Combining Ability of Adapted and Exotic Drought-tolerant Maize Inbred Lines Under Full Irrigation and Rainfed Conditions in Nigeria

Abstract

Adoption of improved maize (Zea mays L.) varieties in the rainforest agro-ecology of Nigeria largely depends on yielding potential and resistance to common foliar diseases. The present study aims at assessing the combining ability of a set of adapted and exotic drought-tolerant maize inbred lines under irrigated and rainfed conditions in Nigeria. Ninety-six hybrids generated using a North Carolina Design II scheme, and four checks were evaluated in a 10 × 10 triple lattice with three replications under full irrigation in the dry seasons of 2010 and 2011 and under natural disease inoculation in the rainy seasons of 2011 and 2012. Hybrids differed significantly for all measured traits. Both general combining ability (GCA) and specific combining ability (SCA) were mostly highly significant (P < 0.01) for all agronomic traits and leaf blight. Additive genetic effects were more important than non-additive genetic effects in controlling grain yield and leaf blight (GCA > 70%). EXL03, EXL06, EXL16, ADL33, and ADL47 had positive and significant female and male GCA effects for grain yield, and significant but negative GCA effects for leaf blight.