Toward an Investigation of Diversity and Cultivation of Rye (Secale cereale ssp. cereale L.) in Germany: Methodological Insights and First Results from Early Modern Plant Material

Rye (Secale cereale ssp. cereale L.) is a secondary domesticate, considered to have originated as a weed in wheat fields and to have developed traits of domestication by evolving similar physiological and morphological characteristics to those of wheat. Although it migrated into Europe as a weed possessing domestication traits, it became one of the most significant crops grown in large parts of Europe from the medieval period onward. Within the modern borders of Germany, rye was grown using at least two divergent cultivation practices: eternal rye monoculture and three-field rotation. The straw of rye was used to produce Wellerhölzer, which are construction components in traditional half-timbered houses that have enabled a desiccated preservation of the plant remains. In order to assess the impact of cultivation practices, local environmental conditions and genetic variation on the genetic diversification of rye, we seek to integrate well-established archaeobotanical methods with aDNA sequencing of desiccated plant remains obtained from Wellerhölzer from Germany. In the current contribution, we present a proof of concept, based on the analysis of plant remains from a Wellerholz from the Old Town Hall of Göttingen. We use arable weed ecology to reconstruct cultivation practices and local environmental conditions and present a phylogenetic analysis based on targeted loci of the chloroplast and nuclear genome. Our results emphasise that the study of desiccated remains of plants from Wellerhölzer offer a unique opportunity for an integration of archaeobotanical reconstructions of cultivation practices and local environment and the sequencing of aDNA.

A high diversity of mechanisms endows ALS-inhibiting herbicide resistance in the invasive common ragweed (Ambrosia artemisiifolia L.)

Ambrosia artemisiifolia L. (common ragweed) is a globally invasive, allergenic, troublesome arable weed. ALS-inhibiting herbicides are broadly used in Europe to control ragweed in agricultural fields. Recently, ineffective treatments were reported in France. Target site resistance (TSR), the only resistance mechanism described so far for ragweed, was sought using high-throughput genotyping-by-sequencing in 213 field populations randomly sampled based on ragweed presence. Additionally, non-target site resistance (NTSR) was sought and its prevalence compared with that of TSR in 43 additional field populations where ALS inhibitor failure was reported, using herbicide sensitivity bioassay coupled with ALS gene Sanger sequencing. Resistance was identified in 46 populations and multiple, independent resistance evolution demonstrated across France. We revealed an unsuspected diversity of ALS alleles underlying resistance (9 amino-acid substitutions involved in TSR detected across 24 populations). Remarkably, NTSR was ragweed major type of resistance to ALS inhibitors. NTSR was present in 70.5% of the resistant plants and 74.1% of the fields harbouring resistance. A variety of NTSR mechanisms endowing different resistance patterns evolved across populations. Our study provides novel data on ragweed resistance to herbicides, and emphasises that local resistance management is as important as mitigating gene flow from populations where resistance has arisen.

Genetic Variability of Acetolactate Synthase (ALS) Sequence in Centaurea Cyanus Plants Resistant and Susceptible to Tribenuron-methyl

Centaurea cyanus, belonging to the Asteraceae family, is an arable weed species being encountered mainly in the fields with cereals, sugar beet, and corn. C. cyanus high genetic variability has recently been reported, however, little is known about sequence variability in the context of herbicide resistance. C. cyanus resistance was found mainly against acetolactate inhibitors (ALS) inhibitors, but no ALS sequence information concerning herbicide resistance mechanism has been published yet. Therefore, the aim of this study was to determine ALS sequences for biotypes susceptible and resistant to tribenuron-methyl in order to identify possible mutations conferring the resistance. DNA isolation from susceptible and resistant plants was followed by PCR amplification and sequencing of ALS sequence. As a result different lengths of DNA products were obtained. Moreover, both nucleotide and amino acid sequence analysis revealed high sequence variability within one plant as well as between plants from the same biotype. In a few resistant plants, six changes in amino acid sequence were identified in comparison to susceptible ones. However, these preliminary studies require further investigation toward confirming the significance of these mutations in herbicide resistance development. This study provides the first attempt in the research on C. cyanus target-site resistance mechanism.

Arable weeds of the Scottish Borders

Many years of fieldwork have led the authors to hypothesise that there is a single relatively species-rich arable weed community present across the Scottish Borders that is best expressed in broad-leaved root crops and in set-aside on imperfectly-drained soils, while the species-poor communities typically found in cereal crops are a degraded form of this. 102 samples have been studied to test this hypothesis and to search for a community typical of slightly calcareous well-drained soils. The community typical of imperfectly-drained soils has been defined and is considered to be a species-rich variant of the NVC OV13 Stellaria media-Capsella bursa-pectoris open habitat community. Species typical of well-drained soils have been shown to be scarce and not to form a distinct community, though they may well have done so in the past.

Weed vegetation in conventional and organic farming in West Bohemia (Czech Republic)

The paper presents species richness and composition of arable weed vegetation in the region of West Bohemia (Czech Republic) in different types of farming (conventional and organic) and grown crops (winter and spring cereals, wide-row crops). During the field survey in the years 2007 to 2017, 105 phytocoenological relevés were recorded. The average species richness in one relevé was significantly higher in organic farming, as well as total weed cover. The lowest species richness was found in wide-row crops. Recently widespread species belonged to the most frequent species in our study. Based on multivariate statistics, the effects of variables on the occurrence of weed species were found as statistically significant. Most of the variability in data was explained by crop, following by type of farming. Weed species of Fabaceae Lindl. family (especially Vicia L.) and many perennial species positively correlated with the organic type of farming. Endangered species were found mainly in organic farming and cereals. Less intensive cultivation with a higher weed cover is beneficial for the promotion of biodiversity.

Occurrence of native weed species on arable land – Effect of different environmental factors

Native species form a substantial part of arable weed communities. The objective of this survey was to study the occurrence of native species in arable fields in the Czech Republic related to applied management systems (conventional and organic farming), crops (winter cereals, spring cereals, wide-row crops) and environmental conditions at different altitudes. In 2006–2018, a phytocoenological survey (320 relevés) was performed across the Czech Republic. In total, 180 weed species were recorded, of which 43.33% were considered as native (78 species). The net effects of all the studied variables on the occurrence of native species were found as statistically significant. Most of the variability was explained by the altitude, followed by the crop and type of farming. The highest occurrence of native weeds was noticed in organic farming and cereals and increased with an increasing altitude. The higher incidence in higher elevations can be connected to the more intensive agriculture in the lowlands.

Growth and Phenology of Vulpia Myuros in Comparison with Apera Spica-Venti, Alopecurus Myosuroides and Lolium Multiflorum in Monoculture and in Winter Wheat

Vulpia myuros has become an increasing weed problem in winter cereals in Northern Europe. However, the information about V. myuros and its behavior as an arable weed is limited. Field and greenhouse experiments were conducted in 2017/18 and 2018/19, at the Department of Agroecology in Flakkebjerg, Denmark to investigate the emergence, phenological development and growth characteristics of V. myuros in monoculture and in mixture with winter wheat, in comparison to Apera spica-venti, Alopecurus myosuroides and Lolium multiflorum. V. myuros emerged earlier than A. myosuroides and A. spica-venti but later than L. multiflorum. Significant differences in phenological development were recorded among the species. Overall phenology of V. myuros was more similar to that of L. multiflorum than to A. myosuroides and A. spica-venti. V. myuros started seed shedding earlier than A. spica-venti and L. multiflorum but later than A. myosuroides. V. myuros was more sensitive to winter wheat competition in terms of biomass production and fecundity than the other species. Using a target-neighborhood design, responses of V. myuros and A. spica-venti to the increasing density of winter wheat were quantified. At early growth stages “BBCH 26–29”, V. myuros was suppressed less than A. spica-venti by winter wheat, while opposite responses were seen at later growth stages “BBCH 39–47” and “BBCH 81–90”. No significant differences in fecundity characteristics were observed between the two species in response to increasing winter wheat density. The information on the behavior of V. myuros gathered by the current study can support the development of effective integrated weed management strategies for V. myuros.