Evaluation Of Combining Ability Of Maize Inbred Lines Based On The Selection Of Xiashan A And Shan B Groups In Different Locations

During maize breeding process,the key cycle was combination,the difficult point was selecting inbreds,and the core was the problem of combining ability.Among them,the combining ability is one of the important parameters for evaluating maize inbred lines,and evaluating the combining ability of inbred lines is a very important part in maize breeding.In this experiment,we evaluated new inbred lines selected from Shaan A and Shaan B population in 2019 and 2020 year based on NC-II genetic mating design.In 2019,the combining ability of eight tested lines were evaluated by crossing with KA105 and 91227 under two plant densities at seven locations;in 2020,the combining ability of 34 new tested lines were evaluated by crossing with eight test lines including KA105,91227,KB208 etc.at four locations.There were conclusions as followings:First,the general combining ability(GCA)of maize inbred lines shows great variants between different locations.Along with the location number increased,the inbreds with stable positive effective GCA were less.It suggested we can increase the validity of identify the GCA by increasing the experiment locations.Second,increasing plant density can improve the effectiveness of evaluation for the GCA.Among the five inbred lines,which showed positive effects for GCA under the condition of regional test density,four of them still showed positive effects under the density with 100 plants/hm2 exceeding region test density,namely: 2017KB100,2017KB118,2017KB562,2017KB70.Third,we selected inbred lines with higher GCA in this experiments.In 2019,five maize inbred lines including 2017KB118,2017KB562,2017KB100,2017KB82 and2017KB70,generally perform higher GCA in all locations under regional test density.At a density with 100 plants/hm2 exceeding region test density,three inbred lines including2017KB100,2017KB118 and 2017KB66 showed higher GCA in all locations.In 2020,GCA of 2018KA-79-2,2018KB-74-3,2018KB-210-1 and 2018KB-244-2 is high and the stability is good.Four,good combinations were selected through the analysis of the special combining ability(SCA)and yield stability of the hybrid combination.In 2019,SCA and yield stability of the combination KA105×2017KB82 performed better under the regional test density,and SCA and yield stability of KA105×2017KB66 performed better under the density with 100 plants/hm2 exceeding region test density.In 2020,SCA and yield stability of combinations 2018KA-66-2× KB082,2018 KB-209-3× KA327,2018KB-210-1×KA105,2018KA-79-2× KB082 and 2018KA-50× KB208 performed better.In summary,the general combining ability of maize inbred lines in different locations shows large differences,and shows large differences between different densities.Increasing the number of test points and increasing the test density are helpful for the selection of maize breeding.Inbred lines with excellent performance.At the same time,it is helpful to select hybrid combinations with high special combining ability and good yield and stability in multiple environments.