Effect Of Regeneration Population Size On Change Of Genetic Integrity In Maize Landraces

Renovated population size is a very important factor that affects the genetic integrity of maize. Theoretically speaking, the larger the renovated population size, the less the genetic drift. However, in actual operation, renovated population size is limited due to human labor, material cost and financial shortness. In order to resolve this conflict, suitable renovated population size was put forward. It refers to a population size with small genetic drift and low frequency genes were well-preserved. In this thesis, genetic alteration of seeds of 50, 100, 150 and 200 plants of maize landraces, Tiaohuanuo, Hengqunhei and Jiahongzao were analyzed using SSR markers, to find the suitable renovated population size of maize, so as to provide scientific and theoretical basis for making a criteria for regenerating germination resources. Main results found were as follows:(1) The number of alleles, rare alleles, polymorphic loci, polymorphic loci percent, alleles per loci, index of genetic diversity and Shannon index were lower than their previous generation group CK. "Bottleneck effect" exists between two generations.(2) Renovated population size have an impact on the genetic integrity of germplasm. Population size of 200 performed better on maintaining genetic integrity of the original germplasm. Compare to other three groups, population size of 200 can maintain the genetic integrity better.(3) Different maize varieties have different genetic composition structure. Suitable renovated population size should be determinate in accordance with the complexity of maize genetic composition structures.