Study On Trait Evaluation, Genetic Diversity And The Heterotic Relationship Of Hybrid Selections Of Canada Maize Population

The narrower genetic background has became the first constraint factor in maize breeding. The introduction and utilization of exotic germplasm is a sustainable solution for broadening the genetic basic. The introduction and improvement of tropical and subtropical germplasm have already been conducted in China and these have initialy broadened maize germplasm genetic base in China. However, early germplasms are introducted and utilized scarcely, and it has greatly limited the breeding of excellent hybrid. It is the precondition to make use of exotic germplasm that the characteristics, genetic diversity and heterosis crossing with local main germplasm of exotic germplasm can be understood, so it is of importance to enhance breeding efficiency. In this experiment, 151 derived lines which were selected from 7 impoved Canada early corn populations and 7 early elite inbreds in Heilongjiang province were used to evaluate the resistance of 151 lines derived from Canada populations to Head smut and northern leaf blight which were main diseases in Heilongjiang province under the condition of inoculation in the field, understood their main charateristics according to compositive agricultural evaluation, analyzed their genetic diversity by SSR technology, and assayed the combining ability of partial lines derived from Canada populations and the heterosis relationship between these derived lines and early elite maize inbreds in Heilongjiang province to confirm heterotic patterns with NCⅡdesign so as to prepose theoretical evidence on utilizity of these derived lines in early maize districts in China.The main results were as follows :1,Identification of the Head Smut resistance with artificial inoculation showed that :the 151 lines derived from Canada populations, which included 23 resistant materials, 31 middle resistant materials, 66 susceptable materials and highly susceptable materials, and the percent of the resistant and middle resistant materials was 35.8%. Siginificant positive correlation between the derived lines and the parents existed in resistance to Head smut (0.32>0.2080.01,149) Identification of the northern leaf blight with artificial inoculation in 151 lines derived from Canada populations ,it indicated that18 materials were highly resistant , 25 materials resistant, 82 materials middle resistant, 19 materials susceptibel and 7 materials highly susceptible , and the percent of highly resistant, middle resistant and resistant materials was 82%.2,The analysis on main agriculture and production traits displayed that there were difference at 0.01 level in main agriculture and production traits of 151 lines derived from Ca nada populations. It indicated that 40 derived lines was excellent, such as SW1137(Longkang11×EP21),SW1064(Longkang11×EP15).3,336 alleles were detected in 151 lines derived from Canada populations with 65 primers . There were 2~12 alleles per SSR marker with average alleles 5.17 per locus, 0.37~0.88 PIC span(average 0.64). The variation range of gene diversity was0.43~0.89 with the average 0.64. The results above demonstrated that 151 derived lines had abundant genetic diversity. The results of analysis of molecular variety showed the genetic diversity was mainly from population difference.4,151 derived lines were clustered into 6 clusters based on two methods named Genetic Similarity Efficient and Model, namely, Reid population,such as SW1183(B73×EP8);Lancaster population, such as SW1084(MO17×EP3); PA population, such as SW1249(dong237×EP9); Dian11A population, such as SW1236(dian11A×EP3); Dahuang population,such as SW1202(dong46×EP7); Tangsipingtou population, such as SW1289(huangzaosi×EP7).5,the derived lines with excellent GCA effect of 13 agriculture traits and traits related to production included SW1183(B73×EP8),SW1030(8112×EP7)and so on;The combination with higher SCA effect of single plant production were JinQi×SW1030(8112×EP7), Dong46×SW1183(B73×EP8) and so on.6,The stronger heterosis in production of single plant existed between 49 derived lines and partial early elite inbreds in Heilongjiang province.The combination with single plant production over CK Kedan10 accounted for 24.5% of all the combinations, combinations over Suiyu7 maize 19.6%, combinations over Demeiya 1 14.5%. Combinations with single plant production heterosis under the condition of circumstances included dong46×SW1183(B73×EP8),dian11A×SW1052(dan340×EP15),合344×SW1052(dan340×EP15),jingqi×SW1030(8112×EP7),合344×SW1289(huangzaosi×EP7),K10×SW1271(huangzaosi×EP14),dian11A×SW1175(huangzaosi×EP1),KL298×SW1289(huangzaosi×EP7),dian11A×SW1072(MO17×EP6),K10×SW1064(longkang11×EP15)。7,49 lines derived from Canada populations were classificated into 7 clusters according to the SCA effect of average single plant production at two locations, namely, Lancaster population including SW1084(MO17×EP3);Reid population including SW1030(8112×EP7);Tangsipingtou population including SW1289(huangzaosi×EP7); Nvdahonggu population including SW1052(dan340×EP15); PA population including SW1210(dong237×EP23); Dian11A population including SW1236(dian11A×EP3); Dahuang population including SW1156(dong46×EP11);. The classification was consistent with the digree of derived lines.8,According to the analysis of heterosis relationship, main utilization path of heterosis for the lines derived from Canada had Dian11A population×SW1052(Dan340×EP15),SW1175(Huangzhao4×EP1),SW1072(MO17×EP6),Reid×SW1271(Huangzhao4×EP14),SW1064(Longkang11×EP15), Lancaster×SW1289(Huangzhao4×EP7), SW1052(Dan340×EP15). 9,Innovation of this research was as follows: the resistance to maize head smut and northern leaf blight of 151 lines derived from Canada maize populations were evaluated with artifical innoclution in the first time in China; main agricultrue traits and traits related to production of 151 derived lines were evaluated compositively for the first time, and 40 excellent derived lines with good agriculture and production performance were obtained; 151 derived lines with unknown digrees were clustered in the first time; the combining ability and the path of utilizing heterosis of 49 derived lines were investigated and two derived lines which resisted head smut and northern leaf blight synchronously with good agriculture traits and high combining ability were explored from 151 lines derived from Canada maize populations, namely, SW1084(MO17×EP3)and SW1064(Longkang11×EP15).