Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas Reactors
The use of wildflower species as biogas feedstock carries the risk that their seeds survive anaerobic digestion (AD) and cause weed problems if spread with the digestate. Risk factors for seed survival in AD include low temperature, short exposure and hardseededness (HS). However, it is not possible...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2022-07-01
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| Series: | Frontiers in Plant Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fpls.2022.942346/full |
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| author | Juliane Hahn Paula R. Westerman Friederike de Mol Monika Heiermann Bärbel Gerowitt |
| author_facet | Juliane Hahn Paula R. Westerman Friederike de Mol Monika Heiermann Bärbel Gerowitt |
| author_sort | Juliane Hahn |
| collection | DOAJ |
| description | The use of wildflower species as biogas feedstock carries the risk that their seeds survive anaerobic digestion (AD) and cause weed problems if spread with the digestate. Risk factors for seed survival in AD include low temperature, short exposure and hardseededness (HS). However, it is not possible to predict how AD will affect seed viability of previously unstudied species. In laboratory-scale reactors, we exposed seeds of eight species from a mixture of flowering wild plants intended as biogas feedstock and three reference species to AD at two mesophilic temperatures. Half of the species were HS, the other was non-HS (NHS). Viability was determined using a combination of tetrazolium and germination tests. Viability and germinability were modeled as functions of exposure time using a dose-response approach. Responses to AD varied considerably among species, and none of the considered influencing factors (time, temperature, HS) had a consistent effect. Seed lots of a species differed in inactivation times and seed-killing efficacy. The HS species Melilotus officinalis, Melilotus albus, and Malva sylvestris were particularly AD-resistant. They were the only ones that exhibited biphasic viability curves and tended to survive and germinate more at 42°C than at 35°C. Viability of the remaining species declined in a sigmoidal curve. Most NHS species were inactivated within a few days (Cichorium intybus, Daucus carota, Echium vulgare, and Verbascum thapsus), while HS species survived longer (Malva alcea). AD stimulated germination in the HS species A. theophrasti and its AD-resistance overlapped with that of the most resistant NHS species, C. album and tomato. In all seed lots, germinability was lost faster than viability, implying that mainly dormant seeds survived. After the maximum exposure time of 36 days, seeds of HS species and Chenopodium album were still viable. We concluded that viability responses to mesophilic AD were determined by the interplay of AD-conditions and species- and seed-lot-specific traits, of which HS was an important but only one factor. For the use of wildflowers as biogas feedstock, we recommended long retention times and special care with regard to HS species. |
| first_indexed | 2024-04-13T04:29:32Z |
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| id | doaj.art-5cf6d6cabfd44ac4921fc25b057c2048 |
| institution | Directory Open Access Journal |
| issn | 1664-462X |
| language | English |
| last_indexed | 2024-04-13T04:29:32Z |
| publishDate | 2022-07-01 |
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| series | Frontiers in Plant Science |
| spelling | doaj.art-5cf6d6cabfd44ac4921fc25b057c20482022-12-22T03:02:23ZengFrontiers Media S.A.Frontiers in Plant Science1664-462X2022-07-011310.3389/fpls.2022.942346942346Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas ReactorsJuliane Hahn0Paula R. Westerman1Friederike de Mol2Monika Heiermann3Bärbel Gerowitt4Crop Health, Faculty of Agricultural and Environmental Sciences, University of Rostock, Rostock, GermanyCrop Health, Faculty of Agricultural and Environmental Sciences, University of Rostock, Rostock, GermanyCrop Health, Faculty of Agricultural and Environmental Sciences, University of Rostock, Rostock, GermanyDepartment Technology Assessment and Substance Cycles, Leibniz Institute for Agricultural Engineering and Bioeconomy (ATB), Potsdam, GermanyCrop Health, Faculty of Agricultural and Environmental Sciences, University of Rostock, Rostock, GermanyThe use of wildflower species as biogas feedstock carries the risk that their seeds survive anaerobic digestion (AD) and cause weed problems if spread with the digestate. Risk factors for seed survival in AD include low temperature, short exposure and hardseededness (HS). However, it is not possible to predict how AD will affect seed viability of previously unstudied species. In laboratory-scale reactors, we exposed seeds of eight species from a mixture of flowering wild plants intended as biogas feedstock and three reference species to AD at two mesophilic temperatures. Half of the species were HS, the other was non-HS (NHS). Viability was determined using a combination of tetrazolium and germination tests. Viability and germinability were modeled as functions of exposure time using a dose-response approach. Responses to AD varied considerably among species, and none of the considered influencing factors (time, temperature, HS) had a consistent effect. Seed lots of a species differed in inactivation times and seed-killing efficacy. The HS species Melilotus officinalis, Melilotus albus, and Malva sylvestris were particularly AD-resistant. They were the only ones that exhibited biphasic viability curves and tended to survive and germinate more at 42°C than at 35°C. Viability of the remaining species declined in a sigmoidal curve. Most NHS species were inactivated within a few days (Cichorium intybus, Daucus carota, Echium vulgare, and Verbascum thapsus), while HS species survived longer (Malva alcea). AD stimulated germination in the HS species A. theophrasti and its AD-resistance overlapped with that of the most resistant NHS species, C. album and tomato. In all seed lots, germinability was lost faster than viability, implying that mainly dormant seeds survived. After the maximum exposure time of 36 days, seeds of HS species and Chenopodium album were still viable. We concluded that viability responses to mesophilic AD were determined by the interplay of AD-conditions and species- and seed-lot-specific traits, of which HS was an important but only one factor. For the use of wildflowers as biogas feedstock, we recommended long retention times and special care with regard to HS species.https://www.frontiersin.org/articles/10.3389/fpls.2022.942346/fulldose response modelsexposure timeflowering wild plant mixtureshardseedednessphysical dormancyseed survival |
| spellingShingle | Juliane Hahn Paula R. Westerman Friederike de Mol Monika Heiermann Bärbel Gerowitt Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas Reactors Frontiers in Plant Science dose response models exposure time flowering wild plant mixtures hardseededness physical dormancy seed survival |
| title | Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas Reactors |
| title_full | Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas Reactors |
| title_fullStr | Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas Reactors |
| title_full_unstemmed | Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas Reactors |
| title_short | Viability of Wildflower Seeds After Mesophilic Anaerobic Digestion in Lab-Scale Biogas Reactors |
| title_sort | viability of wildflower seeds after mesophilic anaerobic digestion in lab scale biogas reactors |
| topic | dose response models exposure time flowering wild plant mixtures hardseededness physical dormancy seed survival |
| url | https://www.frontiersin.org/articles/10.3389/fpls.2022.942346/full |
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