Mid-parent and Better Parent Heterosis Study on Highland Quality Protein Maize Hybrids in Ethiopia

Determination of heterosis in maize hybrids is necessary for the identification of superior F1 hybrids for breeding programs. Therefore, this study was conducted to estimate the amount of mid parent (MPH) and better parent heterosis (BPH) for grain yield, yield-related, agronomic, and morphological traits. Hybrid development from fixed inbred lines is one of the strategies for the improvement of maize production. The national average maize yield in Ethiopia is low and thus, selection of promising germplasm, knowledge of combining ability, and heterotic grouping are prerequisites to developing high-yielding maize varieties. Forty-two Quality Protein Maize (QPM) crosses (21 inbred lines each crossed with two testers) along with three popular standard hybrids were evaluated in two replications using alpha lattice during the 2017 cropping season at Ambo and, Arsi-Negele. Parental line trials consisting of 21 lines, two testers, and one conventional maize (CM) parent check (FS67) were established in two replications laid out using RCBD side by side with the hybrid trials at Ambo and Arsi-Negele. At Ambo, almost all crosses showed positive and significant BPH except three crosses (L1xT1, L4xT1, and L13xT1). The maximum BPH (276.2%) was obtained from L17xT2. Similarly, at Arsi-Negele, most of the crosses had positive and significant BPH except for five crosses for BPH which are showing negative heterosis. The highest BPH was obtained from L10xT2 at Arsi-Negele. Generally, the high yielding crosses had reasonable BPH. Based on the result promising crosses and lines were identified. Some of the crosses showed good performance in terms of heterosis against the mid parent and better parent: L17xT2 (329.88% MPH, 276.18% BPH), L3xT2(320.05% MPH, 273.91%BPH), and L19xT2(2802.57% MPH, 247.31% BPH) at Ambo, whereas at Arsi-Negele L10xT2 (128.38% MPH, 111.27%BPH) and L11xT2(115.33% MPH, 98.00% BPH) showed the higher heterosis compared with the mid parent and better parent. Crosses that showed best yield performance were: L8xT2, L7xT1, L8xT1, L19xT1, L6xT2, and L18xT1. These crosses should be reconsidered for further evaluation and possible release.