Genetic Variation and Path Coefficient Analysis of Introgressed Maize Inbred Lines for Economic Traits

Knowledge of the effects of introgressing temperate maize germplasm in tropical elite inbred lines on genetic variation and relationship between grain yield and its components is limited. In this study, the objective was to evaluate introgressed maize inbred lines for selected economic traits. Field evaluation was carried out on 122 inbred lines comprising sets of introgressed lines from three selection environments, parental inbred lines and two common checks. Genetic variation was significant (P < 0.05) for all the major economic traits among inbred lines within and across sets. Heritability estimates ranged from low (0.21%) to high (91%) for stalk lodging and silking days, respectively. Comparison of means of inbred lines sets illustrated that environmental effect had influence on grain yield of introgressed lines. Grain yield and ear prolificacy performance across sets also illustrated that introgression of temperate germplasm in tropical elite inbred lines was effective. Spearman’s rank correlation analysis on grain yield and ear prolificacy highlighted correlation between selection environments. Correlation among traits demonstrated that grain yield had significant (P < 0.05) positive correlation with plant and ear aspects, plant height, root and stalk lodging, ear prolificacy and grain moisture content at harvest. Further, decomposing of correlation using path coefficient analysis showed significant (P < 0.05), and moderate direct effects of ear prolificacy and plant height on grain yield; indicating that these traits had the highest contribution towards grain yield. Generally indirect effects of secondary traits on grain yield potential of inbred lines was negligible. Therefore, direct selection of plant height and ear prolificacy will be emphasised during introgression of temperate germplasm in tropical elite inbred lines.