| dc.description.abstract | Analysis of combining ability plays an important role in identifying elite parents and crosses which can give best combinations based on the performances of their offspring. Hybrid variety production requires broad genetic base among the germplasm as materials to be used as parents because their increase heterosis which can be exploited. There is little knowledge on general and specific combining ability of inbred lines developed by Maseno University maize breeding programme which lead to development of inferior parent and crosses, also knowledge on inbred lines make breeding process more effective as save breeding cost and time. The general objective of this study was to identify parents and crosses with desirable combining ability in order to contribute to increased grain yield. The specific objectives were to analyze general and specific combining ability among selected maize inbred lines and their hybrids for grain yield and yield components among selected inbred lines and their hybrids, assessment of heterosis for F1 hybrids involving selected inbred lines of maize. The study was carried out in the Maseno University demonstration farm between 2019-2021 The study involved making crosses among nine inbred lines in half diallel method II model I to obtain 36 F1 hybrids and evaluating them. The nine inbred lines and their 36 hybrids were planted in randomized complete block design with three replications. The crosses were used to estimate general combining ability (GCA) and specific combining ability (SCA) effects on grain weight, yield related traits and assess heterosis for the F1 hybrids in order to select suitable parents for hybridization and identify superior and promising hybrids. The eight traits measured included days to 50% flowering, days to 50% silking, plant height, ear height, cob length, and cob width, number of rows per cob and grain weight. The data were subjected to Analysis of variance (ANOVA) and means separated using the Least Significant difference at p< 0.05. Mean squares for genotype, SCA and GCA were found to be significantly different. Inbred lines F620R, Cy441/2 and RC 9 were found to be good general combiners for most of the traits hence they can be useful for hybrids development. Crosses F620R X Ex 389, Ex614P X F620R, Ex614P X F-white, F-white X Cy441/2 and Cy441/2 X RC 9 had high positive and significant SCA for grain weight and most of yield related traits hence can be used to develop superior hybrids. Specific combining ability based on yield was used to indicate heterotic grouping of crosses. GCA: SCA ratio were high for days to 50% flowering, days to 50% silking, plant height and number of rows per cob while it was low for ear height, cob width, cob length and grain weight. This shows the importance of both GCA and SCA in inheritance of yield and yield related traits. Among 36 F1s all crosses exhibited high heterosis for grain yield except Ex 614P X Ex bear, Ex 614P X Ex 389, Ex 389 X Bear614 and F620R X Cy441/2 which exhibited low heterosis values. Identified parents and crosses with high GCA and low SCA values could be used in development of superior hybrids and synthetic varieties. There was significance difference in GCA, SCA and heterosis among genotypes hence they is genetic difference which can be exploited further. | en_US |
