LINE x TESTER ANALYSIS FOR COMBINING ABILITY AND STANDARD HETEROSIS IN MID-ALTITUDE MAIZE (Zea mays L.) FOR GRAIN YIELD AND YIELD RELATED TRAITS AT HARO SABU, WESTERN ETHIOPIA

Abstract

The study was conducted at Haro Sabu Agricultural Research Centre (HSARC) during the 2015 main cropping season. The objectives of the study were to estimate combining ability and to identify direction and magnitude of standard heterosis in mid-altitude maize test crosses for grain yield and yield related traits. Eighteen inbred lines and four single cross testers were crossed in line x tester mating design during the 2014 main cropping season at Bako National Maize Research Center (BNMRC). The resulting 72 F1 crosses plus three standard checks (BH543, BH546 and BH547) were studied at HSARC condition. Data were collected on seventeen traits and analysis of variance was done accordingly. The mean square indicated highly significant (p<0.01) genotypic differences for all traits with the exception of shelling percentage, stand count at harvesting and common leaf rust, suggesting the presence of wide genetic variation among genotypes for most of the traits studied. The highest and significant mean performance of grain yield were recorded for L3xT1, L5xT1, L5xT2, L8xT1, L11xT3, L8xT2, L10xT2, L8xT4, L12xT1 than high yielding hybrid check BH-543 (9.36 t ha-1). GCA mean square due to lines and testers were significant for all traits except tester GCA mean square for harvesting index, anthesis silking interval, days to anthesis, days to silking and days to maturity. The mean square of SCA effect of the crosses revealed significant difference for all traits except for number of kernels per row, plant height, anthesis silking interval, days to silking, gray leaf spot and tarcicum leaf blight. Significant GCA and SCA effects were indicative of the importance of both additive and non-additive gene actions. However, the proportion of GCA sum of square was higher than SCA sum of squares for most traits, indicating the preponderance of additive gene actions in the control of most of the traits. As far as grain yield and yield related traits were concerned; this study identified good inbred lines and testers desirable GCA effects. L3, L5, L6, L8 and L11 inbred lines, and T1and T2 testers were good combiner for more than one traits. For maturity related traits, L1, L4, L14, L15, L17 and L18 were good combiners for earliness. The present study identified several elite inbred lines for grain yield and yield related traits and high yielding test crosses possessing positive and significant standard heterosis over the best check hybrid (BH543).These crosses could be recommended for release or used in maize breeding program for concerned traits after further confirmation of the result through evaluation over years and locations.