EVALUATION OF YELLOW MAIZE (Zea mays L) INBRED LINES’ PERFORMANCE AND COMBINING ABILITY USING LINE BY TESTER ANALYSIS IN WESTERN KENYA

Abstract

There is need to continuously develop and deploy highly adaptable and productive maize hybrid varieties for use by farmers against the greatly dynamic biotic and abiotic stresses that face production of this crop in the country. The objective of this study was to estimate the hybrid performance and the combining abilities of yellow maize inbred lines and their testcrosses for grain yield and yield-related traits across three locations. Sixty-five yellow maize inbred lines were crossed to two-line testers; Cimmyt maize lines (CML) 486 (Tester A) and 451 (Tester B) using a line by tester design. Resultant a hundred and thirty F1 testcrosses with three check varieties were evaluated on three locations in western Kenya using a 7×19 alpha lattice with two replications. Data on grain yield and yield-related traits was collected. Means and variance components on hybrid performance were computed in META-R version VI and combining ability analysis done using Restricted maximum likelihood (REML). Grain yield means ranged between 12.4T/Ha and 2.8T/Ha with testcross L45×TA producing the highest grain yield mean across sites. High heritability (>60%) was recorded for grain yield and other yield-related traits except for northern leaf blight which was moderate. All yield-related traits in the study except northern leaf blight had significant phenotypic correlations with grain yield. Ear height had the highest positive correlation at 0.7(P<0.001). Across sites Analysis of Variance (ANOVA) revealed highly significant (p<0.001) mean squares for sites, hybrids, line general combining ability (GCA) line GCA by site, hybrid by site, specific combining ability (SCA) as well as SCA by site. L45 had the highest positive GCA for grain yield at 2.7 (p<0.05). L23, L65, L29 and L25 crossed with tester A showed positive significant SCA estimates for grain yield whereas L36×TA had a negative but significant SCA for grain yield at -1.9 (p<0.05). Based on SCA estimates with the testers, the inbred lines grouped into two heterotic groups A and B with 60% and 38.5% of the inbred lines respectively. L45 and other 33 lines that had positive GCA for grain yield could be exploited in the development of high yielding yellow maize hybrids. Testcrosses L45xTA, L47xTA and L35xTB showing equivalent or better performance to the mean of the checks have potential for further evaluation and consideration for release as adaptable and stable superior yielding yellow maize single cross hybrids.