Genotype by environment interaction for oil quality components in olive tree

Olive oil is highly valued by its nutritious and healthy function mainly due to its chemical composition. Oil chemical components are highly influenced by the cultivar and the environment, resulting in some cases in levels out of the limits set by the International Olive Council. In the present research, we used a multi-environment trial with five different agro-climatic conditions of Andalusia to evaluate how genetic and environmental factors and their interactions influence some of the most important olive quality components. Most of variation for olive components according to ANOVA was attributed to genetic effect, which was supported using principal component analysis and linear discriminant analysis. For the fatty acids, ‘Arbequina’ showed oils with the highest C16:0 and C18:2 values, and the lowest C18:1. Contrarily, an advanced breeding selection, Selection 2, and ‘Picual’ showed high C18:1 and low C16:0 and C18:2. The minor components varied depending of the genotype, underlining very high squalene values in ‘Carrasqueño’. Even so, the environment and the G x E interactions also resulted highly significant, with some genotype-environment combination unfavourable for oil composition as ‘Arbequina’-Gibraleón. The significant interactions were analysed separately by additive main effects and multiplication interaction to identify the most stable genotypes and adaptations to specific environments. For instance, ‘Arbequina’ showed low stability for C18:1 and C18:2, but very high stability for total tocopherol content and squalene content. These results underline the relevance of using multi-environment trials for adequate characterization of genotypes for oil components.