Evaluation On Breeding Potential Of 12 South American Maize Populations In Southwest China

Southwest China’s maize production area belongs to China’s main corn production area,which plays an important role in ensuring China’s corn supply.However,in recent years,Southwest China lacks local breakthrough varieties and the renewal speed of corn varieties is slow,which resulting in the stagnation of corn yield in this area.Maize DN98×Q4(Hui Min 306)and DN98×Q4-2(Yun Dan 25)perform well in Southwest China.But there is still much room for improvement in yield,plant height,ear height,water content in harvest,grain dehydration and other traits.In this experiment,12 maize populations(P1-P12)from South American were used as donor materials.DN98,Q4 and Q4-2 were used as testers.32 top-cross varieties and 40 triple cross varieties were combined by NCⅡ genetic mating design.According to the performance of 9 characters such as yield,100 grain weight,water content in harvest period,panicle length,number of rows per panicle,number of grains per row,plant height,panicle height and whole growth period,estimating the improvement potential of 12 population materials on DN98×Q4 and DN98×Q4-2.Lay the foundation for cultivating breakthrough maize varieties in Southwest China.At the same time,under the genetic background of DN98 and Q4,12 South American populations were divided to the heterosis groups,which provided a theoretical basis for maize population improvement in Southwest China.The main results are as follows:1.P1,P10 and P12 combined top-cross varieties can improve the comprehensive characters of DN98×Q4.P1 has improvement value for 100 grain weight,ear length,number of grains per row and plant height.P10 has improvement potential for yield,100 grain weight and number of rows per ear.And P12 has improvement value in 100 grain weight,number of rows per ear and plant height.P4,P7,P11 and P12 combined triple cross variety has great improvement potential for comprehensive characters of DN98×Q4.These four South American populations have improvement value for yield.Among them,P12 has the greatest potential for yield increase improvement.P7,P11 and P12 have great improvement potential in terms of water content in harvest.In addition,P12 also has improvement value in reducing plant height and panicle height and shortening growth period.The improvement direction is Q4.2.P6 and P11 combined top-cross variety can improve the comprehensive characters of DN98×Q4-2.P6 and P11 have great potential to improve the number of rows per panicle and the number of grains per row when the yield reduction is not significant,but they have little value in 100 grain weight and water content in harvest period.P3,P4 and P6 combined triple cross variety has great improvement potential for comprehensive characters of DN98×Q4-2.P6 has improvement value in the aspects of water content in harvest period,number of rows per panicle and whole growth period,and the improvement direction is DN98.Both P3 and P4 have great improvement potential in terms of water content and grain number per row.In addition,P3 can reduce the plant height and spike height.P4 can also be used to improve 100 grain weight.The improvement direction is Q4-2.3.The GCA(General Combining Ability)of P9,P10,P11 and P12 is higher in Southwest China.The effect to GCA of yield is positive,which is of great significance to increase the gene frequency related to yield in Southwest China.At the same time,the GCA of 100 grain weight,panicle length and rows per panicle of P9,P10 and P11 are positive effects.P12 is helpful to reduce the water content in harvest period and improve plant type,which can promote the enrichment of maize germplasm resources in Southwest China.4.Under the genetic background of DN98 and Q4.12 South American populations were divided into two heterosis groups according to the yield SCA(Special Combining Ability)effect.Population P1,P3,P4,P7,P10 and P12 were divided into group A.Population P2,P5,P6,P8,P9 and P11 were divided into group B.