Study On HETEROSIS OF IMPROVED MAIZE GERMPLASM Lines From BSSS Group In USA And Inbred Lines From China

In this experiment,7 inbred lines of BSSS group in the United States and 6 inbred lines of domestic Germplasm with different blood relationship were selected to analyze the genetic diversity of 13 parents by SSR molecular marker technology,and the genetic distance was determined from the molecular level for cluster analysis,Based on the analysis of the Heterosis and combining ability of BSSS,we selected 42 crosses with strong combining ability.1.Cluster analysisCluster analysis showed that 13 inbred lines could be divided into four groups.The first group was dan349 and S121,which belonged to lvdahonggu group of domestic germplasm;the second group was ji853 and chang7-2,which belonged to Tangsipingtou group of domestic germplasm;the third group was ftll and ft17,which belonged to tropical blood germplasm;the fourth group was ji853 and chang7-2,which belonged to Tangsipingtou group of domestic germplasm BSSS group is the main group in the United States,and there are 7 improved maize inbred lines of ph6wc.This group can also be divided into three subgroups,ft145,ft126 and ft139,which are backcrossed by ph6wc;ft182,ft320 and ft207 are obtained by crossing ph6wc with ph288 and other inbred lines;ft319 has a slightly distant genetic relationship with ph6wc.2.Analysis of general combining abilityConsidering all traits,there is no parent whose GCA is positive effect,among which 13 traits of dan340 are positive effect,15 traits of ft139 are positive effect,14 traits of ft207 are positive effect.Considering all traits,these three inbred lines have many excellent genes,which can be further studied and utilized;other inbred lines have different defects Further genetic improvement is needed.3.Analysis of special combining abilityFrom the perspective of disease resistance,ft17×ft319 has strong resistance to big leaf spot and stem rot;ji853×ft207 has fast dehydration and low water content,which is suitable for mechanized harvest;ft11×ft320 and ji853×ft182 have certain advantages in yield per mu,and ft11×ft320 has better ear type,which has advantages in bald tip length,row number,row number,100 grain weight,ear length,grain depth and ear weight Advantages.4.Through cluster analysis of inbred lines,the genetic distance was calculated,and then the combining ability was determined to screen the combination with larger genetic distance and high combining ability.