Correlation and sequential path analysis of oil yield and related characteristics in camelina under seasonal variations

The objectives of the current study were to determine the usefulness of sequential path analysis in camelina to obtain information about the relationship between yield and yield components and to evaluate their relative importance in camelina oil yield under summer and winter cultivation. A split-plot design, with two varieties as the main plot and four sowing times as the subplot, was carried out over two growing seasons (2017–2019) in Samsun, Turkey. Sequential path analysis revealed that, as first-order predictors, grain yield and oil content displayed the most significant and positive direct effects on oil yield in both summer and winter cultivation. The sequential path analysis of second-order variables over the first-order variable revealed that seed number per pod and pod number explained approximately 90% of the variation of the grain yield in summer cultivation and branch number explained approximately 67% of the variation grain yield in winter cultivation. These results indicated that grain yield, as a main predictor of oil yield, had different pathways to affect oil yield in the summer and winter seasons. A higher magnitude of seed number per pod compared to pod number in this study indicated that selecting for higher grain yield can be done indirectly using plants with lower pod number and higher seed number per pod in the summer season. Moreover, branch number was the only trait that had a direct negative effect on grain yield in the winter season, indicating that plants with lower branch number should be selected for higher grain yield. Different environmental factors, including the seasonal cultivation of camelina in this study, were found to be a key factor in improving oil yield and, hence, should be considered as criteria indices in camelina breeding programs in the future.