Genetic Diversity And Yield Components Among Maize Inbred Lines Of Hybrids In China

Maize(Zea mays L.)is one of the most successful and earlist cases in the crops that applied heterosis as the main approach to increase production. In application of heterosis, it is essential to uncover the relationship between yield composition of parents and heterosis and further to guide choice of parents. Using 30 famous hybrids from 36 parents from 1950's to now, it studied the changes of important traits related to yield among 50 years; and the relationship between parental traits and heterosis and yields of their hybrids, to uncover the paterns of increasing yield and heterosis. In addition, using 70 SSR markers, it studied the genetic diversity and population structure of the parents and the relationship between population structure and heterosis.The main results are as follows:1.The analyzes result of trial in Beijing and Xinjiang shows that each age of hybrids of 1950's and from 1970's to 2000's hand over to sow in the different on trial density and different age species yield to increase a benefit to all exist obvious difference. Different age grow of the species is an ecosystem area in the adverse circumstances severity regardless or in the adverse circumstances under light condition all obtained aggressive improvement result. Our country of lately hybrids hand over to sow in the anti- negative aspect of anti- a ratio old and hybrids handed over to grow to obtain aggressive improvement progress.2. The analyzes result of density shows that the breeding of maize has been stay around medium low density level for long time and the target of high density breeding of Maize didn't get valid implementation in the our country. It is the valid path that enlarge density and raise 1000 kernel weight for raises yield of maize.3. Under the low density condition that the hybrids kind advantage to the yield increase of the contribution rate compare greatly. However, with increase of high density as newer era coming the heterosis will contribute less and less percentage for yield enhancement and at the same time non-heterosis will do more and more percentage.4. The analyzes result of agriculture traits shows that our country the different age hybrids to hand over to grow of the main the agriculture form the get true the valid of the just to improvement. It is the main reason that the aggrandizement density and the increment kernels per ear and raise 1000 kernel weight for raise yield of maize.5. Seventy SSR markers revealed 248 alleles in 45 inbred lines and 4 maize OPVs. The average number of alleles per SSR locus was 3.54. The polymorphism information content (PIC) for the SSR locus with an average of 0.56. The UPGMA method grouped them into six clusters which were consistent with their pedigree information.6. The OPV species and other of maize germplasm have farther relation in the blood relationship and the germplasm resources foundation extensively. It is will have very important meaning for grow germplasm to expand, improve , creative and selection inbred lines etc.s.