubled rate of Hua24 by fertility gametes pathway was down to 0.4. Treat time was the most important factor that affects the efficiency of double dipping shoots. Compared the results of L17 and T688 dip bud, we can know 8h was the best time scale, the average doubled rate of L17 and T688 reached 5.63% and 17.62%, which was significantly higher than the other processing time. High death rates were the biggest problem to soaked bud method need to solve. In this study, the death rate of L17 and T688 was more than 60%. 5. The microinjecting method had affections on 4 kinds of material. The affection of Hua24 is best, average doubled is 27.84%, and the highest doubled rate reached 37.50%. The biggest advantage to microinjecting method is lower death rate. The deaded plants of L17 were least; of which average death rate was 10.10%.The results of this study to the pathways of maize haploid natural doubled, induction frequency of different Stock6 derivatived lines and chromosome double method have some guidance to choice of high-frequency induce line, and create a system about chromosome doubling. That accumulates experience and settles the foundation for the application of the haploid technology in practice, in future.