Abstract
The genetics of resistance to grey leaf spot (GLS) disease, grain yield and selected agronomic traits was studied in 42 F1 progenies from a full diallel cross among seven maize inbred lines. These 42 F1 progenies and seven parents were evaluated at three locations; Kenya Agricultural Research Institute (KARI), Kiboko, KARI Kakamega and University of Nairobi (Field station) during the period June 2006 to April 2008. The experiments were laid out in a randomized complete block design with three replicates. Combining ability analyses were conducted on the across site data of grey leaf spot disease, grain yield and selected agronomic traits using Griffing’s method one, model one in the SAS program. Additive gene action played a greater role than non-additive gene action in the inheritance of resistance to grey leaf spot disease whereas the non additive effects were more important in the inheritance of grain yield. Reciprocal effects were not significant for GLS disease resistance and grain yield indicating absence of maternal effects for these traits. The inbred lines, CML 384 and CML 373 were the best combiners for grain yield with general combining ability (GCA) effects of 0.79 and 0.56 respectively while TZMI 711 and CML 373 were the best combiners for GLS resistance with highest negative values for GCA of -0.51 and -0.398, respectively. The local maize breeders could now incorporate the genes for GLS resistance in CML 373 and TZMI 711 and the grain yield genes in CML 384 into elite lines using recurrent and backcross methods, respectively in order to increase maize production and productivity in Kenya. Key words: Maize, Zea mays, grey leaf spot, grain yield, combining ability
Highlights
Maize is an important staple crop providing 50, 30 and 15% of calories in diets in Southern Africa; East Africa and Western and Central Africa, respectively (Beyene et al, 2012)
The identification of single crosses with high and positive general combining ability (GCA) effects for grain yield suggested that potential parents could be exploited in the development of various hybrids, including three-way, double-cross and double top cross hybrids
Combining ability analyses were conducted using Griffing’s (1956) method I model I to obtain the estimates of the GCA and specific combining ability (SCA) effects using the ProcGLM model of the SAS program (SAS, 1996)
Summary
Maize is an important staple crop providing 50, 30 and 15% of calories in diets in Southern Africa; East Africa and Western and Central Africa, respectively (Beyene et al, 2012). The combining ability could help to provide inference in the selection of elite inbred lines (Legesse et al, 2009a) in order to establish the type of gene action which control the grey leaf spot resistance (Legesse et al, 2009b). Combining ability comprises both general combining ability (GCA) and specific combining ability (SCA). The identification of single crosses with high and positive general combining ability (GCA) effects for grain yield suggested that potential parents could be exploited in the development of various hybrids, including three-way, double-cross and double top cross hybrids. This study was undertaken to (a) to estimate GCA effects for grain yield and grey leaf spot among the inbred lines and (b) to estimate SCA effects and identify best hybrid combinations among the inbred lines
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