Research On Heterosis And Genetic Characteristics Of Reid Germplasm DH Germ Line Of Maize At Different Densities

The germplasm of Reid has great potential for maize breeding and production application at home and abroad which shows good agronomic traits of better maize ear,plant type and outstanding characters of high leveled generally combining ability,etc.With regards to this,this experiment used the important germplasm of Reid's population: J1491,J1492,J1493,J1495,J1498 and core germplasm PH6 WC as the material to construct the basic population,and through the DH breeding technology,bred and screened 6DH6,6DH7,6DH9,6DH10,6DH12;By using these DH lines as female parents and non-Reid important germplasms J1673,J1584,J9D207,J1628 and J1674 as male parents,25 cross combinations(5X5)were designed according to NC II.Heterosis and combining ability of yield and main agronomic traits were studied under three densities of 60,000 plants/ha,70,000 plants/ha and 80,000 plants/ha.The results are as follows:1.The results showed that the highest value of the cross combination of 6DH7/J1628 was 117.94% at 60,000 plants/hectare density,the highest value of the cross combination of 6DH7/J1628 was 121.63% at 75,000 plants/hectare density,and the highest value of the cross combination of 6DH7/J1628 was 120.57% at 900,000 plants/hectare density.The group of over-standard advantage results have the same trend,where the highest value of the cross combination of 6DH7/J1628 was 53.20% at 60,000 plants/hectare density,the highest value of the cross combination of 6DH7/J1628 was 30.79% at 75,000 plants/hectare density,and the highest value of the cross combination of 6DH7/J1628 was 34.78% at 900,000 plants/hectare density.According to the results of heterosis analysis,under 3 densities,the best yield heterosis combination of 25 cross combinations was 6DH7/J1628.According to the results of heterosis analysis,under 3 densities,the best yield heterosis combination of 25 cross combinations was 6DH7/J1628.2.The results of general combining ability analysis showed that under three different densities of 60,000 plants per hectare,75,000 plants per hectare and 90,000 plants per hectare,the highest yield effect value of female inbred line was 6DH7,and that of male inbred line was J1628;the highest ear weight of female inbred line was 6DH7,and that of male inbred line was J1628;the highest 100-seed weight of female inbred line was 6DH7,and that of male inbred line was J1628;and the highest ear length of female inbred line was J1628.The inbred line is 6DH7 and the male inbred line is J1628.According to the results of comprehensive analysis,the female inbred line 6DH7 and the male inbred line J1628 were the best.3.The results of special combining ability analysis showed that under three different densities of 60,000 plants per hectare,75,000 plants per hectare and 90,000 plants per hectare,the combination with the highest yield special combining ability was 6DH7 XJ1628.Among the main agronomic traits,ear length,ear weight and 100-grain weight,the combination with the highest specific combining ability effect under three different densities was 6DH7XJ1628.The results of comprehensive analysis showed that the combination of 6DH7 XJ1628 was the best.4.According to the results of genetic variance analysis for three densities,it can be found that some traits such as spike weight and ear diameter are mainly determined by additive gene effects,and spike weight is mainly determined by non-additive gene effects.