Study On The Related Techniques Of Maize Haploid Breeding And Excellent Haploid Inducer Lines Selection In Maize

Maize haploid breeding technique(double Haploid Technology),also known as DH.Because of its ability to shorten the period of 6-8 generations of traditional maize breeding to 2 generations,it has become one of the most important techniques in commercial engineering breeding of maize.At present,the main method of haploid breeding is to use the basic population and haploid inducing lines to produce haploid,and to produce homozygous diploid by natural or artificial chemical doubling.With the increasing competition of commercial maize breeding in the world,haploid breeding technique has been widely used.However,the efficiency of haploid acquisition and doubling has been an important factor limiting the development of DH technique.The purpose of this study was to study DH technique from the aspects of haploid acquisition,identification,doubling and so on,so as to speed up the breeding process and provide references for maize breeding.The main results of this study are as follows:1.Two kinds of haploid induction lines YDX1 and YDX2 were used to induce the basic materials and 275 different parent combinations were produced.According to the phenotype identification of metaxenia of R1-nj gene,the induced rate of flint type female parent was 6.52% and 7.46%,respectively,which was significantly higher than that of half dent type(5.55% and 6.00%).And the induced rate of half dent type was significantly higher than that of dent type(4.03% and 4.77%).And the average induction rate at the top of the ear(9.29%)was significantly higher than that at the middle and bottom of the ear by 3.00% and 3.52%,respectively.2.After chromosome doubled by colchicine treatment,a series of DH lines were bred and matched with other excellent inbred lines.The hybrid combination of DH29 and M5972,17 hybrid 2404,showed high yield and great field characters.3.The induction line YDX1 was used to cross with 3 kinds of different maize of Lancaster,Huang Lv and Reid.After pollination,young embryos were inoculated in MS medium for light culture.Two to Three days later,haploids could be identified by the color of immature embryos and doubled rapidly,and then transplanted togreenhouse culture after seedling refining.The plants could be self-pollinated to harvest the seeds of DH1 generation.The combination of inducer hybridization and tissue culture can further shorten the cycle of traditional haploid breeding to one generation.It is a new haploid breeding method.4.The excellent inducers was selected by crossing between the inducer line and the elite inbred line.According to the morphological marker,statistical analysis of the induction rate was carried out of the selected haploid inducers.The induction rate of the induction lines,S85 and S86 was high,and the genetic markers were significant,the flowering period in the field was long,the amount of pollen was large,and the resistance to lodging was high.The method of the identification of haploid inducers by yellowing seedlings has the advantages of simple operation,accuracy,time saving and labor saving.