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Persistent seed banks are equally important in agriculture and invasion biology. While seed vitality persistence exemplifies an eternal uphill battle for weed control in agriculture, it signals a potential invasiveness of species in invasion biology. Considering yield losses caused by Amaranthus retroflexus, Abutilon theophrasti, Chenopodium album and Datura stramonium in agriculture, and the importance of Ambrosia trifida as an emerging invader in Europe, the objective of this study was to test the viability and longevity of the aged seeds of these economically important weeds. Three seed viability/longevity tests were conducted: the crush test, germination test in Petri dishes, and 3,5-triphenyltetrazolium chloride (TTC) test. The results revealed a significant variation in germination potential among the tested species. The highest vitality was observed in 7-year-old seeds of A. retroflexus (41.67 %), followed by 16-year-old A. theophrasti seeds (17.78 %), 13-year-old C. album seeds (15.00 %) and 17-year-old D. stramonium seeds (7.5 %). Furthermore, a remarkable seed longevity was documented in the tested species (with the exception of A. trifida), preserving their germination potential for over half a century. Seed germination was recorded in 49-year-old seeds of D. stramonium, 53-year-old seeds of A. retroflexus, 58-year-old seeds of A. theophrasti and 59-year-old seeds of C. album, in strong evidence of the persistence of these weed species' seeds in the environment.

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Echinochloa crus‐galli (L.) P. Beauv. is one of the most important weeds. It is distributed worldwide and has adapted to diverse habitats and climatic conditions. This study aimed to compare the emergence patterns of two populations of E. crus‐galli from different environments at 11 locations across Europe and the Middle East. Seeds of the two populations were collected from maize in Italy and from spring barley in Norway and were then buried in soil in autumn 2015. In the spring of 2016, the soil was disturbed around the usual seedbed preparation date in each location and emergence was recorded. The soil was again disturbed a year later and emergence was recorded for a second season. Total emergence, the times of onset, end and to 50% emergence and the period between 25% and 75% of emergence were analysed by two‐way ANOVA and principal components analysis. The Italian population showed a higher emergence than the Norwegian population in Southern locations, while the ranking was reversed in Northern locations. In almost all locations, a tendency to emerge earlier was recorded for the Norwegian population, but the periods from 25% to 75% emergence were similar for both populations. Total emergence, and the times of onset and end of emergence seemed to be mainly under genotypic (plus maternal) control, suggesting there were different temperature thresholds for seedling emergence in each population. Conversely, the duration of emergence seemed to be mainly under environmental control. This research confirms the high variability between populations and suggests the need to continue identifying key characteristics for the development of efficient models for seedling emergence in specific climates and/or latitudes. [ABSTRACT FROM AUTHOR]

Common ragweed (Ambrosia artemisiifolia L.) is an annual Asteraceae species native to North America which is highly invasive across Europe and has harmful impacts, especially on human health and agricul-ture. Besides its wide ecological range, particularly its high reproductive power by seeds is promoting its spread to various habitats and regions. To prevent further spread and to control the plant, the European Commission funded projects and COST-Actions involving scientists from all over Europe. A joint trial was set up comprising eight different laboratories from Europe to study seed viability variation in different seed samples. Three different testing methods (viability test with 2,3,5-triphenyltetrazolium chloride (TTC), a germination test combined with a subsequent TTC test and a crush test) were tested within the EU-COST-Action SMARTER network to four different seed origins. The viability test results from different laboratories were compared for variation amongst tests and laboratories. The main aim was to optimise the reliability of testing procedures, but results revealed not only significant effects of seed origin and seed age on seed viability, but also considerable differences between the output of the individual testing methods and furthermore between laboratories. Due to these significant differences in the results of the testing labs, additionally a second test was set up. Twelve Austrian ragweed populations were used for TTC testing to obtain a precise adjustment of the testing method as well as a tight guideline for interpreting the results, particularly for the TTC state "intermediate" since a proper classification of TTC-intermediate coloured seeds is still a challenge when determining viability rates. [ABSTRACT FROM AUTHOR]