Bromus Sterilis Research Articles

The genome sequence of barren brome, Bromus sterilis L. (Poaceae).

We present a genome assembly from an individual Bromus sterilis (the barren brome; Streptophyta; Magnoliopsida; Poales; Poaceae). The genome sequence has a total length of 2,677.90 megabases. Most of the assembly is scaffolded into 7 chromosomal pseudomolecules. The mitochondrial and plastid genome assemblies have lengths of 523.28 kilobases and 136.96 kilobases, respectively. Gene annotation of this assembly on Ensembl identified 29,147 protein-coding genes.

Laser weed seed control: challenges and opportunities

Farmers are greatly interested in reducing weed seeds in their fields to avoid unnecessary weed infestation. Autonomous vehicles equipped with plant recognition systems and lasers can be used to control weed plants and may therefore be used to replace or supplement herbicides and mechanical weed control. However, less is known about the ability of laser to control weed seeds. In this study, seeds of weeds (Alopecurus myosuroides, Anisantha sterilis, Avena fatua, Centaurea cyanus, Silene noctiflora) and crops (wheat (Triticum aestivum), maize (Zea mays)) were exposed to increasing dosages of laser energy. The species represented dicots and monocots with different seed sizes and morphology. We used a thulium-doped 50 W fiber laser with a wavelength of 2 µm and a diameter of 2 mm developed for weed control. The seeds were exposed to laser directly on the seed surface or after been covered with soil (2.5 and 5 mm). Small doses of energy (0.4 J mm−2 and 0.8 J mm−2) affected the germination ability of small seeds (S. noctiflora and C. cyanus) when the seeds were irradiated directly on the seed surface, and they were completely burned at the high doses (8.0 J mm−2 and 15.9 J mm−2). However, there was not a clear relationship between seed size and sensitivity to laser dose. Additionally, increasing the laser dose on the seed surface resulted in increasing infection of fungi. Seeds covered with soil were not affected by the laser treatments except C. cyanus seeds. Controlling large seeds on the ground while weed seedlings are controlled with laser robots seems realistic in the future. However, dosages higher than 50 J (~15.9 J mm−2) is necessary to control large seeds.

Persistence of Root Exudates of Sorghum bicolor and Solidago canadensis: Impacts on Invasive and Native Species.

Root exudates of the invasive Solidago canadensis and the cereal crop Sorghum bicolor (L.) Moench cv. 'Hybridsorgo' were tested for allelopathic interactions against native and invasive plant species in a controlled environment. After the surface was sterilized, the seeds of two invasive species (Bromus sterilis and Veronica persica) and two native species (Youngia japonica and Rumex acetosa) were germinated and transplanted into the soil (1:1 mixture of coco peat and sand) that had been conditioned for one month by the cultivation of Solidago canadensis and Sorghum bicolor, both in combination or as unplanted controls. After an additional eight weeks of growth, morphometric measurements of the shoot and root, including foliar characteristics and above- and below-ground biomass accumulation, were performed. The results revealed significant inhibitory effects of root exudates released by Sorghum bicolor and Solidago canadensis on native species' productivity and physiology. The invasive species exhibited variable growth responses, with Veronica persica showing reduced shoot and root expansion, but Bromus sterilis revealed increased shoot and root biomass allocation and nutrition under the exudate treatments. Exudates from Solidago canadensis and Sorghum bicolor together showed synergistic negative effects on native species, while they promoted growth and nutrition in Veronica persica. Taken together, the differential species responses indicate that the tested native species were more sensitive to the allelopathic compounds than the invasive species, which is in line with the theory of novel weapons. The legacy effects of root exudates of both Sorghum bicolor and Solidago canadensis could promote invasive establishment through imposing allelochemical interference competition against native plant species. Understanding the specific allelopathic mechanisms may help with the development of integrated strategies for managing invasive species.

Herbicide resistance in Bromus spp.: a global review

AbstractThis review summarizes what is currently known about herbicide resistance in Bromus spp. worldwide. Additional information on the biology and genetics of Bromus spp. is provided to further the understanding of resistance evolution and dispersal of the different species. Cases of herbicide resistance have been confirmed in Bromus catharticus Vahl., Bromus commutatus Schrad. (syn.: Bromus racemosus L.), Bromus diandrus Roth, Bromus japonicus Thunb. (syn.: Bromus arvensis L.), Bromus madritensis L., Bromus rigidus Roth (syn.: Bromus diandrus Roth ssp. diandrus), Bromus rubens L., Bromus secalinus L., Bromus sterilis L., and Bromus tectorum L. in 11 countries. Bromus spp. populations have evolved cross- and multiple resistance to six herbicide sites of action: acetyl-coenzyme A carboxylase, acetolactate synthase, photosystem II, very-long-chain fatty-acid, 5-enolpyruvylshikimate-3-phosphate synthase, and 4-hydroxyphenylpyruvate dioxygenase inhibitors. Resistance mechanisms varied from target-site to non–target site or a combination of both. Bromus spp. are generally highly self-pollinated, but outcrossing can occur at low levels in some species. Bromus spp. have different ploidy levels, ranging from diploid (2n = 2x = 14) to duodecaploid (2n = 12x = 84). Herbicide resistance in Bromus spp. is a global issue, and the spread of herbicide-resistance alleles primarily occurs via seed-mediated gene flow. However, the transfer of herbicide-resistance alleles via pollen-mediated gene flow is possible.

INTERNAL STEM ANATOMY OF SIX BROMUS SPECIES GROWN IN DUHOK PROVINCE, KURDISTAN REGION. IRAQ

The stems of six species of Bromus (B. scoparius L., B. lanceolatus Roth., B. sterilis L., B. madritensis L., B. squarrosus L. and B. danthoniae Trin.) which belongs to Poaceae family grown in Duhok province, Kurdistan region, Iraq were examined anatomically. The samples of Bromus species have been collected from Duhok city in spring 2022. The research was carried out at Biology department, Faculty of science, University of Zakho. The study aims to distinguish between the anatomical differences among the Bromus species since they share phenotypic traits that make it difficult to distinguish them apart. The samples were fixed in formalin- acetic-acid alcohol (FAA) and cross sections were prepared, examined using compound light microscope and photographed at different power. The highest number and measures of the vascular bundles, thicknesses of cuticle, epidermis, hypodermis, and the diameters of the minor and major vascular bundles (stele) were recorded in the B. danthoniae. while, the highest dimeters of metaxylem and cross section of stem were appeared in B. scoparius and B. sterilis, respectively. On the other hand, the lowest number and measures of the above-mentioned features were fluctuated among the Bromus sterilis, B. lanceolatus, B. madritensis. The cross sections indicated that there were valuable differences in both qualitative and quantitative values of the anatomical features among the species.

Effect of weather conditions on efficacy of different herbicides used in Bromus sterilis control

AbstractEfficacy of herbicides is strongly affected by weather conditions shortly before and after application. Small‐plot field trials were carried out in winter wheat in north‐west Bohemia, Czech Republic, Central Europe from 2011 to 2018. The relationship between meteorological characteristics and efficacy of acetolactate synthase inhibiting herbicides (mesosulfuron + iodosulfuron, propoxycarbazone and pyroxsulam) on Bromus sterilis was studied. The effects of precipitation before and after herbicide application, mean temperature and sunshine hours after the application were found to be statistically significant. The total precipitation 30 days before herbicide application had the greatest effect on herbicide efficacy. Mean efficacy significantly increased with increasing precipitation, when mean temperatures 5 days after treatment were above 9°C. The herbicide mesosulfuron + iodosulfuron was most affected by amount of precipitation while efficacy of pyroxsulam was minimally affected. When total rainfall amounted to 30 mm in the 20–40 days after herbicide application, there was no significant effect of total rainfall before herbicide application. In order to prepare the best weed control strategy against B. sterilis, weather conditions before and after the application term should be considered so that the growers can adjust for proper application timing and be prepared for a second application with a suitable herbicide.

Enhanced Lead Phytoextraction by Endophytes from Indigenous Plants

Lead (Pb) is one of the most common metal pollutants in soil, and phytoextraction is a sustainable and cost-effective way to remove it. The purpose of this work was to develop a phytoextraction strategy able to efficiently remove Pb from the soil of a decommissioned fuel depot located in Italy by the combined use of EDTA and endophytic bacteria isolated from indigenous plants. A total of 12 endophytic strains from three native species (Lotus cornicolatus, Sonchus tenerrimus, Bromus sterilis) were isolated and selected to prepare a microbial consortium used to inoculate microcosms of Brassica juncea and Helianthus annuus. As for B. juncea, experimental data showed that treatment with microbial inoculum alone was the most effective in improving Pb phytoextraction in shoots (up to 25 times more than the control). In H. annuus, on the other hand, the most effective treatment was the combined treatment (EDTA and inoculum) with up to three times more Pb uptake values. These results, also validated by the metagenomic analysis, confirm that plant-microbe interaction is a crucial key point in phytoremediation.

Identification of the most suitable reference gene for gene expression studies with development and abiotic stress response in Bromus sterilis

Bromus sterilis is an annual weedy grass, causing high yield losses in winter cereals. Frequent use of herbicides had led to the evolution of herbicide resistance in this species. Mechanisms underlying herbicide resistance in B. sterilis must be uncovered because this problem is becoming a global threat. qRT-PCR and the next-generation sequencing technologies can elucidate the resistance mechanisms. Although qRT-PCR can calculate precise fold changes, its preciseness depends on the expression of reference genes. Regardless of stable expression in any given condition, no gene can act as a universal reference gene. Hence, it is necessary to identify the suitable reference gene for each species. To our knowledge, there are no reports on the suitable reference gene in any brome species so far. Thus, in this paper, the stability of eight genes was evaluated using qRT-PCR experiments followed by expression stability ranking via five most commonly used software for reference gene selection. Our findings suggest using a combination of 18S rRNA and ACCase to normalise the qRT-PCR data in B. sterilis. Besides, reference genes are also recommended for different experimental conditions. The present study outcomes will facilitate future molecular work in B. sterilis and other related grass species.

Enhanced metabolism and target gene overexpression confer resistance against acetolactate synthase-inhibiting herbicides in Bromus sterilis.

Intensive application of acetolactate synthase (ALS)-inhibiting herbicides has resulted in herbicide-resistance in many weeds, including Bromus sterilis. The present study was conducted to identify the mechanisms conferring resistance to ALS-inhibiting herbicides in a Bromus sterilis biotype. Dose-response studies revealed the resistant biotype to be 288 times less sensitive to pyroxsulam than the susceptible biotype. Furthermore, experiment with a single-dose, proved this biotype was also cross-resistant to propoxycarbazone, iodosulfuron plus mesosulfuron and sulfosulfuron. Prior treatment with malathion, a known inhibitor of cytochrome P450s, reduced the level of resistance to pyroxsulam. No mutations were detected from the partial ALS gene sequencing. Flow cytometry and chromosome counting rejected ploidy level variation between the susceptible and resistant biotypes. Relative copy number variation ruled out gene amplification. Quantitative real-time polymerase chain reaction (PCR) detected a significant difference in ALS gene expression between the susceptible and resistant biotypes. Target gene overexpression and enhanced metabolism by cytochrome P450s are likely mechanisms of resistance to pyroxsulam in Bromus sterilis. The current findings highlight the need to monitor additional brome populations for herbicide resistance in Europe and endorse the need for alternate herbicides in integrated weed management to delay the possible evolution of herbicide resistance in these species. © 2020 Society of Chemical Industry.

Grass pollen morphology investigation as a basis for monitoring of allergenic biological particles in an automatic mode

A clear distinction between the morphology of allergenic pollen grains of various genera of the Poaceae family is an important task in determining the causal allergenic factors in the population. It allows significant improvement of the efficiency of seasonal allergy diagnostics caused by grass pollen. Moreover, it let to perform better predictions of allergenic risks for people, suffering from pollinosis caused by Poaceae pollen. Therefore, the aim of our study was to establish the morphological difference between the pollen grains of plants of various species of Poaceae family in order to further determination of the possibility to use the established distinctions for the identification of pollen in aerobiological studies. For this, both herbarium samples and pollen of the studied plants were collected in the field during May-June 2019 in Vinnytsia. The pollen was shaken off the anthers directly onto a glass slide, immediately stained with basic fuchsin, and covered with a cover slip. The sizes of pollen grains – their width and length – were determined and analyzed using the PhotoM 1.21 program, and the obtained data on the sizes of pollen were divided into categories by the quartile method in Excel. Three categories of pollen sizes were identified: large, medium and small. Large grains had width and length parameters of 40 μm or more, average grains ranged from 26 to 39 μm, and small grains had a size of 26 μm or lesser in width and length. The large category includes the pollen of Hordeum morinum (39.5-53.1 μm), Elytrigia repens (41-48 μm), Secale cereale (48.4-62.5 μm) and Bromus arvensis (42.2-52.7 μm). The medium grain category included pollen from Dactylis glomerata (29.2-38.1 μm), Poa spp. (26.1-37.3 μm), Panicum capillare (33.3-39.5 μm), Lolium perenne (30.4-35.3 μm), Bromus sterilis (28.3-30.8 μm). The pollen size of B. ramosus ranged from 26.1 to 39.5 µm, and B. tectorum was from 35 to 38.4 µm. The pollen grains of Poa pratense (22.1-25.9 μm) and Piptatherum spp were assigned to the category of the smallest pollen (20.3-24.1 microns). Agrostis gigantea was the only grass pollen type whose size fitted for each category. We found out large, medium-sized and grains of 25.0-27.7 microns, which lie between categories 2 and 3, for different populations of this plant. Consequently, some genera and species of Poaceae can be distinguished by the size of their pollen, while in others the size of pollen grains varies considerably. It is necessary to carry out further research that will help to establish the morphology of pollen of a larger number of Grass family plants. This will significantly improve the diagnosis and prevention of seasonal allergy caused by grass pollen in Ukraine.

Trophic level and basal resource use of soil animals are hardly affected by local plant associations in abandoned arable land.

Plants provide resources and shape the habitat of soil organisms thereby affecting the composition and functioning of soil communities. Effects of plants on soil communities are largely taxon‐dependent, but how different functional groups of herbaceous plants affect trophic niches of individual animal species in soil needs further investigation. Here, we studied the use of basal resources and trophic levels of dominating soil meso‐ and macrofauna using stable isotope ratios of carbon and nitrogen in arable fallow systems 3 and 14–16 years after abandonment. Animals were sampled from the rhizosphere of three plant species of different functional groups: a legume (Medicaco sativa), a nonlegume herb (Taraxacum officinale), and a grass (Bromus sterilis). We found virtually no consistent effects of plant identity on stable isotope composition of soil animals and on thirteen isotopic metrics that reflect general food‐web structure. However, in old fallows, the carbon isotope composition of some predatory macrofauna taxa had shifted closer to that of co‐occurring plants, which was particularly evident for Lasius, an aphid‐associated ant genus. Trophic levels and trophic‐chain lengths in food webs were similar across plant species and fallow ages. Overall, the results suggest that variations in local plant diversity of grassland communities may little affect the basal resources and the trophic level of prey consumed by individual species of meso‐ and macrofauna belowground. By contrast, successional changes in grassland communities are associated with shifts in the trophic niches of certain species, reflecting establishment of trophic interactions with time, which shapes the functioning and stability of soil food webs.

Relationship between broadleaved mixed forest understory species groups with soil and elevation in a semi-arid Persian oak (Quercus brantii L.) ecosystem

This research aimed to investigate the relationship between plant composition of Dinarkooh Protected Area (DPA), west of Iran (called Zagros forests) with elevation and soil properties. A total of 100 random sampling plots (25 × 25 m) at different elevations were sampled for their soil and collection of plant specimens and vegetation data based on Braun-Blanquet covered-abundance scale. Data were analyzed using TWINSPAN and multivariate statistical analysis packages. We recognized 142 plant species present in the study area identified under 105 genera and 29 families. Asteraceae, Papilionaceae and Poaceae were the most frequently encountered families. Bromus and Astragalus were also the largest genera in the study area. The plant species were grouped into three ecological groups based on elevation and soil properties: Group 1 with 20 species including Scorzonera sp. and Cerastium inflatum L. at lower elevation (1300-1500 m a.s.l.) and with clay-loam soil; Group 2 with 96 species, including Onosma trachytrichum Boiss., Eryngium noeanum Boiss. and Acer monspessulanum L. occurred at middle elevations with alkaline loam-clay soil; and Group 3 with 26 species, including Bromus sterilis L., Minuartia meyeri, Minuartia meyeri (Boiss.) Bornm., Lithospermum sp., Scariola orientalis (Boiss.) Sojak and Trifolium tomentosum L. at higher elevation with sandy-loam soil. Prevalent tree species included Oak (Quercus brantii Lindl. var. persica (Jaub. & Spach)) in Group 2 and Acer monspessulanum L. in Group 3. Low homogeneity of plant compositions at different elevations reflects the differences in habitat properties. Results showed that the elevation and soil properties played primary and complementary roles in vegetation spatial composition. Furthermore, diversity and richness of plant species was higher at middle elevations. More detailed investigation into biotic variables at the root level would complement current data to analyze this ecosystem.

Modelling annual grass weed seed dispersal in winter wheat, when influenced by hedges and directional wind

Accurate predictions of weed seed dispersal are important for spatial modelling of weed population dynamics. However there are few multi-year data sets available, and they are seldom analysed well. Here we gathered together and re-examined population growth and seed spread data from three grass weed species over 3 years. Using a new seed spread function in the simulation model SOMER it was possible to accurately parametrise population growth and seed spread to replicate the field data of Apera spica-venti (APESV) and Bromus sterilis (BROST). In contrast, the greatest increases in Alopecurus myosuroides (ALOMY) numbers occurred in the direction of machinery movement, which could not be predicted using this function. A probability-sum, exponential-type function gave an excellent fit to the field data for APESV and BROST, with changes in seed spread distances due to species differences, wind, and ‘shading’ from the hedge, accommodated by alterations in the scale, shape, and wind dispersal parameters. Here we describe a method of parametrising the probability function from within a stochastic simulation. Working within the simulation allowed empirical population size data sets to be successfully parameterised, without mathematical integration. This function is fully explained with stochastic simulated examples, and fitted to various two-dimensional longitudinal data sets. Enough detail to enable its parametrisation (including simplification) within a majority of spatial stochastic population models is included.

Occurrence of new case-bearer on cereals, Coleophora perplexella Toll, 1960 (Lepidoptera: Coleophoridae)

Coleophora perplexella Toll, 1960 it is native of Spain and Portugal, but it has detected out of its origin area, and was found in Sardinia, Morocco and Algeria without its host plant being identified. Recently has been observed in France (Toulon) on Hordeum murinum L. and Bromus sterilis L. (Poaceae). However, it was never cited among the Tunisian entomofauna. In addition, C. perplexella was never known as agricultural pest in its area or elsewhere. Moreover, no deep studies diagnosis and biology were conducted. This paper is a first study on C. perplexella, detected as an agricultural pest on oat (Avena sativa L., 1753) and barely (Hordeum vulgare L., 1753) making serious damages on early seedlings. Besides, a description and illustrations of different biological stage was provided. Results highlight a difference between the appearance dates of emerged new adults under both controlled and ambient conditions. According these results we can conclude on adaptation plasticity to the environmental conditions. In fact, C. perplexella can survive and cause damage at temperature between 7-10º C from December to February, and 23-25º C of controlled conditions.

Alien invasive as well as rare and endangered species in the agrocenoses of the Ułęż commune

The paper analyses the presence of invasive alien species and rare taxons among crop weeds in the Ułęż commune. The study is based on phytosociological relevés taken according to the Braun-Blanquet method. In total, 99 phytosociological relevés were taken. The research was conducted in 2016 and 2017. Ten rare regional and cross-regional species were found among weeds in cultivated crops. These were: Agrostemma githago, Arnoseris minima, Avena strigosa, Chenopodium polyspermum, Consolida regalis, Veronica opaca, Veronica polita, Veronica agrestis, Bromus secalinus, and Centaurea cyanus. Some of the most common species in that area included Centaurea cyanus and Bromus secalinus, while Avena strigosa also belonged to frequent components of the local flora. Other species were recorded rarely or very rarely. Additionally, in the crops, there was a group of 16 invasive alien species. Setaria pumila had the largest vegetal cover and the largest number of positions. There were some more frequently recorded species like Echinochloa crus-galli, Galinsoga parviflora and Conyza canadensis, with Avena fatua being quite common as well. Other species quite often found were: Amaranthus retroflexus, Galinsoga ciliata, Veronica persica and Oxalis fontana. However, species such as Setaria viridis, Solidago canadensis, Bidens frondosa, Epilobium ciliatum, Alopecurus myosuroides, Bromus sterilis and Parthenocissus inserta were rarely or very rarely found in the crops.

The First Cases of Evolving Glyphosate Resistance in UK Poverty Brome (Bromus sterilis) Populations

AbstractPoverty brome (Bromus sterilisL.) [sterile or barren brome, syn.Anisantha sterilis(L.) Nevski] is a problematic UK arable weed. There are currently no confirmed cases of glyphosate resistance in any weed species in the United Kingdom or inB. sterilisworldwide. However, there are reports of poor control by glyphosate in this species. Here, we report experiments to confirm the suspected on-farm resistance ofB. sterilispopulations to glyphosate. Glyphosate screening and dose–response experiments established that glyphosate sensitivity of three UKB. sterilispopulations exhibiting poor field control is outside the normal range of sensitivity of 30 sensitive populations and adjacent unexposed populations. Control of sensitive populations ranged from 49% to 82% and for suspected resistant populations from 21% to 30%. Dose–response ED50values of sensitive populations ranged between 241 and 313 g ai ha−1; corresponding values of suspected resistant populations ranged between 420 and 810 g ha−1, and resistance indices ranged from 1.55 to 4.5. Suspected resistant populations were incompletely controlled at the recommended field rate of glyphosate (540 g ha−1), while adjacent unexposed populations were completely controlled. We conclude that some UK populations ofB. sterilishave reduced glyphosate sensitivity and are in the process of evolving resistance. This is the first reported case of reduced glyphosate sensitivity in any UK weed species and inB. sterilisworldwide. This, coupled with increasing glyphosate use, highlights the need for increased vigilance and monitoring for glyphosate resistance in the United Kingdom.

Effects of drought on weed emergence and growth vary with the seed burial depth and presence of a cover crop

In conservation agriculture, weed seed germination could decrease with the presence of a cover crop, surface weed seed location and temporal drought in summer just after seed shedding. This study simultaneously examined the effects of a cover crop, burial depth (seed location) and hydric stress on weed emergence and early growth. It was hypothesized that drought would reduce weed emergence and the initial growth of weed seeds and that this effect would be greater when the seeds were on the soil surface and in the presence of a cover crop. Four annual weed species were chosen that are frequently found (Anisantha sterilis, Vulpia myuros, Sonchus asper, Veronica persica) and not frequently found (Alopecurus myosuroides, Poa annua, Cyanus segetum, Capsella bursa‐pastoris) in fields that implement conservation agriculture. The unburied seeds had 26% lower emergence, on average, than the buried seeds (significant for six of the eight species), hydric stress reduced emergence by 20% (for seven of the eight species) and the presence of a cover crop reduced the level of emergence by 17% (for all species). The unburied seeds with hydric stress were emerging under the “most stressful” set of factors, with a 45% decrease in emergence, compared with the seeds emerging under the “least stressful” set of factors (buried seeds without hydric stress). All the weed growth measurements (height, dry matter content and number of leaves) decreased with the presence of a cover crop. The species that are found frequently in the fields that implement conservation agriculture, compared with the species that are not frequently found in conservation agriculture fields, had higher rates of germination and a higher tolerance of hydric stress when their seeds were unburied.

Germination responses to water potential in Bromus sterilis L. under different temperatures and light regimes

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 (T<sub>50</sub>). 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, T<sub>50</sub> was less than 1 day, but a decrease in Ψ to –1.5 MPa prolonged the T<sub>50</sub> to<br /> 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 T<sub>50</sub> 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.

Effects of adjuvants and carriers on propoxycarbazone and pyroxsulam efficacy on Bromus sterilis in winter wheat

Effects of adjuvants and carriers on propoxycarbazone and pyroxsulam efficacy on Bromus sterilis in winter wheat

Seasonal Changes in Leaf Tissue Rehydration of One Annual and Two Perennial Grass Forage Species Induced by Bioclimate

Bioclimate signifies the continuous interplay between plants and climate factors (primarily drought) and has a direct impact on the water relations and the duration of the rehydration process in water stressed plants. To explore the association between bioclimate and water physiology of forage species in semi-arid Mediterranean grasslands, we determined the seasonal variation in leaf water potential, turgid weight and relative water content in wild growing Dactylis glomerata L., Bromus inermis Leyss (perennial) and Bromus sterilis L. (annual) during the growing season. The study was conducted at the farm of the Aristotle University of Thessaloniki. The results of the current study reveal that B. sterilis maintained high levels of water potential most probably by accelerating its biological cycle and decreasing water content because it fails to sustain turgidity. Dactylis glomerata and B. inermis presented even higher water contents than B. sterilis for the same water potential. Dactylis glomerata exhibited substantially higher water potential and content than B. inermis by keeping the rehydration duration stable. The extensive creeping rhizome seems to allow B. inermis to sustain high values of water potential and content possibly ensuring turgidity. Regardless of the grass species the duration of rehydration ranged from 2.5 to 3.5 hours throughout the growing season. Our findings demonstrate that (a) D. glomerata and B. inermis are better adapted to Mediterranean semiarid conditions than B. sterilis and (b) turgid weight in Mediterranean forage species can safely be determined after a rehydration period of 3.5 hours.