Imaging the germination behaviour of sugar beet (Beta vulgaris) seed enhancement technologies using X-ray computed tomography

Blunk, Sebastian (2019) Imaging the germination behaviour of sugar beet (Beta vulgaris) seed enhancement technologies using X-ray computed tomography. PhD thesis, University of Nottingham.

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Sustaining a growing population is one of the great challenges of humanity and a key part of several of the most recent sustainable development goals (Transforming our World: the 2030 Agenda for Sustainable Development, United Nations General Assembly 2015). With rising environmental challenges, improved application in agricultural engineering is growing more and more important. Seed enhancement techniques, such as the application of materials to alter their shape to improve ease of planting and protect against pests as well as pre-germination under limited water availability has been used for several decades to improve crop establishment and support yields especially under severe environmental conditions.

This study aims to understand the effect of the application of seed enhancement technologies on belowground interactions with the soil matrix using X-ray Computed Tomography (X-ray CT) as a tool for non-destructive 4D imaging. The successful application of X-ray CT enabled the in-situ comparison of different seed treatments and thereby indicating negative impacts of applying active ingredients directly on the fruit. However, this can be overcome by using pelleting materials which increase the distance of the active ingredients to the embryo. Pre-germination treatments showed advantages in the volume of soil exploration by the roots independent of physical seed enhancements allowing nutrient mining in a larger volume. The development of a method to image seed-soil contact for the first time has helped to gain new insights in how seeds initiate germination. A significant advantage of spherical shaped seeds (commercial product) compared to the untreated irregular shaped seed in terms of contact area was revealed, however, a high variability in the field across multiple soil textures and management techniques indicated low control by farmers over this factor. This was partly attributed to limited accuracy in seed placement to the intended depth in the seedbed. Ultimately, it was shown that the fruit orientation had significant effects on germination speed and also on the swelling behaviour of the individual fruits. Furthermore, the selection of pelleting materials has strong effects on germination speed under varying water conditions which correlates with the water holding capacity and conductivity of the material. It was also found that water relations of pelleting materials change during the pelleting process influencing ultimate water potential. The understanding of morphological features within the fruit was advanced using X-ray CT and Magnetic Resonance Imaging (MRI) revealing a novel fruit internal water distribution pathway.

This work helped to advance the understanding of seed enhancement technologies for the seed industry in multiple regards: The selected active ingredient within the seed coat should exhibit a low water solubility to not penetrate the pellet material and thereby reducing germination speed. Pellet materials were found to be beneficial when exhibiting low swelling but high water dispersion capabilities. Finally, fruit rubbing for improved performance during the pelleting process and reduction of germination inhibitors should be limited to not disturb water distribution channels within the pericarp.

Item Type: Thesis (University of Nottingham only) (PhD)
Supervisors: Mooney, Sacha J.
Sturrock, Craig J.
de Heer, Martine I.
Hoffer, Jeroen
Malik, Ali Hafeez
Keywords: Seed enhancement; Soil matrix; Pelleting materials; Seed-soil contact; Water distribution channels
Subjects: S Agriculture > SB Plant culture
Faculties/Schools: UK Campuses > Faculty of Science > School of Biosciences
Item ID: 56693
Depositing User: Blunk, Sebastian
Date Deposited: 26 Apr 2022 08:45
Last Modified: 26 Apr 2022 08:46

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