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ORIGINAL RESEARCH article

Front. Energy Res.
Sec. Bioenergy and Biofuels
Volume 12 - 2024 | doi: 10.3389/fenrg.2024.1425213
This article is part of the Research Topic Opportunities and Barriers in Anaerobic Digestion of Biomass View all 3 articles

Survival of plant seeds in digestate storage - with and without prior anaerobic digestion

Provisionally accepted
Juliane Hahn Juliane Hahn 1,2*Vincent Plogsties Vincent Plogsties 2Bärbel Gerowitt Bärbel Gerowitt 1Monika Heiermann Monika Heiermann 2
  • 1 University of Rostock, Rostock, Germany
  • 2 Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), Potsdam, Brandenburg, Germany

The final, formatted version of the article will be published soon.

    Plant seeds from weeds and energy crops have the potential to survive anaerobic digestion (AD). Species able to form physically dormant, i.e., hardseeded (HS) seeds seem particularly resistant. However, it is not yet known to what extent the storage of the digestate after AD affects seed viability.Seed survival of five HS and six non-HS (NHS) species was investigated in three combinations of digestate storage (DS) and AD. First, untreated seeds were exposed to DS for maximum 12 weeks. To simulate short-circuited AD (ADshort) in biogas reactors, seeds were second subjected to labscale AD for one day before DS. Third, seeds of six species were exposed to full-scale AD (ADfull) followed by DS. Seed viability was determined using a combination of germination tests and tetrazolium staining. Viability was modeled as a function of exposure time.Seed viability was affected by DS, AD and AD+DS, but responses varied greatly between species and treatments. With increasing exposure time, viability decreased after a lag-phase, remained stable or even increased. The NHS species Cichorium intybus, Daucus carota, Echium vulgare, and Verbascum thapsus were most susceptible, with seed-killing close to 100% if DS was involved. The HS species Malva sylvestris, Melilotus albus and Melilotus officinalis were most resistant. They survived all treatments and were alive after 35 days of ADfull plus 3 months of DS. The resistance potential of the HS species Abutilon theophrasti and Malva alcea and of the NHS species Chenopodium album and two tomato varieties was intermediate. None of them survived ADfull+DS, but except A. theophrasti they were viable after ADshort+DS. With few exceptions, seed-killing by AD+DS was higher than that by AD alone.In conclusion, DS and AD+DS have the potential to reduce seed viability, but do not completely inactivate all species. Therefore, digestate can be contaminated with viable seeds and may lead to the spread of weeds, especially after a short-circuited AD. In order to ensure the sustainable use of digestates in terms of weeds, we recommend to investigate the factors contributing to seed inactivation and the quantity of seed introduced to AD.

    Keywords: Exposure time, fertilizer, physical dormancy, Short-circuiting, seed inactivation, sustainability, temperature, weed

    Received: 29 Apr 2024; Accepted: 04 Sep 2024.

    Copyright: © 2024 Hahn, Plogsties, Gerowitt and Heiermann. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

    * Correspondence: Juliane Hahn, University of Rostock, Rostock, Germany

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