The role of seed structure on hemp germination: A study based on X-ray microtomography and 3D image analysis

Industrial hemp ( Cannabis sativa L.) has recently been reassessed in many countries for its multifunctionality and sustainability being used in several production sectors, including food, construction, textiles, bio-composites, and cosmetics. Nevertheless, the seeds of this species present several critical issues, such as low germination rates and high variability in the quality of seed lots available on the market. 3D X-ray imaging is considered a valuable tool for the classification of seeds based on their internal morphological features. The aim of this work was to explore the role of the internal seed structure on hemp germination. X-ray microtomography and 3D image analysis combined to multivariate discriminant analysis was applied on seeds of four different hemp varieties. Overall considered the three-dimensional morphometric characterisation of hemp seed internal structure showed a good potential to discriminate normal and ungerminated outcomes, while the abnormal outcomes resulted misclassified. The Solidity and Fractal dimension of the seed tissue showed to be the most discriminant morphometric parameters between normal seedlings and ungerminated seeds. An X-ray exposure side experiment allowed to exclude effects on hemp seed germination results due to the used X-ray imaging approach. Our work showed overall the contribution of X-ray microtomographic imaging combined to multivariate discriminant analysis to improve the knowledge of the relationship between 3D internal morphology of the hemp seeds and their germination potential.