Genetic Study On Maize Exotic Improved Lines In Different Densities

With development of the breeding technology,the problem of the narrow germplasm was revealed,and this problem limit the development of our country’s maize breeding technology. So use the exotic maize germplasm has become a approach to solove the problem of narrow germplasm.This study use7exotic improvement lines and6common inbredlines,42combinations was produced with incomplete diallel cross.Field trial set up3densities,60000plant·ha,75000plant·a and90000plant·ha.Ivestgated the hight of plant and other traits related to the yield.Collected and reorganize the data, estimated of GCA,SCA and reference heterosis were calculated based on the means of combinations. The main rsults were summarized as follow:1. The estimates of GCA effects showed that, J7923performanced high GCA effects on the traits:hundred grain weight,ear rows and seed ratio. PH6WC performance high GCA effects on hundred grain weight and other5traits.Zheng58performanced high effects on hundred grain weight,ear rows and other traits.Mo17performanced bad on yield and other traits,but has high GCA effects on ear length,it can be used in improved this trait.So the3inbredlines (PH6WC,Zheng58and J7923) from Reid had high yield potential and good performance in3different high desenties.And a tropical inbred line J666also had a good performance in yield and other traits.So the inbred line from Reid group can be as the good material to produce the density-independent hybrid.2. Through comparing the exotic maize improved lines and common inbred lines in China,the result showed that the improved lines had better performance on the yield and other yield components GCA effects, the yield potentia higher is than the native common inbred line.So the utilization of the exotic improved line can broden the germplasm resource in China effectively.3. Through the estimates of SCA and the analysis of the reference heterosis,the results show that exotic inbredlines and the text lines had high yield potential.Under3densities,there were several combinations better than the excellent hybrid Zhengdan958.The performance of J7923×J666is the best.And the heterosis pattern is Reid×PN,and this pattern can be used in density-independent maize breeding.4. Estimation of population genetic parameter indicated that:the density has not obvious influence on the genetic parameter.The order of the variance of each trait GCA Vg(%)was reverse to SCA Vs(%),the traits of GCA variance were greater than SCA variance including Plant Height,Ear Height,Ear Rows, Ear Diameter,Seed Hundred Grains and seed ratio.This indicated that these traits mainly influenced by additive effects,and non-additive genetic effects relatively weak.Ear row numbers,seed ratio,plant height and ear height,the broad and narrow heritability of these traits was high,and appropriate foe early generation selection.5. Path analysis showed that:in high density,the greatest direct positive effect to yield is100-kernel weight,and the greatest direct native effect to yield is barren length. With the density increased,the native effect of barren length became more obvious.So in the density-independent maize breeding,the100-kernel weight and the length of barren should be emphasized.