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Bromus sterilis L. (barren brome) is one of the most economically important noxious grass weeds in the winter cereal fields of Europe. Its ecological behaviour in this agro-climatic region should be assessed for effective weed control strategies. The present study was conducted to assess the dormancy and germination response of the B. sterilis population from the Czech Republic under thermal, light, and stress conditions. The dormancy loss experiment revealed that seeds exposed to the light regime showed a remarkably lower percentage of germination, and under alternating temperatures of 10/20 °C in dark conditions, rapid loss of primary dormancy was observed. This population was found to germinate across a wide temperature range of 5-35 °C, with the highest germination rate at 25 °C (T50 = 1.14 days in dark, 1.21 days in light) and the germination time increased with decreasing temperatures below 25 °C. Further, due to fitness advantage, herbicide-resistant (R) biotypes were found to be more stress-tolerant than susceptible (S) biotypes under salinity and drought conditions. In the highest stress conditions, the germination of S biotypes was negligible, while R biotypes can germinate under high stress, but germination decreased below 25 °C. The current findings may add value to effective weed control strategies using prediction models based on seed dormancy and germination values under different hydrothermal conditions.

Grassland as a part of farmland is important for agrobiodiversity, soil protection and agricultural production (grazing, hay production). In the Czech Republic, grassland area increases with increasing altitude. In this study we evaluated the period 1966-2021 and the change in grassland area in different locations in South Bohemia region: fertile lowlands (Písek, České Budějovice, Tábor districts) and marginal uplands (Český Krumlov, Prachatice districts). Data on land use including the share of grassland were obtained from the Czech Cadastral and Surveying Office and Czech Statistical Office. In the upland districts, there is the largest share of grassland areas in the whole region. The prevalence of grasslands is probably due to the geographic and climatic conditions, which are challenging here. Our research shows the results of changes in grassland areas between 1967 and 2021, with regard to the assessed districts. The difference in the percent area of grassland in 2021 compared to 1967 is -0.04 to -1.77 for lowlands, and +1.45 to +5.99 for uplands. Despite this, uplands farmers practice relatively extensive farming methods and extensive grazing due to low ruminant numbers. Although farmers maintain relevant carbon sinks, it is unlikely to increase the carbon stocks per hectare of extensive grasslands on an annual basis, which would be a barrier to participation in a carbon farming system.

Our objectives were to characterise arable weeds of the Czech and Slovak Republic in cereals, especially considering important groups of species: thermophilic, weedy grasses, and rare and endangered species. The three-year phytocoenological survey was conducted from 2006 to 2008 in five climatic regions and eight different soil types. 379 relevés were recorded, and 281 weed species were found. The effects of both the climatic region and soil type were found to be statistically significant. Species richness increased with altitude. Several species were distinctly associated with soil type, from fertile chernozems to less fertile cambisols, while fluvisols were strongly associated with e.g. Calystegia sepium (L.) R. Br. The incidence of species outside their expected regions generally fit two categories: the most pervasive weeds found almost in all climate regions, such as Echinochloa crus-galli (L.) P. Beauv., or rare weeds in higher altitudes than expected, such as Lolium temulentum L. Rare and endangered species were more likely to be found in a colder climate and poorer soils, and this is linked to less intensive management; however, not all endangered arable species can tolerate such conditions. Even though this data is not recently collected, this is still valuable information on the distribution of weedy species, especially concerning the current interest in maintaining biodiversity.

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.

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.

Six sunflower herbicides were tested at two application rates (1N and 2N) on three locations (with different soil types) within three years (2015-2017). Efficacy of the tested herbicides on Chenopodium album increased with an increasing cation exchange capacity (CEC) of the soil. Efficacy of pendimethalin was 95%, flurochloridone and aclonifen 94%, dimethenamid-P 72%, pethoxamid 49% and S-metolachlor 47%. All tested herbicides injured sunflower on sandy soil (Regosol) which had the lowest CEC, especially in wet conditions (phytotoxicity 27% after 1N application rate). The highest phytotoxicity was recorded after the application of dimethenamid-P (19% at 1N and 45% at 2N application rate). Main symptoms of phytotoxicity were leaf deformations and necroses and the damage of growing tips, which led to destruction of some plants. Aclonifen, pethoxamid and S-metolachlor at 1N did not injure sunflower on the soil with the highest CEC (Chernozem) in any of the experimental years. Persistence of tested herbicides was significantly longer in Fluvisol (medium CEC) compared to Regosol and Chernozem. Dimethenamid-P showed the shortest persistence in Regosol and Chernozem. The majority of herbicides was detected in the soil layer 0-5 cm in all tested soils. Vertical transport of herbicides in soil was affected by the herbicide used, soil type and weather conditions. The highest vertical transport was recorded for dimethenamid-P and pethoxamid (4, resp. 6% of applied rate) in Regosol in the growing season with high precipitation.

The aim of the study was to estimate changes in the floristic composition near Švýcárna lodge (1304 m a.s.l.), where cattle grazing after a long-term management cessation was introduced on a pasture area of 3.6 ha in 2012. The pasture was divided into two grazing sub-localities: P1 (Nar) with dominance of Nardus stricta and Avenella flexuosa and P2 (Des) with dominance of Deschampsia cespitosa. For grazing, Highland Cattle was used with a stocking rate up to 1 livestock unit per ha and year. The floristic composition was evaluated and statistically analyzed. After six years of restored grazing the overall species richness enhanced and a higher dominance of rare and endangered species was found. The dominance of some common species like Vaccinium myrtillus, and Calamagrostis villosa tended to decrease within a grazing period in favor of new species colonisation.

Understanding the impact of farming practices on the composition of weed communities has important implications for the sustainability of weed management strategies. This study analyses data from a 40-year experiment established at two sites in the Czech Republic in 1972. The impact of herbicide strategies on the weed communities was evaluated in multi-crop rotation (MCR) with 50% cereals, and simple crop rotations (SCR) with 75% cereals. The following two herbicide strategies were compared: (1) simple treatment with synthetic auxins only in the simple crop rotation, and (2) targeted herbicide combinations with particular use of sulfonylureas, triazines, ureas and synthetic auxins. Untreated plots were included for reference purposes. Results showed that crop was the major factor determining weed community composition and explained 18% of the total variation in the case of untreated controls. However, herbicide treatment reduced the crop effect to 11%. The highest average increase of Shannon’s diversity index was by 25.4% after 44 years at the untreated plots in SCR, and it decreased by 15.1% at the treated plots in MCR. Weed species evenness € increased at all plots by an average of 23%. Simpson’s dominance index decreased at untreated plots in both crop rotations and plots treated with auxins, with the highest 44.8% decrease at the untreated plots in SCR. On the contrary, Simpson’s index increased by 33,3% on the treated plots in MCR. Herbicide selection depended on the occurrence and density of target weed species, and led to greater decrease in weed diversity and population densities in the diversified crop rotations.

Metazachlor and pendimethalin are the most used herbicides in kohlrabi. The main objectives of the present study were to evaluate the residual activity of herbicides pendimethalin and metazachlor in kohlrabi and soil under different irrigation regimes and to evaluate the effect of soil adjuvants on the residual activity of tested herbicides. Pendimethalin dissipation half-life (17.3-38.3 days) was higher than metazachlor dissipation half-life (12.1-16.8 days). The pendimethalin half-life was not affected by an adjuvant, irrigation, and an experimental year. Pendimethalin mobility in the soil was affected more by natural precipitation than by irrigation. The use of adjuvant did not affect pendimethalin leaching in dry weather conditions. In wetter natural conditions, a higher pendimetha-lin leaching was found at early-irrigated plots treated by an adjuvant (9.39% of the applied dose was detected in the soil layer 5-10 cm). Metazachlor dissipation half-life was not affected both by an adjuvant and by irrigation. In the soil layer 5-10 cm, metazachlor was detected only in 2016 on intensively irrigated plots without the use of adjuvant (0.072 µg/g). A concentration of pendimethalin in kohlrabi tubers ranged between 2 and 7 µg/kg. The highest concentration of pendimethalin was detected in tubers, which were intensively irrigated shortly after the application of herbicides without an adjuvant, especially when natural precipitation was high. Metazachlor was not detected in any of the tested kohlrabi samples.

The aim of this work was to verify and assess the tolerance of the PR63E82 (ExpressSun) sunflower cultivar to tribenuron, propaquizafop and their tank-mix combination in two rates under various weather conditions. Three small-plot field trials were carried out on sunflower in Prague, Czech Republic, from 2015 to 2017. High phytotoxicity (25-56%) of tribenuron (TBM) + non-ionic surfactant was observed in 2015 and 2016 when the sunflower was sown in mid-April. In 2017, phytotoxicity was significantly lower (4-6%), probably due to a later sowing of sunflower (May), and hence higher temperatures. The main symptoms of TBM phytotoxicity were leaf chlorosis, necrosis and growth retardation. Propaquizafop (PQF) injury was minimal in 2015 and 2017. A higher phytotoxicity (10-13%) was recorded in 2016, probably due to a hail which occurred 2 days after T2 (second application term (sunflower BBCH 14)) application. Plant injury had puckered leaves and also made more side branches. TBM + PQF damaged sunflower plants most of the tested herbicide treatments (phytotoxicity 3-62%). High phytotoxicity caused stem branching, increased number of sunflower heads and decreased yield.

The impact of herbicide application on weed community changes was studied in a long-term field experiment conducted since 1972 at two sites in the Czech Republic; Pernolec and Hněvčeves. The ongoing trial comprises multi-crop and simple crop rotations with 50 and 75% cereals, respectively. Three herbicide treatments were used: (1) untreated; (2) synthetic auxins (MCPA; 2,4-D; only in simple crop rotation) and (3) targeted herbicide combinations, including especially sulfonylureas, triazines, ureas and synthetic auxins. Weed species composition and weed density were assessed at the trial beginning, during the trial and in the present (2013-2016). Changes in weed flora composition were found out. In Hněvčeves, abundance of some species such as Galium aparine, Stellaria media, and Vicia spp. increased on untreated plots; the abundance of Apera spica-venti, Fumaria officinalis, and Tripleurospermum inodorum increased on treated plots. In Pernolec, some species receded in all variants, e.g. Myosotis arvensis, Raphanus raphanistrum, and Scleranthus annuus; the abundance of Centaurea cyanus, Tripleurospermum inodorum, Veronica spp., and Spergula arvensis increased in untreated plots. No significant differences affected by time and treatment were detected in population densities of Apera spica-venti, Arabidopsis thaliana, and Stellaria media. The species composition of the weed community was affected by explanatory variables in the following order: treatment < time < type of cultivated crop. The longterm study confirmed weed population shifts over time were caused by interaction between the management factors and environmental conditions.

The efficacy and selectivity of herbicides and tank-mix combinations at different application terms in Clearfield and ExpressSun sunflowers were evaluated. Five-plot field trials (2011-2015) were carried out in Prague. The efficacy of tribenuron (TBM) was excellent and quite rapid on Chenopodium album. Its efficacy on other tested dicot weeds ranged around 90%, depending on weather conditions and growth stages of weeds. Echinochloa crus-galli was not controlled by TBM. The tank-mix combination of TBM + propaquizafop (PQF) caused sunflower injury when applied in a very cold growing period. Under dry conditions, PQF efficacy on E. crus-galli was strongly reduced. The split application of TBM, when PQF was used at the second application, was less negatively affected by herbicide antagonisms. Very good results were obtained on plots with pre-emergence treatment with dimethenamid and post-emergence with TBM. The efficacy of imazamox (IZM) on dicot weeds was strongly affected by growth stages of weed and weather conditions during application. Efficacy of IZM on E. crus-galli was increased by oil adjuvant, but this adjuvant reduced IZM selectivity. The best efficacy, selectivity, and Clearfield sunflower yield were on plots with the split application of IZM.

“Arable Weeds and Management in Europe” is a collection of weed vegetation records from arable fields in Europe, initiated within the Working Group Weeds and Biodiversity of the European Weed Research Society (EWRS). Vegetation-plot data from this scientific community was not previously contributed to databases. We aim to prove the usefulness of collection for large scale studies through some first analyses. We hope to assure other weed scientists who have signalled willingness to share data, and plan to construct a full data base, making the data available for easy sharing. Presently, the collection has over 60,000 records, taken between 1996 and 2015. Many more studies for potential inclusion exist. Data originate mostly from studies exploring the effect of agricultural management on weed vegetation. The database is accompanied with extensive meta-data on crop and weed management on the surveyed fields. The criteria for inclusion were a minimum amount of information on the cultivated crop, and a georeference. Most fields were surveyed repeatedly, i.e. transects, multiple random plots, or repeated visits. All surveys aimed to record the complete vegetation on the plots. Sometimes, taxa were identified only to genus level, due to survey dates very early in the vegetation period. Plant taxonomy is standardized to the Euro+Med PlantBase.

Barren brome (Bromus sterilis L.) is a troublesome weed of winter cereals in western and central Europe and its control requires an exact estimation of emergence time. The study focused on the germination response of populations from the Czech Republic to water availability at different temperatures and under different light regimes. Seeds were able to germinate even at very low water potential (Ψ) close to the wilting point, but decreasing temperatures below 25°C and exposure to light decreased the germination percentage (GP) and prolonged the time to reach 50% germination (T50). At higher temperatures of 15, 20, and 25°C, seeds germinated up to a Ψ value of-1.5 MPa; however, the GP differed between light (0-3%) and darkness (50-75%). At the highest temperature of 25°C and germination in water, T50 was less than 1 day, but a decrease in Ψ to -1.5 MPa prolonged the T50 to 5 days; however, this occurred without any significant effect of light regime. With decreasing temperature and Ψ, seeds were more sensitive to the light regime and the disproportion between T50 in light and darkness increased. At a Ψ of less than -1.0 MPa, seeds needed twice as long for germination in light than in darkness when germinating at 20°C or 15°C. The results may be of value for the development of predictive models and for identifying times when weed control may be the most effective.

Neophytes belong to a group of non‑native plants, which were introduced by man either intentionally or unintentionally in different ways. The discovery of America is a historical milestone for non-native plant research. Most scientists use the term neophyte for species introduced after the year 1500. Neophytes became progressively more numerous in arable fields and their proportion significantly increased during the second half of the 20th century. The aim of this study was to assess the occurrence of neophytes in arable fields in the Czech Republic in terms of applied management systems, crops, and environmental site conditions at different altitudes. In the years 2006 to 2008, a phytocoenological survey was conducted on selected farms across the Czech Republic under various climate and soil conditions in spring and winter cereals and in wide‑row crops. Totally, 172 weed species were found. Among these species, 8 % were considered as neophytes (13 species). In respect of their stage of invasiveness, 6 neophytes were considered as invasive, 6 species as naturalized and 1 species was considered as casual. Frequencies of neophyte species we found ranged between 0.3 – 31 % from all relevés. Environmental site conditions associated with altitude were the most important factors correlated with the occurrence of neophytes. The incidence of neophytes is primarily concentrated at lower altitudes and is mainly associated with stands of spring wide‑row crops, especially root crops and vegetables. A higher proportion of neophytes was found in organic farming.

The aim of this study was to explore the composition of weed vegetation on arable land in selected areas of the Czech Republic and to determine the level of γ-diversity. Our survey was conducted at 27 conventional and 35 organic farms from 2006–2008. In each sampled field, one phytocoenological relevé of a standard size of 100 m2 was recorded in the central part of the field. The species cover was estimated. The total γ-diversity was expressed as the total number of weed species recorded. γ-diversity of different farming systems, altitudes and crops was calculated. Subsequently, the species were divided on the basis of their perenniality. In total, 172 weed species were found – 123 and 162 in conventional and organic farming, respectively. The highest number of species was found in winter cereals and at medium altitudes. Chenopodium album was recorded as the species with the highest constancy in both types of farming. In total, 89 annuals, 17 biennials and 15 perennials were observed in conventional farming, and 109 annuals, 23 biennials, 28 perennials and 2 semiparasitic annuals were found in organic farming.

The study was conducted to assess the effect of conventional, integrated and organic management on differences in plant species composition, richness and diversity. The plants were studied in triads of orchards situated in three regions of the Czech Republic. Data about species occurrences were collected on 15 permanent plots in the tree rows and 15 plots between tree rows in each of the apple orchards during 2009. A total of 201 vascular plant species (127 native species, 65 archaeophytes, and 9 neophytes) were found. Management type and also different regional conditions had a significant effect on plant species composition and on diversity parameters of orchard spontaneous vegetation. Species richness and species pool was significantly higher in the organic orchards than in the differently managed orchards. Management type had significant effect on proportions of archaeophytes, and also neophytes in apple orchards. The results showed that a change from conventional to integrated and organic management in apple orchards lead to higher plant species diversity and to changes in plant species composition.

Magnesium complexes of phthalocyanines (Pcs) and their aza-analogues have a great potential in medical applications or fluorescence detection. They are known to demetallate to metal-free ligands in acidic environments, however, detailed investigation of this process and its possible prevention is lacking. In this work, a conversion of lipophilic and water-soluble magnesium complexes of Pcs and tetrapyrazinoporphyrazines (TPyzPzs) to metal-free ligands was studied in relation to the acidity of the environment (organic solvent, water) including the investigation of the role of delivery systems (microemulsion or liposomes) in improvement in their acido-stability. The mechanism of the demetallation in organic solvents was based on an acidoprotolytic mechanism with the protonation of the azomethine nitrogen as the first step and a subsequent conversion to non-protonated metal-free ligands. In water, the mechanism seemed to be solvoprotolytic without any protonated intermediate. The water-soluble magnesium complexes were stable in a buffer with a physiological pH 7.4 while a time-dependent demetallation was observed in acidic pH. The demetallation was immediate at pH < 2 while the full conversion to metal-free ligand was done within 10 min and 45 min for TPyzPzs at pH 3 and pH 4, respectively. Incorporation of lipophilic magnesium complexes into microemulsion or liposomes substantially decreased the rate of the demetallation with the latter delivery system being much more efficient in the protection from the acidic environment. A comparison of two different macrocyclic cores revealed significantly higher kinetic inertness of magnesium TPyzPz complexes than their Pc analogues.