The Combining Ability of Maize Inbred Lines for Grain Yield and Reaction to Grey Leaf Spot Disease

Considering the potential threat of grey leaf spot (GLS) to maize production, the national maize research program of Ethiopia has been screening local and exotic maize genotypes against the disease as the commercially available and advanced inbred lines susceptible to GLS. This experiment was, therefore, conducted to investigate the general (GCA) and specific (SCA) combining ability of selected maize inbred lines for grain yield and GLS disease resistance. Eight maize inbred lines with contrasting reactions to GLS were crossed in diallel mating to generate 28 hybrids. The parents and hybrids were evaluated in randomised complete block design with three replications at Bako, Ethiopia in 2001 and 2002. Significant differences were observed among entries for disease parameters, plant height, days to maturity and grain yield. GCA and SCA effects were significant for all traits. Mean squares due to GCA were higher than that of SCA for all traits, except for grain yield, indicating the predominance of non-additive gene effect for grain yield and additive gene effect for other traits. Some inbred lines with resistance reaction have been identified. Parental lines 143-5-i and CML-387 showed a better per se performance and GCA effects while A-7016 was the worst parent for GLS disease reaction. Inbred parent 143-5-i was the best general combiner for grain yield; but a poor general combiner for plant height and days to maturity. The information from this study will be useful for the development of high-yielding and GLS disease-resistant maize varieties. Keywords: Combining Ability; Disease Resistance; Grain Yield; Grey Leaf Spot; Maize East African Journal of Sciences Vol. 2 (2) 2008: pp. 135-14