Genotype by environment interaction of seed and oil yield in vernonia (Vernonia galamensis variety ethiopica)

Vernonia (Vernonia galamensis variety ethiopica) is a potentially novel renewable source of natural epoxy oil. The objective of this study was to determine the genotype by environment interaction and to identify superior and stable genotypes of vernonia with high seed and oil yield. Field experiments were conducted during 2006, 2007 and 2008 at two localities namely, Gabaza and Syferkuil. Ten selected genotypes of vernonia were evaluated for seed yield, oil content and oil yield using the randomized complete block design with three replications. Significant interactions (P ≤ 0.05) were detected among genotype by location for seed yield, oil content, oil yield and genotype by year for seed and oil yield. Genotype Vge-18 had the highest seed yield ranging between 3095 and 3337 kg/ha followed by Vge-17 yielding 3006–3137 kg/ha at Gabaza. These genotypes were also the best performers at Syferkuil where Vge-17 yielded 2915–3217 kg/ha followed by Vge-18 with 2819–3152 kg/ha. The superiority statistics allocated Vge-17 and Vge-18 as best yielding and stable genotypes. In both locations Vge-4 had increased seed oil contents at 43% (Gabaza) and 35% (Syferkuil). Other promising genotypes with high seed oil content were Vge-33 at Gabaza (40–43%) and Vge-3 at Syferkuil (34–35%). Genotypes with the highest oil yields were found to be Vge-18 (1117–1370 kg/ha) at Gabaza and Vge-4 with yields of 885–922 kg/ha at Syferkuil. Overall, Vge-17 and Vge-18 were identified as having the highest seed yield, while Vge-4 and Vge-3 yielded the highest seed oil content with average stability. These genotypes could be used for direct large scale production or strategic breeding of vernonia in these or similar environments.

Research highlights
► We examined genotype by environment interaction of vernonia for seed and oil yield using 10 genotypes, over three years and at two localities.
► Significant interaction (P < 0.05) and rank differences detected among genotype by location and genotype by year for seed and oil yield in vernonia.
► Two genotypes Vge-17 and Vge-18 were identified as having the highest seed yield, while Vge-4 and Vge-3 yielded the highest seed oil content with average stability.
► The selected genotypes could be used for direct large scale production or strategic breeding of vernonia in the test or similar environments.