Genetic analysis of grain yield and other traits of early maturing maize inbreds under drought and wellwatered conditions

Abstract

Maize (Zea mays L.) is an important staple food crop in West and Central Africa(WCA). However, its production is constrained by drought. Knowledge andunderstanding of the genetics of hybrid performance under drought is invaluablein designing breeding strategies for improving maize yield. One hundred and fiftyhybrids obtained by crossing 30 inbreds in sets using the North Carolina DesignII plus six checks were evaluated under drought and well-watered conditions for2 years at three locations in Nigeria. The objectives of the studies were to (i)determine the mode of gene action controlling grain yield and other importantagronomic traits of selected early inbred lines, (ii) examine the relationshipbetween per se performance of inbreds and their hybrids and (iii) identify appropriatetesters for maize breeding programmes in WCA. General combining ability(GCA) and specific combining ability (SCA) mean squares were significant(P < 0.01) for grain yield and other traits under the research environments. TheGCA accounted for 64.5 % and 62.3 % of the total variation for grain yield underdrought and well-watered conditions, indicating that additive gene action largelycontrolled the inheritance of grain yield of the hybrids. Narrow-sense heritabilitywas 67 % for grain yield under drought and 49 % under well-watered conditions.The correlations between traits of early-maturing parental lines and their hybridswere significant (P < 0.01) under drought, well-watered and across environments.Mid-parent and better-parent heterosis for grain yield were 45.3 % and18.4 % under drought stress and 111.9 % and 102.6 % under well-watered conditions.Inbreds TZEI 31, TZEI 17, TZEI 129 and TZEI 157 were identified as thebest testers. Drought-tolerant hybrids with superior performance under stressand non-stress conditions could be obtained through the accumulation offavourable alleles for drought tolerance in both parental lines