Viable Seeds Research Articles

Russian thistle (Salsola tragus) ecology in wheat cropping systems of the Pacific Northwest

Abstract Russian thistle (Salsola tragus L.) is a significant summer annual weed in the semi-arid Pacific Northwest (PNW), causing yield losses of up to 50%. Understanding the biology and ecology of S. tragus is vital for developing effective integrated weed management (IWM) strategies. This study focused on 1) S. tragus emergence and seedbank persistence in two cropping systems: fallow–winter wheat (Triticum aestivum L.) and spring wheat–fallow–winter wheat rotations, and 2) S. tragus plant biomass and viable seed production in fallow and spring wheat fields. A four-year experiment (2020-2023) was conducted at the Columbia Basin Agriculture Research Center (CBARC) in Adams, OR, using a randomized block design with four replications. Salsola tragus seeds were sprinkled only at the beginning of the experiment, and seedling numbers were recorded throughout. Most seedlings emerged in the first year, with the highest rates in spring wheat (72%) and fallow (32%), followed by significantly lower rates (0.25-5%) in subsequent years. Seedling emergence began in late March and early April for the first two years but was delayed to May for the third year. Plant biomass and viable seed production were greater in fallow than in spring wheat, with early-season plants having more biomass than later-emerging plants. Plants emerged between early and mid-May produced the most viable seeds. Viable seed production was very low until it peaked in mid-September. Findings indicated that most S. tragus seedlings emerged in the first year after dispersal coinciding with spring precipitation and lasting approximately two months. Additionally, most S. tragus plants produce viable seeds in September, and seeds persist in the soil for more than two years. These results demonstrate the need for growers to control S. tragus emergence to prevent reinfestations and ultimately the need to control S. tragus plants before September to prevent the species from producing viable seed.

Optimized guidelines for feminized seed production in high-THC Cannabis cultivars

With the partial legalization of high-THC Cannabis sativa across 23 states for recreational use and 38 states for medical purposes in the United States, the Cannabis industry is poised for significant growth. Projected to reach a sales volume of $50.7 billion by 2028, this growth is driven by the trend of lifting Cannabis prohibition. High-THC C. sativa cultivars, containing more than 0.3% delta-9 tetrahydrocannabinol (Δ9-THC) as defined by the 2018 US Farm Bill, are used for both medicinal and recreational purposes. Cannabis sativa is a short day, dioecious, annual plant, where female plants are favored for THC production, which requires seed feminization techniques to ensure an accurate female plant population. This involves using an ethylene inhibitor to induce sex reversal, leading to male flower development on female plants, allowing for self-pollination and the production of feminized seeds. However, challenges such as seed viability and the occurrence of male flowers in progeny have been noted. This review provides guidelines to enhance the production of viable feminized seeds in high-THC Cannabis cultivars. Literature findings indicate that Silver Thiosulfate (STS) is the most effective ethylene inhibitor for sex reversal and seed feminization in high-THC Cannabis cultivars. Specifically, a single dose of 3 mM STS should be applied during the vegetative stage via foliar spraying until runoff, followed by exposure to a short photoperiod of up to 12 hours to induce flowering and seed production. Progeny plants should be assessed for seed germination rate and compared for growth performance with the original parent plant to assess the declining effects of inbreeding. Adhering to these guidelines can improve the quality and viability of feminized seeds, meeting commercial market standards and industry demands for high-THC Cannabis cultivars.

Integrating mechanical and cultural methods for weed control in organic chickpea

Abstract The Northern Great Plains of the United States is a major production region for organic pulse crops that are prone to yield losses due to weeds. Weed management in organic systems relies on the integration of several tactics to stack additive effects and for redundancy to deal with variable efficacy of individual weed management practices. To address the need for effective, integrated weed management, we conducted a 2-yr trial that evaluated the effects of planting date, seeding rate, and preemergent weed control practices (shallow tillage and flame weeding) on weed biomass, crop density, and yield in organically managed chickpea (Cicer arietinum L.) in Montana. Stacking weed management practices increased yields. Early planting had the largest effects on yields, increasing them by 1.8- to 3.6-fold compared with planting 10 to 14 d later. Increasing the seeding rate from the standard rate (43 viable seeds m−2) by 50% increased yields by 47% from 889 to 1,304 kg ha−1. Both preemergent weed control practices increased yields by 40% to 50 % relative to the non-weeded controls. By integrating all three practices, yields of organic chickpea increased greater than 6-fold from 318 kg ha−1 in the controls to 2,006 kg ha−1. The effects of weed control treatments on midseason weed biomass were complex and variable. Although efficacy of the cultural (seeding rate and planting date) and physical (preemergent) treatments on weed biomass varied between years and when combined with other treatments, their full integration, that is, early planted, at higher seeding rate, and preemergent weed control, produced consistently lower weed biomass (84% reduction on average) compared with the standard grower practice (later planting, standard seeding rate, no preemergent weed control). The results lend support to the concept of integrating multiple weed management practices to achieve weed control and high yields in organically managed crops.

Seasonal Variations in Seed Viability and Vigor of Hancornia speciosa Under Osmoprotective Storage Conditions

Seasonal Variations in Seed Viability and Vigor of Hancornia speciosa Under Osmoprotective Storage Conditions

Biochemical Changes and Germination Response of Indian Sandalwood (Santalum album L.) Seeds Subjected to Biopriming Techniques and Variable Post-priming Storage

Understanding of the storage behaviour of endangered plant species such as Indian Sandalwood, Santalum album L. is important for successful conservation. We tested biopriming method with five biopriming agents (e.g. Effective microorganisms; Plant growth promoting rhizobacteria (PGPR-I and PGPR-II); Pseudomonas fluorescens and Piriformospora indica) with four uniform durations of treatments viz. 2, 4, 6 and 8 days. Hydropriming was also performed with similar condition for comparison of seed performance. The study examined the biochemical changes that occur in Sandalwood seeds during different post-priming storage periods (0, 30, 60, 90 days) to assess the efficacy of biopriming techniques on seed germination and health. Biopriming with Pseudomonas fluorescens for eight days recorded the highest germination percentage (70.67%) and the highest germination rate index (0.84). Longer durations of PGPR-I and Piriformospora indica treatment (6-8 days) lowered the imbibition period and mean germination time while increasing the germination rate. After a post-priming storage period of 30 days, only EM and Pseudomonas fluorescens treated seeds germinated while all other treatments failed to germinate. Absence of germination in any biopriming group at 60 and 90 days storage period indicated that the sandal seeds deteriorated over extended storage period. The reduction in seed viability of sandal seeds was consequent to the changes in the biochemical characteristics and action of enzymes (α and β amylases) involved in seed food reserve depletion and loss in membrane integrity.

The development of an in vitro floral culture transformation system for quinoa

AbstractBecause of its high-quality seed protein and ability to thrive in marginal habitats, Chenopodium quinoa has been identified as an important emerging grain crop for global food security. However, the lack of an efficient and robust transformation system has been a barrier for conducting the advanced genetic studies needed to better understand and improve the species for agronomic traits. Here we present a novel transformation system based on Agrobacterium-mediated transformation of in vitro floral culture. Quinoa floral cultures were established from inflorescences that naturally formed on plants grown in vitro. When placed on a cytokinin-containing medium, chopped inflorescences rapidly generated highly meristematic floral cultures, primarily composed of floral buds, flowers at various developmental stages, inflorescence shoots, and leafy structures. Transformation of these cultures with Agrobacterium carrying selectable and visual markers (NPTII and GUS) produced independent, stably transformed meristematic cultures resistant to paromomycin after an extended selection period (about 3 mo with sub-culture occurring every 15 d). Transformation frequency was about 20% and was calculated as the number of independent transformed events per initial number of floral culture explants used for transformation. In vitro flowers and inflorescences from putative transgenic events self-pollinated naturally and produced viable seeds that germinated without dormancy. We also demonstrated that flowering shoots could be successfully grafted onto wild rootstock to increase the number of seeds generated from T0 floral shoots. Molecular and phenotypic analysis of the progeny confirmed that the transgenes were stably integrated and inherited according to expected Mendelian ratios.

Evaluation of spring barley cultivars released in Belarus under the environmental conditions of the Northern Trans-Urals

Background. Studying the genetic diversity of ex situ barley accessions under contrasting environmental conditions (humid with a lack of heat, favorable, arid, etc.) makes it possible to assess them according to the duration of the growing season, resistance to lodging, potential productivity, drought resistance, grain quality, and environmental plasticity. Materials and methods. The results of an 8-year trial (2016–2023) of 11 spring barley accessions of Belarusian origin in the northern forest-steppe zone of Tyumen Province are presented. The experiments followed the protocols adopted for the state variety trials. An SKS-6-10 seeder was used for sowing, the plot area was 5 m2 , and cv. ʻAbalakʼ served as the reference. The seeding rate was 550 viable seeds per 1 m2 . Results. A majority of the studied accessions matured later than the medium-ripening reference cultivar. Weather conditions during the growing season in the Northern Trans-Urals had a decisive effect on the harvest formation, protein content and starch content in barley grain (74.6%, 70.8% and 81.8%, respectively). The effect of the genotype on these indicators was 7.9%, 17.5% and 6.2%, respectively. Starch content also depended on the genotype × environment interaction (9.7%). Fat content was almost equally affected by the genotype (25.1%) and the environment (26.7%). The genotype × environment interaction was more significant (31.2%). Conclusion. The following sources were identified among the tested cultivars: ‘Vodar’ (high yield, drought tolerance, etc.); ‘Magutny’ (high yield, and environmental plasticity); ‘Khago’ (large grain, low hull content, and increased protein and starch content levels); ‘Lipen’ (high test weight, increased starch content, and environmental plasticity); ‘Fobos’ (drought tolerance, and increased protein content); ‘Dublet’ (lodging resistance, and increased protein content); ‘Taler’ (reduced protein content, and environmental plasticity); ‘Pospekh’ (reduced protein content).

Weighing the risks and benefits of flowering early in the spring for the woody perennial Prunus pumila.

There are advantages to flowering early in the spring, including greater pollinator fidelity and longer fruit maturation time. But plant phenology has advanced in recent years, making many plants vulnerable to freezing damage from late frosts. To determine the costs and benefits of flowering early in the growing season, we exposed Prunus pumila plants to two freezing treatments and a delayed flowering treatment in subsequent years. Data were collected on ovary swelling, fruit production, and pollinator visitation on hand- and open-pollinated plants in all treatments. We also measured tissue damage after freeze events. Our results suggest that flowering time and temperature affect reproductive success, with fewer fruits produced after hard freezes. The same was not true for light freezes, which had minimal impact on reproduction. Freezing damage to plants after a hard freeze did affect the number of dipteran pollinators but not the overall pollinator visitation rate. Despite the clear impact of freezing temperatures on plant reproduction, flowering early provided an advantage in that reproductive output decreased with delayed flowering. Our findings suggest that Prunus pumila will retain the ability to attract pollinators and produce viable seeds if exposed to false spring conditions that involve a light freeze, but hard freezes may reduce yield by an order of magnitude. Although the advantages to flowering early may outweigh the risk of freezing damage under current conditions, it is possible that flower viability may be constrained under continued climate warming.

Germination success of seeds ingested by Saguinus bicolor

ABSTRACT Frugivory and seed dispersal are fundamental ecological interactions influencing plant population dynamics and distribution. Still, understanding how the ingestion of seeds by fruit-eating animals affects seedling emergence performance remains poorly documented. Seed dispersal through animal ingestion can either promote or hinder germination. In this study, we assessed how seed ingestion by Saguinus bicolor, a critically endangered primate from the Brazilian Amazon, affects germination rate and germinability. As primate seed ingestion often improves seed germination, we predicted that germination rate and germinability would be higher in seeds defecated by the tamarins if compared to hand-extracted seeds. Of the 23 species, five did not germinated in either the control or gut-passage treatments. Among the ones that germinated, nine had an average increase in germinability, two decreased in germinability, and seven had a neutral effect. The germination rate increased in four species, reduced in eight species and had a neutral effect in six of the species. Most of the seeds that passed through the tamarins' digestive tract successfully germinated, demonstrating that seed ingestion by pied tamarins can benefit the plant populations by dispersing viable seeds through the landscape.

Evaluating the role of insect pollinators in the viability of true seeds of shallot in tropical agroecosystems

Pollen transfer in tropical agroecosystems to increase seed production has received limited research, notably on shallot pollination and insect pollinators. This study evaluated how insect pollinators optimize shallot seed production in tropical agroecosystems, i.e. Batu and Malang Districts in Indonesia. This study was conducted from June to October in 2023. We examined pollinator diversity, foraging behavior, and the effectiveness of dominating insect pollinators during umbel flower anthesis, as well as visiting insect foraging and visiting patterns. We assessed pollinator effectiveness by comparing visitation rates under four treatments. A total of 21 insect species belonging to three orders visited the shallot flowers, of which 14 species have the potential to act as pollinators. Apis cerana Fabricius, 1793 (Hymenoptera: Apidae) and Lucilia sericata (Meigen, 1826) (Diptera: Calliphoridae) emerged as potentially effective pollinators. Air temperature significantly influenced pollinator activity in visiting anthesis umbels. Evaluations of pollinator efficiency showed that A. cerana was more efficient than L. sericata in promoting the production of true shallot seed and has a significant role in ensuring high-quality pollination. This highlights the necessity of comprehending the specialized contributions of pollinators for shallot seed production.

Agrobacterium-mediated Cuscuta campestris transformation as a tool for understanding plant-plant interactions.

Cuscuta campestris, a stem parasitic plant, has served as a valuable model plant for the exploration of plant-plant interactions and molecular trafficking. However, a major barrier to C. campestris research is that a method to generate stable transgenic plants has not yet been developed. Here, we describe the development of a Cuscuta transformation protocol using various reporter genes (GFP, GUS, or RUBY) and morphogenic genes (CcWUS2 and CcGRF/GIF), leading to a robust protocol for Agrobacterium-mediated C. campestris transformation. The stably transformed and regenerated RUBY C. campestris plants produced haustoria, the signature organ of parasitic plants, and these were functional in forming host attachments. The locations of T-DNA integration in the parasite genome were confirmed through TAIL-PCR. Transformed C. campestris also produced flowers and viable transgenic seeds exhibiting betalain pigment, providing proof of germline transmission of the RUBY transgene. Furthermore, RUBY is not only a useful selectable marker for the Agrobacterium-mediated transformation, but may also provide insight into the movement of molecules from C. campestris to the host during parasitism. Thus, the protocol for transformation of C. campestris reported here overcomes a major obstacle to Cuscuta research and opens new possibilities for studying parasitic plants and their interactions with hosts.

A global database of soil seed bank richness, density, and abundance.

A soil seed bank is the collective name for viable seeds that are stored naturally in the soil. At the species or population level, the ability to form a seed bank represents a strategy for (re)colonization following a disturbance or other change in the local environmental conditions. At the community level, seed banks are thought to buffer local diversity during periods of environmental change and are often studied in relation to the potential for passive habitat restoration. The role that seed banks play in plant population and community dynamics, as well as their importance in the agricultural sector, means that they have been widely studied in ecological research. This database is the result of a comprehensive literature search, including all seed bank studies from the Web of Science from which data could be extracted, as well as an additional search of the Russian language literature. The database contains information on the species richness, seed density, and/or seed abundance in 3096 records from at least 1929 locations across the world's seven continents, extracted from 1442 studies published between 1940 and 2020. Records are grouped into five broad habitat categories (aquatic, arable, forest, grassland-including shrubland-and wetland), including information relating to habitat degradation from, or restoration to other habitats (total 14 combinations). Sampling protocols were also extracted for each record, and the database was extensively checked for errors. The location of each record was then used to extract summary climate data and biome classification from external published databases. The database has several potential uses. The large geographical spread relative to many other global biodiversity datasets is relevant for investigating patterns of diversity in biogeographical or macroecological contexts. Habitat type and status (intact, degraded, and restored) can be used to provide insights for biodiversity conservation, while the potential effects of sampling method and effort can be used to inform optimized data collection for future seed bank studies. This database is released under the CC-BY license.

Nitrogen fertilization management and seeding density differently affect net blotch incidence and grain yield in one two-row and one six-row cultivar of barley

A two-year field experiment was carried out on barley (Hordeum vulgare L.) to test the effect of cultivar, N fertilization management and seeding density on crop growth, net blotch (NB) disease occurrence and yield. The three variables were factorially combined in a split-split-plot design as follows: 1) two barley cultivars, one two-row (H. v. distichum, cv Callas) and one six-row (H. v. hexastichum, cv Azzurro); 2) four N application schedules differing for rates and/or timing of N supply: unfertilized control; fertilized with 35kgha-1 of N at BBCH29 plus 30kgha-1 of N at BBCH31; fertilized with 70kgha-1 of N at BBCH29 plus 60kgha-1 of N at BBCH31; fertilized with 130kgha-1 of N simultaneously at BBCH31; 3) four seeding densities: 100, 200, 400 and 800 viable seeds m2.The three variables affected crop growth and NB occurrence resulting in different grain yield and quality. Results varied with the seasonal trend, in particular with rainfall regime and air temperature, for their possible effect on soil N dynamics and the presence of NB, which resulted in different source capacity, and for their effect on grain setting and filling, i.e., the sink capacity. Both N fertilization and seeding density increased NB pressure, with seeding density affecting the disease even under unfavourable weather conditions for NB development. At the maximum N fertilization rate, delaying N application helped limit plant height and the related risk of lodging, as well as NB symptoms, resulting in greater hectolitre weight and protein content together with no appreciable decrease of grain yield, provided seeding density was close to optimal (i.e., 400 seeds m-2) or higher.

Seed quality and relative lignan profiles of sesame prospected from northern Ghana

The sesame seed contains oil, protein, dietary fibre, and several minerals and it is also a store of lignans. Lignans are key selection factors for sesame quality due to their health, nutritive and market value. In Ghana sesame growers rely on wild or undocumented planting seeds which are of mixed colouration and its lignan content is ambiguous. The objective of this study was to segregate street sesame seeds into component colour fractions and subsequently evaluate the consistency of lignans in the seed fractions. Sesame seeds were collected from street vendors in northern Ghana and were segregated into seed fractions based on the pericarp colour. The viability of seed fractions stored at different temperatures (ambient, 5 °C, 0 °C) over time and lignan contents of single or bulk mixed seeds were verified. The collected seeds were of mixed colouration with approximately 4 % debris, 40 % white, 36 % cream, and 20 % dark coloured seeds by weight. The viability of the seeds was 67–85 % depending on pericarp colour. White seed fractions which had the highest proportion by weight had a significantly (p = 0.0275) higher viability (85 %) than the dark seeds which had the least viability (67 %). The seeds lost viability over time. However, seeds stored at 0 °C maintained a viability of 77 % at the fourth year. There were differences in the relative abundance of lignans for both bulk seeds and, single seeds with different pericarp colours. The most abundant occurring lignans in the seeds were sesamin, sesamolin and sesaminol and its downstream glucosides. The source of seed or pericarp colour was not predictive of seed viability or lignan composition. These findings provide baseline data on seed quality including an improved storability under cold environments. It also gives an insight into how mixed seeds of variable pericarp colours can have distinct characteristics. Although the mixed coloured seeds had no implications for varied quality including lignan content, the international market for sesame requires that seeds are of consistent colour.

Passive revegetation limited by seed availability in a salt marsh sediment addition site

Many approaches to restoring salt marsh habitats assume flora will naturally colonize the restoration site following the reinstatement of tidal hydrology that is appropriate for halophytes. However, this passive strategy can fail to meet restoration targets because of unfavorable site conditions and/or limited propagule dispersal. This study analyzes propagule availability in a restored southern California salt marsh that experienced slow passive revegetation following sediment addition to combat subsidence‐driven habitat loss. We performed a seedling emergence experiment to assess the quantity and species composition of viable halophyte seeds in the restoration site compared to nearby established salt marsh habitat. Additionally, we irrigated seed bank samples with freshwater or saltwater to test the effects of restoration site salinity conditions on seedling emergence and survival. Due to the proximity of the restoration site to seed sources, we expected to find ample seeds within its seed bank. However, only two seedlings emerged from restoration site seed bank samples (collected over 1.18 m2 of soil surface area), compared to an average of 44.33 seedlings from control site samples. Control site samples receiving saltwater irrigation had similar quantities of seedlings emerge, but seedlings in salt water had a reduced survival rate compared to seedlings in the freshwater treatment. Overall, these results suggest that passive restoration should be paired with techniques that retain seeds, such as increasing the topographic complexity of the restoration site. However, in scenarios where salinity or elevation may limit seedling recruitment, active planting should be considered to speed restoration trajectories.

Study of germination of collection samples of wild flora of Astana botanical garden

The present study is devoted to the main tasks of seed bank laboratories, among which the formation, study and conservation of seed collections of both natural and introduced flora of Central and Northern Kazakhstan are emphasized. This work emphasizes the importance of maintaining optimal conditions for seed collection in these regions, which is a key aspect for successful seed management, conservation and restoration of plant communities. Expedition trips, conducted annually between July and September, are synchronized with the growing seasons of the plants and take into account weather conditions that directly affect the efficiency of seed collection.During such visits, 56 forms of wild flora were collected, mainly on the territory of the Kokchetavskaya Upland, Central-Kazakhstan shallow meadow and Akmola region, including Shortanda district, as well as in the unique ecosystems of SNPP “Burabai” and the vicinity of Makinki village. The collected genetic material plays a key role in biodiversity conservation and can be used for further scientific research as well as for practical needs related to ecosystem restoration.As part of this work, a laboratory study was also conducted to investigate the viability of the selected seeds. The results of the study will help to further understand the characteristics and factors that determine the viability of seeds of different forms, which is crucial for their subsequent use in botanical collections. This study emphasizes the relevance of the selected topic, as well as the importance of conservation and management of seed resources in conditions of ecological vulnerability, which is of significant importance for sustainable environmental protection and conservation of plant diversity in Central and Northern Kazakhstan.

Morphological and Germination Characteristics of Alhagi maurorum Boiss. and Salsola richteri Kar. Seeds Distributed in the Karakum Desert of Turkmenistan

The Karakum Desert is the largest desert in Turkmenistan and covers a significant part of Central Asia. This desert is home to plant species that can adapt to hot, dry, and barren conditions. During the summer months, the Karakum Desert can get extremely hot, with temperatures reaching up to 50 °C, while in winter, it can drop to -20 °C. Therefore, the desert conditions significant seasonal temperature differences. In winter, rainfall is very low, snow rarely falls, and quickly melts. Afghan winds have an impact on the desert vegetation. The desert vegetation mainly consists of short grasses and woody shrubs. Despite the scarcity of rainfall and high temperatures during the summer months, steppe plants have generally been able to adapt to the harsh conditions of the desert. There are also species that have adapted to the desert climate, such as Alhagi maurorum Boiss., Haloxylon persicum Bunge, Haloxylon aphyllum (Minkw.) Iljin), Solanum nigrum L., and Salsola richteri Kar. These plants are highly valuable in terms of nutrition for animals and are used as winter animal feed in rural areas. In this study, the seed and germination characteristics of Alhagi maurorum Boiss. and Salsola richteri Kar, which are tree and shrub-like plants that can adapt to Karakum Desert conditions, were examined. In laboratory study, the morphological characteristics of the seeds were determined, and vitality and germination tests were conducted. Information was obtained about the germination adaptation of these plants in desert ecosystems. As a result of the study, it was determined that S. richteri had a very low rate of viable seeds and no germination, while the germination process of Alhagi maurorum could take a considerably long time.

Non-Destructive Seed Viability Assessment via Multispectral Imaging and Stacking Ensemble Learning

Non-Destructive Seed Viability Assessment via Multispectral Imaging and Stacking Ensemble Learning

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

IntroductionPlant 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.MethodsSeed 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 lab-scale AD for 1 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.Results and discussionSeed 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.

Lights and shadows in the application of the resazurin test on Macaronesian flora

Seed viability tests are essential for seed bank management and the ex situ conservation of genetic biodiversity. Although there are different methods for determining the viability of the seeds, none of them is 100% effective, many require a considerable number of resources, some are not entirely reliable, others are time-consuming, they destroy the seeds, and/or can even be dangerous for the researcher/laboratory technician. However, a new simple, quick and non-destructive seed viability test has been recently described. This method is based on the reduction of resazurin to highly fluorescent resorufin by the respiration of a yeast activated by solute leak from non-viable seeds. In the present study, we tested this method in 53 taxa from 28 families from the Macaronesian region. We did not find a significant correlation between the germination and the resazurin test. Although there were several taxa that showed a high positive correlation, many other taxa exhibited a low positive correlation. Besides, we did not detect standard absorbance values from the resazurin test that determined seed health conditions. Though the resazurin viability method could be a good viability test, this should be standardized for each taxon.