Effect of osmotic potential and temperature on germination of kochia (\u3ci\u3eBassia scoparia\u3c/i\u3e) populations from the U.S. Great Plains

Development of integrated weed management strategies requires knowledge of weed emergence timing and patterns, which are regulated primarily by water and thermal requirements for seed germination. Laboratory experiments were conducted in fall 2017 to fall 2018 to quantify the effect of osmotic potential and temperature on germination of 44 kochia [Bassia scoparia (L.) A.J. Scott] populations under controlled conditions. Bassia scoparia populations were collected in fall 2016 from northern (near Huntley, MT, and Powell, WY) and southern (near Lingle, WY, and Scottsbluff, NE) regions of the U.S. Great Plains. Ten osmotic potentials from 0 to −2.1 MPa and eight constant temperatures from 4 to 26 C were evaluated. Response of B. scoparia populations to osmotic potential did not differ between the northern and southern regions. At an osmotic potential of 0 MPa, all B. scoparia populations had greater than 98% germination, and the time to achieve 50% germination (t50) was less than 1 d. At −1.6 MPa, 25% of seeds of all B. scoparia populations germinated. Osmotic potentials of −0.85 and −1.9 MPa reduced B. scoparia germination by 10% and 90%, respectively. Regardless of temperature regime, all populations exhibited greater than 88% germination. The germination rate was highest at temperatures between 15 to 26 C and did not differ between populations from northern versus southern regions. At this temperature range, all populations had a t50 of less than 1 d. However, at 4 C, B. scoparia populations from the northern region had a higher germination rate (5 h) and cumulative germination (7%) than populations from the southern region. Overall, these results indicate a wide range of optimum temperatures and osmotic potential requirements for B. scoparia germination

Eradication of Exotic Weeds in Australia: Comparing Effort and Expenditure

Weeds have many adverse impacts on agriculture and the environment and therefore are often targets of eradication attempts. Eradication attempts involve large commitments of labour and financial resources over significant periods of time. Using data from 12 Australian weed eradication attempts the authors compare work hours and expenditure on each attempt for various initial-infestation sizes. Analysis of a limited data set shows: (1) that while the eradication effort increases with the initial area of infestation, the effort applied per hectare actually decreases; (2) that application of a greater work effort was not the reason why completed eradications were successful; and (3) that the larger the initial infestation size, the smaller the amount of resources applied per hectare for eradication.weeds, eradication, work effort, expenditure, infestation size, Environmental Economics and Policy, Resource /Energy Economics and Policy,

Plants traditionally used to make brooms in several European countries

<p>Abstract</p> <p>Background</p> <p>The research was carried out within the course of two years (2005–2006) in four countries from southern, southeast and eastern parts of Europe: Bulgaria, Italy, Macedonia and Romania. The data are collected mainly from Bulgaria and Italy and are compared with those from Macedonia and Romania.</p> <p>Methods</p> <p>The information was gathered largely from literature as well as field collected data and interviewed informants. A brief questionnaire, referring to the vernacular name, plant description, providing specimens from the plants and brooms, details on their use has been prepared and applied.</p> <p>Results</p> <p>The total number of species as brooms in the study areas is about 108. The list includes two fungi taxa which caused the so-called "Witches' brooms". A high species diversity of 106 taxa of vascular plants, belonging to 37 families and 74 genera, is established in the research area. The investigation includes data about scientific name, family, vernacular name, life form, status (wild or cultivated), used parts and place of use. The relations between the plant characteristics and broom specific shape and working qualities, details of the traditionally broom planting and making, the broom as a part of folklore, traditions and religious rituals are discussed.</p> <p>Conclusion</p> <p>Collected data show how ecological, geographical features and different cultures are related with the variety of plants traditionally used as brooms as well as details for their uses. The data about the variety of plants traditionally used to make brooms and the ways in which they are used according to the specific characteristics of the areas are important for ethnobotanical knowledge.</p

Genomic-based epidemiology reveals independent origins and gene flow of glyphosate resistance in Bassia scoparia populations across North America

Genomic-based epidemiology can provide insight into the origins and spread of herbicide resistance mechanisms in weeds. We used kochia (Bassia scoparia) populations resistant to the herbicide glyphosate from across western North America to test the alternative hypotheses that (i) a single EPSPS gene duplication event occurred initially in the Central Great Plains and then subsequently spread to all other geographical areas now exhibiting glyphosate-resistant kochia populations or that (ii) gene duplication occurred multiple times in independent events in a case of parallel evolution. We used qPCR markers previously developed for measuring the structure of the EPSPS tandem duplication to investigate whether all glyphosate-resistant individuals had the same EPSPS repeat structure. We also investigated population structure using simple sequence repeat markers to determine the relatedness of kochia populations from across the Central Great Plains, Northern Plains and the Pacific Northwest. We found that the original EPSPS duplication genotype was predominant in the Central Great Plains where glyphosate resistance was first reported. We identified two additional EPSPS duplication genotypes, one having geographical associations with the Northern Plains and the other with the Pacific Northwest. The EPSPS duplication genotype from the Pacific Northwest seems likely to represent a second, independent evolutionary origin of a resistance allele. We found evidence of gene flow across populations and a general lack of population structure. The results support at least two independent evolutionary origins of glyphosate resistance in kochia, followed by substantial and mostly geographically localized gene flow to spread the resistance alleles into diverse genetic backgrounds

Seed Germination Responses to Seasonal Temperature and Drought Stress Are Species‐Specific but Not Related to Seed Size in a Desert Steppe: Implications for Effect of Climate Change on Community Structure

Investigating how seed germination of multiple species in an ecosystem responds to environmental conditions is crucial for understanding the mechanisms for community structure and biodiversity maintenance. However, knowledge of seed germination response of species to environmental conditions is still scarce at the community level. We hypothesized that responses of seed germination to environmental conditions differ among species at the community level, and that germination response is not correlated with seed size. To test this hypothesis, we determined the response of seed germination of 20 common species in the Siziwang Desert Steppe, China, to seasonal temperature regimes (representing April, May, June, and July) and drought stress (0, −0.003, −0.027, −0.155, and −0.87 MPa). Seed germination percentage increased with increasing temperature regime, but Allium ramosum, Allium tenuissimum, Artemisia annua, Artemisia mongolica, Artemisia scoparia, Artemisia sieversiana, Bassia dasyphylla, Kochia prastrata, and Neopallasia pectinata germinated to \u3e60% in the lowest temperature regime (April). Germination decreased with increasing water stress, but Allium ramosum, Artemisia annua, Artemisia scoparia, Bassia dasyphylla, Heteropappus altaicus, Kochia prastrata, Neopallasia pectinata, and Potentilla tanacetifolia germinated to near 60% at −0.87 MPa. Among these eight species, germination of six was tolerant to both temperature and water stress. Mean germination percentage in the four temperature regimes and the five water potentials was not significantly correlated with seed mass or seed area, which were highly correlated. Our results suggest that the species‐specific germination responses to environmental conditions are important in structuring the desert steppe community and have implications for predicting community structure under climate change. Thus, the predicted warmer and dryer climate will favor germination of drought‐tolerant species, resulting in altered proportions of germinants of different species and subsequently change in community composition of the desert steppe

Noves aportacions al coneixement de la flora vascular de les comarques meridionals de Catalunya. III

Es comenten un total de 63 tàxons. Allium ampeloprasum L. subsp. pardoi (Loscos) O. Bolòs & Vigo, Bassia scoparia (L.) Voss. subsp. scoparia, Primula × ternovania A. Kerner, Sternbergia colchiciflora Waldst. & Kit. i Vulpia geniculata (L.) Link constitueixen novetats per a la flora de Catalunya, i nou tàxons [Agrostis schleicheri Jord. & Verl., Athyrium filix-femina (L.) Roth, Carex demissa Hornem., Centaurea montana L. subsp. semidecurrens (Jord.) O. Bolòs & Vigo, Dryopteris affinis (Lowe) Fraser-Jenk. subsp. affinis, Myricaria germanica (L.) Desv., Phalaris aquatica L., Trifolium bocconei Savi i Vicia narbonensis L.] suposen novetats per a les comarques meridionals de Catalunya. D'altra banda s'exclou la presència a Catalunya de Lythrum baeticum Gonz.-Albo.Data about 63 taxa are presented. Allium ampeloprasum L. subsp. pardoi (Loscos) O. Bolòs & Vigo, Bassia scoparia (L.) Voss. subsp. scoparia, Primula × ternovania A. Kerner, Sternbergia colchiciflora Waldst. & Kit., and Vulpia geniculata (L.) Link are a new record for the Catalan flora, and nine taxa [Agrostis schleicheri Jord. & Verl., Athyrium filix-femina (L.) Roth, Carex demissa Hornem., Centaurea montana L. subsp. semidecurrens (Jord.) O. Bolòs & Vigo, Dryopteris affinis (Lowe) Fraser-Jenk. subsp. affinis, Myricaria germanica (L.) Desv., Phalaris aquatica L., Trifolium bocconei Savi and Vicia narbonensis L.] are new records for Southern Catalonia. The presence of Lythrum baeticum Gonz.-Albo in Catalonia is excluded

Droplet Size Impact on Efficacy of a Dicamba-plus-Glyphosate Mixture

Chemical weed control remains a widely used component of integrated weed management strategies because of its cost-effectiveness and rapid removal of crop pests. Additionally, dicamba-plus-glyphosate mixtures are a commonly recommended herbicide combination to combat herbicide resistance, specifically in recently commercially released dicamba-tolerant soybean and cotton. However, increased spray drift concerns and antagonistic interactions require that the application process be optimized to maximize biological efficacy while minimizing environmental contamination potential. Field research was conducted in 2016, 2017, and 2018 across three locations (Mississippi, Nebraska, and North Dakota) for a total of six site-years. The objectives were to characterize the efficacy of a range of droplet sizes [150 μm (Fine) to 900 μm (Ultra Coarse)] using a dicamba-plus-glyphosate mixture and to create novel weed management recommendations utilizing pulse-width modulation (PWM) sprayer technology. Results across pooled site-years indicated that a droplet size of 395 μm (Coarse) maximized weed mortality from a dicamba-plus-glyphosate mixture at 94 L ha–1. However, droplet size could be increased to 620 μm (Extremely Coarse) to maintain 90% of the maximum weed mortality while further mitigating particle drift potential. Although generalized droplet size recommendations could be created across site-years, optimum droplet sizes within each site-year varied considerably and may be dependent on weed species, geographic location, weather conditions, and herbicide resistance(s) present in the field. The precise, site-specific application of a dicamba-plus-glyphosate mixture using the results of this research will allow applicators to more effectively utilize PWM sprayers, reduce particle drift potential, maintain biological efficacy, and reduce the selection pressure for the evolution of herbicide-resistant weeds

Halophyte Resilience to Roadside Salinity in Urban Southeastern Michigan

For the past 70 years, municipalities in southeastern Michigan have used chloride as a deicer in winter months. This has resulted in increasing soil salinity and halophytes (salt tolerant plants) proliferating along roadsides. Three halophytes that have taken root in Michigan are common mugwort (Artemisia vulgaris), Bassia scoparia, and seaside goldenrod (Solidago sempervirens) were studied along with Canada goldenrod (Solidago canadensis) as a control. Roadside soil was collected to measure its sodium content, texture, moisture content, organic matter content, and pH. The sodium content of the halophytes stems, roots leaves, secondary stems, fruits, and flowers were also measured. Results have demonstrated all three species have adapted to saline environments as includer halophytes. The perennials seaside goldenrod and common mugwort were found to have contained more sodium than the annual Bassia scoparia. Sequestered sodium was highest in the leaves and stem of the seaside goldenrod, the secondary stems of common mugwort, and the fruit or leaves of Bassia scoparia. Soil sodium content was highest at soil by highways and lowest in residential areas. Additionally, salinity is affected by moisture content and soil texture. Lastly, the sodium content of plants increases with soil salinity. Halophyte sodium content was highest in those collected from roadsides while halophytes growing in soil with no to little salt contain no or little sodium as well. Common mugwort was found growing in soil with the highest salinity measured, seaside goldenrod the second most, and Bassia scoparia the least.MSEnvironmental Science, College of Arts, Sciences, & LettersUniversity of Michigan-Dearbornhttp://deepblue.lib.umich.edu/bitstream/2027.42/169160/1/John Fennessey Final Thesis.pd

Vegetation response to invasive Tamarix control in southwestern U.S. rivers: a collaborative study including 416 sites

Most studies assessing vegetation response following control of invasive Tamarix trees along southwestern U.S. rivers have been small in scale (e.g., river reach), or at a regional scale but with poor spatial-temporal replication, and most have not included testing the effects of a now widely used biological control. We monitored plant composition following Tamarix control along hydrologic, soil, and climatic gradients in 244 treated and 172 reference sites across six U.S. states. This represents the largest comprehensive assessment to date on the vegetation response to the four most common Tamarix control treatments. Biocontrol by a defoliating beetle (treatment 1) reduced the abundance of Tamarix less than active removal by mechanically using hand and chain-saws (2), heavy machinery (3) or burning (4). Tamarix abundance also decreased with lower temperatures, higher precipitation, and follow-up treatments for Tamarix resprouting. Native cover generally increased over time in active Tamarix removal sites, however, the increases observed were small and was not consistently increased by active revegetation. Overall, native cover was correlated to permanent stream flow, lower grazing pressure, lower soil salinity and temperatures, and higher precipitation. Species diversity also increased where Tamarix was removed. However, Tamarix treatments, especially those generating the highest disturbance (burning and heavy machinery), also often promoted secondary invasions of exotic forbs. The abundance of hydrophytic species was much lower in treated than in reference sites, suggesting that management of southwestern U.S. rivers has focused too much on weed control, overlooking restoration of fluvial processes that provide habitat for hydrophytic and floodplain vegetation. These results can help inform future management of Tamarix-infested rivers to restore hydrogeomorphic processes, increase native biodiversity and reduce abundance of noxious species

Micromorphology and leaf ecological anatomy of Bassia halophyte species (Amaranthaceae) from Iran

Bassia belongs to the family Chenopodiaceae, which is widely distributed in the world, especially in Irano-Turanian Region. According to the morphological similarities among the species of the genus, ecological implications of structural features were studied. In fact, understanding these relationships is of great importance in natural classification. We have studied the relationships of Bassia species using morphological, anatomical, and micro-morphological methods. The current results indicated that phenotypic plasticity and repetitive patterns were probably due to ecological adaptations, especially in decreasing the leaf surface by changing the inner structure. All species have a Kranz anatomy structure (Kochioid subtype), related to C4 photosynthesis. The changes in cell size increasing the cell membrane thickness, the density of two-vascular systems, the increase of palisade to water storage parenchyma ratio and photosynthetic system. The leaf surface is covered with long highly dense hairs and microechinate ornamentation. Though the adaptation caused some morphological similarities, the variation was seen in other descriptive characteristics such as morphological and anatomical features especially in two synonym species of B. turkestanica and B. pilosa. Information about the similarity species is provided