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Weed science plays a vital role in mitigating the negative impacts of weeds in agriculture and natural ecosystems. However, the field has received criticism for its limited theoretical foundation and excessive focus on phenomenological and narrow scope. Our contention is that weed science needs to integrate more ecological theories to foster a deeper understanding of weed ecology, biology, and management. By embracing theoretical frameworks, weed science can enhance its ability to predict and explain weed dynamics, identify underlying mechanisms, and develop sustainable management strategies. This insight emphasizes the advantages of integrating theoretical approaches and offers practical recommendations to integrate ecological theory effectively into weed science research. [ABSTRACT FROM AUTHOR]

Current study hypothesized that dietary l‐carnitine (LC) inclusion during the mating period ameliorates both metabolic status and reproductive performance of ewes. Seventy Baluchi ewes (52 ± 4.2 kg of bodyweight and 18 ± 6 months old of age) were enrolled in this study. Animals were randomly allocated into two dietary treatments, control (only basal diet) or basal diet plus supplementation with a rumen‐protected LC (Carneon 20 Rumin‐pro; 20% LC; Kaesler Nutrition GmbH) at the rate of 10 g/head/day from 21 days before until 35 days after introducing rams to the ewes (MP). Feed intake was monitored by subtracting the ort from feed offered. Blood sample collection was conducted on Days −10, +10 and +20 relative to MP. Pregnancy was confirmed on Day 30 post‐MP. Feed intake of the ewes in the LC group was higher than the control (p < 0.05). LC supplementation increased the cholesterol concentration in the ewes (p < 0.05). Blood urea concentration of animals in the LC group was significantly lower than the control (p < 0.05). The mRNA expression of toll‐like receptor 4 was evidently lower in animals supplemented with LC than the control (p < 0.05). Both lambing and fecundity rates in the LC group tended to be higher compared with the control. LC supplementation showed potential to alter certain metabolites in the ewes. A tendency for higher lambing rate may partly be driven by dams efficient energy partitioning to support foetal growth and maintaining pregnancy. [ABSTRACT FROM AUTHOR]

Premise: Characterizing the developmental processes in the transition from hermaphroditism to unisexuality is crucial for understanding floral evolution. Amaranthus palmeri, one of the most devastating weeds in the United States, is an emerging model system for studying a dioecious breeding system and understanding the biological traits of this invasive weed. The objectives of this study were to characterize phases of flower development in A. palmeri and compare organogenesis of flower development in female and male plants. Methods: Flower buds from male and female plants were dissected for light microscopy. Segments of male and female inflorescences at different stages of development were cut longitudinally and visualized using scanning electron microscopy. Results: Pistillate flowers have two to three styles, one ovary with one ovule, and five obtuse tepals. Staminate flowers have five stamens with five acute tepals. Floral development was classified into 10 stages. The distinction between the two flower types became apparent at stage four by the formation of stamen primordia in staminate flowers, which developed female and male reproductive organs initially, as contrasted to pistillate flowers, which produced carpel primordia only. In staminate flowers, the putative carpel primordia changed little in size and remained undeveloped. Conclusions: Timing of inappropriate organ termination varies across the two sexes in A. palmeri. Our study suggests that the evolution of A. palmeri from a cosexual ancestral state to complete dioecy is still in progress since males exhibited transient hermaphroditism and females produced strictly pistillate flowers. [ABSTRACT FROM AUTHOR]

Premise: Understanding recruitment processes of invasive species is central to conservation and management strategies. Iris pseudacorus, an emergent macrophyte, has established invasive populations across a broad global range, and reduces biodiversity in wetland ecosystems. Climate change is altering germination cues, yet studies on the invasion of wetland macrophytes often ignore germination ecology despite its importance to their establishment and spread. Methods: We explored germination of seeds from invasive I. pseudacorus populations in California in response to seed coat presence or absence, and several environmental factors. Using experimental results in a thermal time model, we derived germination temperature thresholds. Results: Germination of I. pseudacorus seeds did not require cold or warm stratification, and was not affected by seed coat presence or absence. Germination occurred in the dark, although germinability was two‐ to threefold times greater under light. At constant temperature, thermal time model estimates included 18.3 ± 1.8°C base germination temperature (Tb $({T}_{b}$); 28.2 ± 0.5°C optimal temperature (To $({T}_{o}$); and 41.0 ± 1.7°C ceiling temperature (Tc $({T}_{c}$). Seeds exposed to 36.0°C achieved over 10% germination, and embryos of ungerminated seeds presented 76% viability. Overall, germinability remained relatively low at constant temperatures (≤25%) but was close to 90% under alternating daily temperatures. Conclusions: Exposure to diurnally fluctuating temperatures is essential for this species to achieve high germination rates. Our study reveals that I. pseudacorus has a broad germination niche supporting its establishment in a relatively wide range of environments, including at high temperatures more frequent with climate change. [ABSTRACT FROM AUTHOR]

Effect of diets containing untreated or processed barley grain [treated with sugar beet pulp extract (SBPE) or double sulphate of aluminium and potassium (ALUM)] and different levels of rumen undegradable crude protein (RUP) on production, rumen fermentation and blood metabolites of lactating Holstein cows were investigated. Untreated soybean meal (SBM) or xylose protected 'Yasminomax soy® (YAS)' was included to represent a low (LR, 4.2% DM) and high (HR, 5.4% DM) RUP diets, respectively. Experimental diet was as follows: (a) untreated barley grains with high RUP (HRCON); (b) untreated barley grains with low RUP (LRCON); (c) ALUM‐treated barley grain with high RUP (HRAL; (d) ALUM‐treated barley grain with low RUP (LRAL); (e) SBPE‐treated barley grain with high RUP (HRSE); and (f) SBPE‐treated barley grain with low RUP (LRSE). The experiment was conducted as a completely randomized design with lactating dairy cows (n = 36) averaging 215 ± 18 days in milk, milk yield 31.7 ± 5.8 kg/day, 620 ± 61 kg body weight. Diets containing processed barley grain increased feed intake, while decreased both rumination and eating (p < 0.001). Feed intake of dairy cows on Low RUP and High RUP were 23 and 24 kg/day, respectively (p < 0.01). Daily production of milk fat, protein, lactose and total solids was improved when the processed barley grain was included in the diets (p < 0.05). Present study pinpointed that the inclusion of the processed barley grain in diets might improve production indices of dairy cows. [ABSTRACT FROM AUTHOR]

The immediate impact of prevailing environmental conditions on sensitivity of weeds to herbicides is well documented but little is known about the effects of parental environments on the responses of progeny to herbicides. It has been suggested that parental plants subjected to abiotic stress may result in progeny with increased tolerance to stresses. We tested this hypothesis by growing two populations of Palmer amaranth (Amaranthus palmeri) from California and Kansas under well‐watered (WW) and water‐deficit (25% of WW treatment) conditions to obtain F1 seeds. We then tested the responses of F1 seedlings to various doses of five herbicides with different modes of action. Dose‐response analysis of visual plant injury, aboveground biomass, and chlorophyll content showed that in 16 out of 30 comparisons, sensitivity to herbicides in A. palmeri progeny originated from a maternally water stressed environment was significantly lower than those obtained from WW plants. Only in one case the progeny from stressed plants was significantly more sensitive to herbicide (saflufenacil) than that from non‐stressed plants, and no differences were observed between the two types of progeny in all other (13) comparisons. The reduced sensitivity in progeny from stressed plants was consistent in terms of the evaluated response variables in population from California with the application of S‐metolachlor, rimsulfuron, and simazine; and in population from Kansas with the application of S‐metolachlor and rimsulfuron. Our study suggests that A. palmeri plants experiencing drought during the season may produce progeny that might be more difficult to control because of an increase in herbicide tolerance endowed through transgenerational effects of water stress. [ABSTRACT FROM AUTHOR]

Dose–response experiments are conducted to determine the toxicity of chemicals on organisms. The relationship between dose and response is described by different statistical models. The four‐parameter log‐logistic model is widely used in pesticide sciences to derive biologically relevant parameters such as ED50 and resistance index (RI). However, there are some common errors associated with the calculation of ED50 and RI that can lead to erroneous conclusions. Here we discuss five common errors and propose guidance to avoid them. We suggest (i) all response curves must be fitted simultaneously to allow for proper comparison of parameters across curves, (ii) in the case of nonparallel curves absolute ED50 must be used instead of relative ED50, (iii) standard errors or confidence intervals of the parameters must be reported, (iv) the e parameter in asymmetrical models is not equal to ED50 and hence absolute ED50 must be estimated, and (v) when the four‐parameter log‐logistic model returns a negative value for the lower asymptote, which is biologically meaningless in most cases, the model should be reduced to its three‐parameter version or other types of model should be applied. The mixed‐effects model and the meta‐analytic approach are suggested as appropriate to average the parameters across repeated dose–response experiments. © 2021 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Estuarine ecosystems are threatened by climate change and biological invasions. Among global changes, sea‐level rise is broadly impacting tidal wetlands, through increases in salinity and alteration of inundation regimes. Extant freshwater plant species are often presumed to be limited to reaches of estuaries with low salinity and narrow tidal ranges. However, the potential for invasive freshwater species (e.g., Iris pseudacorus) to persist and spread with increased salinity and flooding is poorly understood and can jeopardize native biodiversity and other wetland ecosystem services. The successful establishment of invasive plants will be dependent on their tolerance to salinity and inundation, starting with the germination life stage. Changes to abiotic estuarine gradients may alter the germination process of tidal wetland plant species that underlies significant patterns of plant community composition and biodiversity. We explored germination responses of seeds from two invasive I. pseudacorus populations from freshwater and brackish tidal sites in California's San Francisco Bay–Delta Estuary. We tested germination dynamics under salinity levels ranging from freshwater to seawater (0, 12.5, 25, and 45 dS/m) and two hydrological conditions (moist and flooded). Salinity levels >12.5 dS/m inhibited germination of seeds from both populations, consistent with viviparism and seedling emergence recorded at field sites. However, seeds exposed to seawater for 55 d germinated once exposed to freshwater. Germination velocity and seed buoyancy differed between populations, likely due to differences in seed coat thickness. Our results demonstrate that after 55 d in seawater, buoyant seeds of I. pseudacorus retain their ability to germinate, and germinate quickly with freshwater exposure. This suggests that invasive populations of I. pseudacorus can colonize new sites following potentially long‐distance dispersal of buoyant seeds with tidal currents. These findings inform risk assessments and highlight the need to prioritize the management of invasive I. pseudacorus in estuarine ecosystems impacted by rising sea level. [ABSTRACT FROM AUTHOR]

PREMISE: The importance of hybridization to invasion has been frequently discussed, with most studies focusing on the comparison of fitness‐related traits between F1 hybrids and their parents and the consequences of such fitness differences. However, relatively little attention has been given to late‐generation hybrids. Different fitness landscapes could emerge in later generations after hybrids cross with each other or backcross with their parents, which may play an important role in plant invasion and subsequent speciation. METHODS: In this study, artificial crosses were conducted to generate multiple generations, including F1, F2, and backcrosses between two invasive species: Cakile edentula (self‐compatible) and C. maritima (self‐incompatible). Putative hybrids were also collected in the sympatric zone and compared with their co‐occurring parents for phenotypic and genetic differences. RESULTS: Genetic data provided evidence of hybridization happening in the wild, and phenotypic comparisons showed that natural hybrids had intermediate traits between the two species but showed more similarity to C. maritima than to C. edentula. The asymmetry was further identified in artificial generations for several phenotypic characters. Furthermore, backcrosses exhibited different patterns of variation, with backcrosses to C. maritima having higher reproductive output than their counterparts. CONCLUSIONS: Our results suggest that hybridization and introgression (backcrossing) in Cakile species is asymmetric and most likely to favor the proliferation of C. maritima genes in the mixed population and thus help its establishment, a finding that could not be predicted by characterizing F1 hybrids. [ABSTRACT FROM AUTHOR]

Abstract: Bullock et al. (Journal of Ecology 105:6‐19, 2017) have suggested that the theory behind the Wald Analytical Long Distance (WALD) model for wind dispersal from a point source needs to be re‐examined. This is on the basis that an inverse Gaussian probability density function (pdf) does not provide the best fit to seed shadows around individual source plants known to be dispersed by wind. We present two reasons why we would not necessarily expect any of the standard mechanistically derived pdfs to fit real seed shadows any better than empirical functions. Firstly, the derivation of “off‐the‐shelf” pdfs such as the Gaussian, exponential and inverse Gaussian involves only one of the processes and factors that together generate a real seed shadow. It is implausible to expect that a single‐process model, no matter how sophisticated in detail, will capture the behaviour of an entire, complex system, which may involve a number of sequential random processes, or a superposition of parallel random processes, or both. Secondly, even if there is only one process involved and we have a perfect model for that process, the basic parameters of the model would be difficult to pin down precisely. Moreover, these parameters are unlikely to remain constant over a dispersal season, so that effectively we observe the outcome of a linear combination of dispersal events with different parameter values, constituting a form of averaging over the parameters of the distribution. Simple examples show that averaging a pdf over its parameters can lead to a pdf from an entirely different class. Synthesis. The failure of the inverse Gaussian model to fit seed shadow data is not in itself a reason to doubt the validity of the Wald Analytical Long Distance model for movement of particles through the air under specified environmental conditions. A greater awareness is needed of the differences between the Wald Analytical Long Distance and the inverse Gaussian (or Wald) and the purposes for which they are used. The complexity of dispersing populations of seeds means that any of the standard mechanistically derived pdfs will actually be merely empirical in this context. Shape and flexibility of a pdf is far more important for adequately describing data than some perceived higher status. [ABSTRACT FROM AUTHOR]

Aim To unravel the genetic processes involved in a case of invasion by one species, the self-incompatible Cakile maritima Scop. (Brassicaceae) in Australia, as it has replaced a related prior invader, Cakile edentula (Bigelow) Hook. Location Southern and eastern coastlines of Australia. Methods Genetic diversity within and between populations was characterized at a continental scale using microsatellite ( SSR) markers to examine nuclear diversity and cleaved amplified polymorphic sequence ( CAPS) markers to examine chloroplasts. DNA was sourced from 24 populations of C. maritima along its putative invasion trajectory and, for comparison, from four populations of C. edentula that are currently being invaded by C. maritima. Analysis of Molecular Variance and a Bayesian assignment method were used to explore the data. Results No evidence was found for progressive loss of diversity in C. maritima in the putative direction of range expansion. Western and south-eastern populations of C. maritima have almost certainly resulted from independent introductions, although there is evidence of very limited gene flow from west to east. There was considerably greater, spatially structured variation in the south-east, suggesting multiple introductions of C. maritima to that region. We found evidence of hybridization and introgression from C. edentula into C. maritima, both in the two regions where they are currently sympatric and elsewhere. Main conclusions The invasion history of a species spreading in a largely one-dimensional habitat can still be highly complex and difficult to interpret. Regional patterns of variation in C. maritima indicate several introductions from different parts of the native range, limited gene flow from the first introduction eastwards and genetic drift within Western Australia. There has also been bi-directional gene flow between this species and C. edentula. The significance of the introgression from C. edentula into C. maritima with respect to natural selection, however, remains to be determined. [ABSTRACT FROM AUTHOR]

Aim Correlative species distribution models ( SDMs) often involve some degree of projection into novel covariate space (i.e. extrapolation), because calibration data may not encompass the entire space of interest. Most methods for identifying extrapolation focus on the range of each model covariate individually. However, extrapolation can occur that is well within the range of univariate variation, but which exhibits novel combinations between covariates. Our objective was to develop a tool that can detect, distinguish and quantify these two types of novelties: novel univariate range and novel combinations of covariates. Location Global, Australia, South Africa. Methods We developed a new multivariate statistical tool, based on the Mahalanobis distance, which measures the similarity between the reference and projection domains by accounting for both the deviation from the mean and the correlation between variables. The method also provides an assessment tool for the detection of the most influential covariates leading to dissimilarity. As an example application, we modelled an Australian shrub ( Acacia cyclops) widely introduced to other countries and compared reference data, global distribution data and both types of model extrapolation against the projection globally and in South Africa. Results The new tool successfully detected and quantified the degree of dissimilarity for points that were either outside the univariate range or formed novel covariate combinations (correlations) but were still within the univariate range of covariates. For A. cyclops, more than half of the points (6617 of 10,785) from the global projection space that were found to lie within the univariate range of reference data exhibited distorted correlations. Not all the climate covariates used for modelling contributed to novelty equally over the geographical space of the model projection. Main conclusions Identifying non-analogous environments is a critical component of model interrogation. Our extrapolation detection ( Ex Det) tool can be used as a quantitative method for exploring novelty and interpreting the projections from correlative SDMs and is available for free download as stand-alone software from . [ABSTRACT FROM AUTHOR]

The experiment was conducted under a controlled environment to study the effects of different temperature regimes (15/10°C, 20/15°C, and 25/20°C day/night) and sowing depths (0, 2, 4, and 6 cm) on the seedling emergence and early growth (height gain) of wheat (cv. Marvdasht) and wild barley ( Hordeum spontaneum). The cumulative emergence and plant height gain over time were modeled with the use of a logistic function. For a particular temperature regime, the maximum percentage emergence (E max) of wheat was higher than that of wild barley across all sowing depths. The maximum and minimum E max values for both species occurred at 20/15°C and 25/20°C, respectively. The time taken to reach 50% of the E max (i.e. E50) increased with the sowing depth in both species under all temperature regimes. The E50 of wild barley was greater than that of wheat for all temperature regimes, with maximum differences observed at 20/15°C. The greatest maximum plant height (H max) was observed at the surface planting for both plants. The H max was reduced at temperatures either lower or higher than 20/15°C, with a more notable reduction in wild barley. At all temperature regimes, the time taken to reach 50% of the H max (i.e. H50) increased linearly with the sowing depth but, at higher temperatures, the accelerated growth rate reduced the H50. The wild barley seedling emergence and height gain rate, as expressed relative to those of wheat, revealed the highest superiority of wheat over wild barley at 25/20°C and the sowing depth of 4 cm. [ABSTRACT FROM AUTHOR]

Field experiments were conducted at five locations in the major wheat production regions of Iran to evaluate the efficacy of sulfosulfuron in controlling weed barley species (including Hordeum spontaneum, Hordeum murinum, Hordeum distichon, and Hordeum vulgare) in the 2004–2005 and 2005–2006 growing seasons. Sulfosulfuron was applied either postemergence (POST) or preplant-incorporated (PPI) at 0, 20.25, 30.75, 40.5, 51.0, 60.75 or 71.25 g ai ha−1 to plots arranged in a randomized complete block design with four replications. Sulfosulfuron at the recommended rate (20.25 g ai ha−1) failed to provide acceptable control of the weed barley species. However, the level of control increased with the application rate, particularly at rates >51.0 g ai ha−1. Generally, PPI-applied sulfosulfuron resulted in markedly greater control levels than those of a POST application and complete control of H. murinum and H. vulgare was achieved with PPI-applied sulfosulfuron at all rates >20.25 and 30.75 g ai ha−1, respectively. In most cases, the wheat yield increased with the application rate without any crop injury. The highest yield increase (186%) was obtained with a PPI application of 71.25 g ai ha−1. [ABSTRACT FROM AUTHOR]