Diallel analysis of maize inbred lines for agronomic traits in nitrogen stress and optimal conditions

D J Ogunniyan,O A Talabi,S A Olakojo,D K Ojo

doi:10.4314/gjas.v54i1.2

Abstract

Increasing demand, soil cultivation pressure and adverse climate change effects necessitated maize production in nitrogen stress soils. This study examined the general combining ability (GCA) of 12 maize inbreds and specific combining ability of their crosses for agronomic traits under varied nitrogen conditions. GCA accounted for 53% of the variation for grain yield (GY) under stress and 40% under optimal condition. GCA contributed over 59% for days to anthesis (DTA) and days to silking (DTS), anthesis-silking-interval (ASI) and ear aspect (EASP) under both conditions. BD74-165 and BD74-161 had positive significant GCA for GY under stress with TZEI12 under optimal and BD74-222 under both conditions. TZEI13 and TZEI16 had positive significant GCA for DTA and ASI under stress, and TZEI12, TZEI11 and BD74-161 under optimal. Additive genes control DTA, DTS and PH; non-additive genes were responsible for ASI, PASP and EASP while both additive and non-additive genes governed inheritance of GY, EH and leaf-senescence (SEN) under stress. Inheritance of GY, ASI, PH, PASP and EASP were due to non-additive genes; DTA and DTS to additive genes while additive and non-additive genes control EH and SEN under optimal condition. Inbreds with significant GCA can be parents for GY improvement under respective conditions. Keywords: Combining ability; diallel; low nitrogen; maize lines; stress tolerance

Highlights

Maize is well adapted to West and Central Africa (Ajala et al, 2007), but its mean grain yields range between 1.0 and 2.0 t ha-1 compared to about 8.6 t ha-1 in the temperate countries (FAOSTAT, 2015)
Analysis of variance of the agronomic traits of the hybrids under varied N conditions Environmental effects were highly significant for all the traits (P
Significant general combining ability (GCA) for grain yield (GY) ranged from -1001.0 in TZEI11 to 491.4 in BD74161 under N stress

Summary

Introduction

Maize is well adapted to West and Central Africa (Ajala et al, 2007), but its mean grain yields range between 1.0 and 2.0 t ha-1 compared to about 8.6 t ha-1 in the temperate countries (FAOSTAT, 2015). The low grain yield in Africa is partly ascribed to poor soil fertility status and management (Azeez & Adetunji, 2007). Nutrients leaching and low level of soil organic matter have made N insufficiency a major constraint to sustainable smallholder maize production in Africa (Badu-Apraku et al, 2010; Ismaila et al, 2010). The annual loss of maize yield due to N stress varies from 10 to 50% (Wolfe et al, 1988). Maize performance varies within varieties across soil fertility levels from location to location and N use efficiency (Liang et al, 2005), because variation exists in gene expression of maize for low N tolerance. Nitrogen is a major nutrient responsible for

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