Combining Ability And Correlation Analysis Of Main Agronomic Traits Of 19 Maize Inbred Lines

The excellent performance of maize hybrids depends on parental inbred lines,and parental selection and matching is one of the key factors for the success or failure of hybrid breeding.Combining ability is the core of inbred line breeding and hybrid combination,and it is one of the key indicators for selecting parents.In this study,we used 19 maize inbred lines newly bred by our research group as materials,and used incomplete diallel cross design to construct 78 hybrid combinations.In the experiment,we measured plant height,ear height,stem diameter,tassel length,tassel branch number,leaf angle,ear length,ear diameter,ear row number,kernel per row and sterile length.The general combining ability(GCA)and special combining ability(SCA),genetic parameter estimation and correlation analysis of these traits were carried out.The analysis and evaluation of inbred lines provide the basis for the utilization of inbred lines in breeding.The main results are as follows:1.According to the analysis of GCA of plant type and ear characters,the main characters of inbred lines 003、006、009、055、097、100、117、120、133、167、565、566、567、572 and 579 were excellent.For example,the GCA values of plant height and ear height of inbred line 003 were-3.54 and-5.63.Using inbred line 003 as parent,the plant height and ear height of combination could be effectively reduced.The GCA values of tassel length,branch number and leaf angle of inbred line 117 were-0.07,-10.85 and-5.24,respectively.The GCA values of tassel branch number and leaf angle on ear of inbred line 167 were-7.76,-1.85 and-7.13,respectively.The GCA values of male panicle branch number and leaf angle of inbred line566 were-11.54,-12.94 and-18.30,respectively.The GCA values of tassel length,branch number and leaf angle of inbred line 576 were-2.57,-29.66 and-5.36,respectively.The tassel length,branch number and leaf angle of inbred lines 117,167,566 and 576 were negative and small.Using these four inbred lines to make hybrids,we can effectively reduce the size of tassel and obtain the varieties with compact plant type and upward flush.The GCA values of ear length and grain number per row of inbred line 055 were 8.06 and 0.21,respectively.The GCA values of ear length and grain number per row of inbred line 572 were6.77 and 3.15,respectively.Using inbred lines 055 and 572 as parents,it is easy to get the combination with longer ear and more grains per row.2.According to the analysis of special combining ability of plant type characters and ear characters of each hybrid combination,the hybrid combination 006×565、012×566、012×579、053×567、097×565、100×565、117×566、117×576、133×579、167×576、188×572 had good agronomic characters,which could be further tested;The plant height,ear height,tassel length,branch number of tassel and leaf angle on ear of 117×576 were negative,and the stem diameter showed positive effect.The combination showed compact plant type,moderate plant height and ear position.The special combining ability(SCA)effect value of 100×565 was higher than others in panicle length,panicle diameter,rows per panicle and grains per row.The SCA effect value of sterile length was negative,and the comprehensive characters of this combination were outstanding.3.Through the analysis of genetic parameters of each character,it is found that the variance of the general combining ability of six main agronomic characters,including plant height,spike height,stem diameter,tassel length,branch number of male spike and angle between leaves on the spike,is greater than that of special combining ability,which indicates that the heterosis of the 5 traits is mainly additive effect.The narrow heritability of plant height and branch number of male panicle was more than 50%,which should be selected early.The narrow heritability of high spike height,stem thickness,tassel length and leaf angle on the ear is less than 50%,which should be selected in higher generation.The narrow heritability of five characters,such as ear length,ear diameter,row number,grain number and sterile length,is less than50%,which is not suitable for early generation selection,and should be selected in the high generation when characters of inbred lines are stable.4.Through the correlation analysis of main agronomic characters,plant height and ear height,ear and tassel branch number,ear length and grain number row very significant positive correlation.There were significant positive correlations between spike length and spike length,spike length and spike row number,and spike diameter and spike row number.Plant height and tassel branch,ear height and male spike length,ear height and ear rows were extremely significant negative correlation.Ear row number and row grain number and grain number and bald tip length was significantly negative correlation.The utilization value of the selected inbred lines in maize breeding was analyzed and evaluated,which provided theoretical basis for the selection of inbred lines and the combination of hybrid.