Velvetleaf Research Articles

Survival of Plants During Short-Term BOA-OH Exposure: ROS Related Gene Expression and Detoxification Reactions Are Accompanied With Fast Membrane Lipid Repair in Root Tips

For the characterization of BOA-OH insensitive plants, we studied the time-dependent effects of the benzoxazolinone-4/5/6/7-OH isomers on maize roots. Exposure of Zea mays seedlings to 0.5 mM BOA-OH elicits root zone-specific reactions by the formation of dark rings and spots in the zone of lateral roots, high catalase activity on root hairs, and no visible defense reaction at the root tip. We studied BOA-6-OH- short-term effects on membrane lipids and fatty acids in maize root tips in comparison to the benzoxazinone-free species Abutilon theophrasti Medik. Decreased contents of phosphatidylinositol in A. theophrasti and phosphatidylcholine in maize were found after 10–30 min. In the youngest tissue, α-linoleic acid (18:2), decreased considerably in both species and recovered within one hr. Disturbances in membrane phospholipid contents were balanced in both species within 30–60 min. Triacylglycerols (TAGs) were also affected, but levels of maize diacylglycerols (DAGs) were almost unchanged, suggesting a release of fatty acids for membrane lipid regeneration from TAGs while resulting DAGs are buildings blocks for phospholipid reconstitution, concomitant with BOA-6-OH glucosylation. Expression of superoxide dismutase (SOD2) and of ER-bound oleoyl desaturase (FAD2-2) genes were contemporaneously up regulated in contrast to the catalase CAT1, while CAT3 was arguably involved at a later stage of the detoxification process. Immuno-responses were not elicited in short-terms, since the expression of NPR1, POX12 were barely affected, PR4 after 6 h with BOA-4/7-OH and PR1 after 24 h with BOA-5/6-OH. The rapid membrane recovery, reactive oxygen species, and allelochemical detoxification may be characteristic for BOA-OH insensitive plants.

Architectural plasticity in response to population density in Abutilon theophrasti (Malvaceae)

AbstractAn increase in population density may result in the spatial and temporal heterogeneity of resources at scales smaller than an individual, inducing different modular responses at different positions of a plant, or architectural plasticity. To better understand how plants respond to density via architectural plasticity, we conducted a field experiment on an annual species, Abutilon theophrasti. Plants were subjected to three densities and harvested at 50 and 70 days, when each individual plant was separated into different layers vertically from bottom to top with an inter‐layer distance of 10 or 20 cm, before we measured a series of traits per layer and analyzed variations in them among layers, densities, and stages. Increased density reduced variation of traits among layers and had different effects on different layers of modular traits: it increased stem mass in the third to fifth layers (L3–L5) and increased stem diameter in the top layer, leading to an increase in stem density in lower layers and a decrease in stem density in the top layer. In addition, there was an increase in petiole length and mass, lamina size, and leaf number in upper layers, while they decreased in lower layers. Results suggested trade‐offs between upper and lower layers in stem density and leaf traits for plants in a dense population, which were important for keeping most leaves at higher positions to acquire light resources, while saving energy, in concert with the effort of extra stem elongation and the complex plasticity in branch traits.

Allelopathic effects of actinobacterial isolates on seed germination and early seedling growth of velvetleaf (Abutilon theophrasti Medik.)

This study aimed to examine in vitro allelopathic effects of actinobacterial isolates on seed germination and early seedling growth of velvetleaf (Abutilon theophrasti). Thirtyfive actinobacterial isolates were obtained from soil and compost in different phases of composting. Also, an experiment variant involving the herbicide mesotrione was set in the recommended amount of application, as a reference standard. The experimental results indicate statistically significant differences (p<0.05) between controls and all treatments with actinobacterial isolates regarding seed germination, and radical and shoot length. The highest inhibition (100%) was observed in seed germination and radical length in treatments with the isolates A10 and NOV2, compared to uninoculated starch casein broth (SCB) as control. Shoot length was shown to be the most sensitive parameter, where 100% inhibition was observed in the following treatments with actinobacteria: A010, A017, NOV2, NOV3, NOV4 and NOV5. Actinobacterial isolates showed a higher inhibitory effect on seed germination than treatment with the reference herbicide mesotrione.

Korovi u proizvodnji suncokreta u Hrvatskoj i njihovo suzbijanje

Sunflower is the most important oil crop in the Republic of Croatia. In the last two decades, it has been grown on average on 33,506 ha with a average grain yield of 2.66 t/ha. Weeds represent one of the most important causes of biotic stress, and their action is reflected in the competition for nutrients, water, light and space. The weed flora in sunflower crops in Croatia is extremely diverse, and we will most often meet: Polygonum persicaria L., Polygonum lapathifolium L., Ambrosia artemisiifolia L., Chenopodium polyspermum L., Amaranthus retroflexus L., Solanum nigrum L. emend Miller, Abutilon theophrasti Medik, Datura stramonium L., Xanthium strumarium L., Convolvulus arvensis L., Cirsium arvense (L.) Scop., Echinochloa crus-galli (L.) Pb., Setaria glauca (L.) Pb., Setaria viridis (L.) Pb., Digitaria sanguinalis (L.) Scop., Panicum spp. and Sorghum halepense (L.) Pers. For many years, weed control was based on the intensive use of chemical preparations, which were most often used after sowing and before emergence, in double or triple combinations. In addition to a number of advantages of using chemicals in sunflower production, the problem of broadleaf weeds was not satisfactorily solved until the advent of Clearfield, Clearfield plus and Express sun technology, i.e. hybrids tolerant to herbicides from the group of imidazolinone (imazamox) and sulfonyl-urea (tribenuron-methyl) at the beginning of this century. Integrated plant protection, including integrated weed management, with its holistic approach and greater application of direct and indirect non-chemical measures, is only environmental quality solution for controlling weeds in sunflowers.

三峡水库涪陵-奉节段消落带优势草本植物生态位与种间联结性研究

PDF HTML阅读 XML下载 导出引用 引用提醒 三峡水库涪陵-奉节段消落带优势草本植物生态位与种间联结性研究 DOI: 10.5846/stxb202011162953 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学青年基金面上项目（31270451）；三峡库区水环境演变与污染防治重点实验室开放基金项目（WETKL2012MS-07）；国家自然科学青年基金（41902024）；重庆市科委面上项目（cstc2019jcyj-msxmX0656） Niche and interspecific association of dominant herbaceous plants in the water-level-fluctuating zone of Fuling-Fengjie section of the Three Gorges Reservoir Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:参照相邻格子法对三峡水库中段（重庆市涪陵-奉节段消落带）地上植被进行调查，并运用生态位宽度、生态位重叠度、χ2检验等手段对优势草本植物生态位与种间联结性进行分析，能在一定程度上揭示三峡水库消落带优势草本植物的生态学特性、进而推测植被群落的演替趋势，以期为三峡水库消落带植被生态修复提供理论基础或参考建议。结果表明：（1）本次调查发现共有优势植物57种、隶属22科44属，其中狗牙根的生态位宽度最大、占绝对竞争优势。（2）在105个种对中，生态位相似比（Cih）≥0.50的种对有4个，生态位重叠值（Lih）≥0.50的种对有7个，种间相似性较小、竞争关系较弱。（3）χ2检验结果显示，优势植物种间正负联结比为1.33，正联结优势不明显；而Pearson与Spearman秩相关检验结果显示，种间正负联结比分别为0.54、0.75，负联结占优势。三种检验方式均表明，优势植物种间联结性较弱、稳定性相对较差、独立性相对较强。（4）种间联结系数（AC）≥0.60的种对数为7种，共同出现百分率（PC）≥0.7的种对数仅为1种。种间总体正联结性不强，物种趋于独立分布。（5）种间Pearson、Spearman秩相关检验与相应的Cih和Lih之间均呈显著正相关，表明种间正（负）关联越强、Cih和Lih越大（小）。（6）本文研究结果在一定程度上反映了三峡水库消落带植被退化生态系统现状，为最大程度提高消落带植物群落结构稳定性和物种多样性，针对小流域植被恢复与重建有如下参考建议：在整体上，可以采用以狗牙根（Cynodon dactylon（Linn.） Pers）、苍耳（Xanthium sibiricum）、鬼针草（Bidens pilosa L.）等为先锋植物，以狗尾草（Setaria viridis）、稗（Echinochloa crusgalli）、牛鞭草（Hemarthria altissima）等为伴生种的群落配置模式进行宏观布局；在局部上，可以采用稗（Echinochloa crusgalli）+苘麻（Abutilon theophrasti Medicus）、狗尾草（Setaria viridis）+黄花草木樨（Melilotus officinalis L.）、马唐（Digitaria sanguinalis）+水蓼（Polygonum hydropiper L.）等种对配置模式进行实地配置。 Abstract:This article refers to the adjacent grid method to investigate the aboveground vegetation in the middle section of the Three Gorges Reservoir (Fuling-Fengjie section of Chongqing City). We use niche width, niche overlap, χ2 test and other methods to compare the niche of dominant herbaceous plants, which could reveal the ecological characteristics of dominant herbaceous plants in the Three Gorges Reservoir water level fluctuating zone to a certain extent. Then, we infer the succession trend of plant community, so as to provide theoretical basis or reference suggestions for the ecological restoration of vegetation in the Three Gorges Reservoir water level fluctuating zone. The results showed that:(1) There were 57 plant species belonging to 22 families and 44 genera. The niche breadth of bermudagrass was the largest and occupied the absolute competitive advantage. (2) Among the 105 dominant plant species pairs studied, there were 4 species pairs with niche similarity ratio (Cih) ≥ 0.50 and 7 species pairs with niche overlap value (Lih) ≥ 0.50, indicating that the similarity between species was small and the competition was weak. (3) χ2 test results showed that the positive and negative association ratio of dominant plants was 1.33, indicating that the positive association advantage was not obvious. Pearson and Spearman rank correlation test showed that the positive and negative association ratio was 0.54 and 0.75, respectively, indicating that negative association was dominant. All the three tests showed that the interspecific association of dominant plants was weak, the stability was relatively poor and the independence was relatively strong. (4) The number of species with interspecific association coefficient (AC) ≥ 0.60 was 7 and the number of species with cooccurrence percentage (PC) ≥ 0.7 was only 1, indicating that the positive association between species was not strong and species tended to be independent. (5) Pearson and Spearman rank correlation tests showed a significantly positive correlation with Cih and Lih between species, indicating that the stronger the positive (negative) correlation, the greater the Cih and Lih. (6) In order to maximize the structural stability and species diversity of plant community in the Three Gorges Reservoir water-level-fluctuating zone, the following suggestions were put forward for vegetation restoration and reconstruction in small watershed:on the whole, a community configuration mode with Bermudagrass, Cocklebur, Bidens, etc. as the dominant plants, and Setaria, Barnyardgrass, and Virginia etc. as the companion species could be used for macro layout. In the local, the configuration mode of Echinochloa crusgalli+Abutilon bicolor, Setaria setifolia+Melilotus lutea, Digitaria tangutorum+Polygonum hydropiper etc. could be used for field configuration. 参考文献 相似文献 引证文献

Modeling of imazethapyr dose and velvetleaf (Abutilon theophrasti medik) density interaction on red bean (Phaseolus calcaratus L.) and velvetleaf competition

Background Redbean (Phaseolus calcaratus L.) is cultivated as an economic crop in the Mazandaran Province, Iran. Velvetleaf (Abutilon theophrasti Medik.) competes severely with red bean growth and reduces yield. Imazethapyr is a selective herbicide recommended for management of grasses and dicotyledonous weeds in different crops including beans. Objectives This research was conducted to develop an empirical model of red bean yield that incorporates the dose-responses of imazethapyr and velvetleaf densities. Methods Modeling of imazethapyr herbicide dose on red bean [...]

Chromosome numbers of invasive and potentially invasive species in the flora of the Republic of Altai. Post V

Chromosome numbers (2n) of 15 invasive and potentially invasive plant species from the families Asteraceae, Brassicaceae, Caryophyllaceae, Malvaceae, Onagraceae, Papaveraceae, Plantaginaceae, Poaceae, Polygonaceae, Portulacaceae, and Rosaceae are reported on the samples collected in the Republic of Altai. To determine the chromosome number (ploidy level), the method of direct counting was used. Among studied species, chromosome complements for Persicaria orientalis (2n = 22), Potentilla norvegica (2n = 42), Veronica persica (2n = 28) were first examined from Russia; for Papaver rhoeas (2n = 14) and Rumex obtusifolius (2n = 20) – from Asian part of Russia; for Bromus squarrosus (2n = 14), Cosmos bipinnatus (2n = 24), and Eriochloa villosa (2n = 54) – from Siberia. Abutilon theophrasti (2n = 42) and Lepidium densiflorum (2n = 32) were first studied from Western Siberia; Epilobium ciliatum subsp. adenocaulon (2n = 36), Portulaca oleracea (2n = 36), Spergularia rubra (2n = 36), and Xanthium strumarium (2n = 36) – from the Republic of Altai. Common distribution and the history of floristic findings of these species in the Republic of Altai are given. Previously published data on chromosome numbers from Russia are cited.

Comparative FT-IR Prospecting for Cellulose in Stems of Some Fiber Plants: Flax, Velvet Leaf, Hemp and Jute

Plant fibers are sustainable sources of materials for many industries, and can be obtained from a variety of plants. Cellulose is the main constituent of plant-based fibers, and its properties give the characteristics of the fibers obtained. Detailed characterization of cellulosic fibers is often performed after lengthy extraction procedures, while fast screening might bring the benefit of quick qualitative assessment of unprocessed stems. The aim of this research was to define some marker spectral regions that could serve for fast, preliminary qualitative characterization of unprocessed stems from some textile plants through a practical and minimally invasive method without lengthy extraction procedures. This could serve as a screening method for sorting raw materials by providing an accurate overall fingerprint of chemical composition. For this purpose, we conducted comparative Fourier Transform Infrared Spectroscopy (FT-IR) prospecting for quality markers in stems of flax (Linum usitatissimum L.), velvet leaf (Abutilon theophrasti Medik.), hemp (Cannabis sativa L.) and jute (Corchorus olitorius L.). Analysis confirmed the presence of major components in the stems of the studied plants. Fingerprint regions for cellulose signals were attributed to bands at 1420–1428 cm−1 assigned to the crystalline region and 896–898 cm−1 assigned to the amorphous region of cellulose. The optimization of characterization methods for raw materials is important and can find immediate practical applications.

Evaluation of Velvetleaf (Abutilon theophrasti) Maneh-Samalghan Ecotype Seed Response to Temperature and Light

Evaluation of Velvetleaf (Abutilon theophrasti) Maneh-Samalghan Ecotype Seed Response to Temperature and Light

Mycorrhizal Symbioses Enhance Competitive Weed Growth in Biochar and Nutrient-Amended Soils

Velvetleaf (Abutilon theophrasti) is a highly competitive weed in agroecosystems that is well-studied for its efficient nitrogen (N) acquisition, yet research on its phosphorus (P) uptake is lacking. One pathway may be through symbioses with arbuscular mycorrhizal fungi (AMF) which increase nutrient acquisition. These AMF benefits can be further enhanced by soil amendment with biochar, although effects may vary with different biochar production characteristics. We implemented a fully factorial nutrient and biochar addition experiment in a greenhouse for six months to determine how AMF nutrient uptake impacts plant growth and how these effects vary between two biochar types. We measured total above- and belowground biomass, plant tissue concentration (N and P), AMF colonization and activity rates, and soil media N and P availability. Overall, we observed few statistically significant results, however AMF N uptake may have been more beneficial to velvetleaf than AMF P uptake as evidenced by increased biomass and tissue N concentrations in treatments where N was only accessible by AMF. Additionally, by maintaining root to shoot ratios biochar may have provided plants with N and P (through sorption of nutrients to surfaces or its inherent properties) when nutrients were more difficult to access. We also found variable plant responses across the two biochar types used. Understanding how nutrient and biochar additions can influence weed competition is important for anticipating potential undesirable consequences of novel soil amendments such as biochar.

Stage-dependent plasticity in biomass allocation and allometry in response to population density in Abutilon theophrasti: a step forward to understanding the nature of phenotypic plasticity

How plants respond to density via modular plasticity is obscure, probably because relevant studies using covariance analysis (ANCOVA) and allometric analysis rarely focus on multiple stages of plant growth, and also the two approaches are seldom used simultaneously. In this study, a field experiment evaluated the effects of three density levels on resource allocation traits in Abutilon theophrasti and tested the degree to which these were explained by indirect effects of density on biomass over time. Results showed inconsistent responses in allocation traits and allometric relationships at each growth stage. At 30 days of plant growth, high density increased root/stem, root/leaf, and stem/leaf, but did not affect any allometric relationships. At 50 days, density altered most mass and ratio traits, but not for allometric exponents. At 70 days, density altered allometric relationships, but did not affect plant allocation patterns. The stage-dependent allometric relationships and the fact that allocation plasticity and allometric plasticity did not coincide both suggested that one-stage allometric plasticity might be apparent plasticity. In response to the increase of density, plants first altered the strategy of biomass partitioning and then growth rate or developmental stage, indicating that density effects intensified over time. For plasticity in a modular trait, size effects can be regarded as a component of (indirect) environmental effects, with the residual variation after removal of size effects being the other component of plant (direct) active response. The insights into apparent plasticity of allometry and two components of plasticity should be of essential importance to investigating phenotypic plasticity and its ecological and evolutionary implications.

Ensiling Reduces Seed Viability: Implications for Weed Management

Ensiling, a lactic acid fermentation process, is mainly used to preserve biomass. In addition, it has been shown to affect seed viability of some plant species. The extent to which this makes ensiling suitable as a weed control measure, however, has not yet been determined. Both the range of controllable species and the parameters of an ensiling process that safely kills seeds are still undefined. We aimed to determine the effect of varying substrate and ensiling conditions on the seed viability of 10 species selected to represent a wide range of different seed traits. Five different types of silages were made from maize or mixtures of wildflower and maize biomass and ensiled in lab-scale silos for 8 months. The pure maize silages were prepared under conditions either ideal or suboptimal for ensiling forage. Seeds of important weeds (Chenopodium album, Abutilon theophrasti) and of species from a wildflower mixture suitable for ensiling and biogas production (Cichorium intybus, Daucus carota, Echium vulgare, Malva alcea, Malva sylvestris, Melilotus albus, Melilotus officinalis) were tested. Seed viability was determined using a combination of tetrazolium and germination tests. Ensiling reduced seed viability across all 10 species significantly. Seed-killing efficacies of ensiling, however, differed widely among the species studied, largely related to whether the species could produce hard (physically dormant) seeds. Seeds from species without hardseededness were completely inactivated by ensiling, while the seed-killing efficacies for hardseeded species ranged from 5 to 60%. Variation in ensiled substrate and ensiling conditions had no consistent effect on seed survival. We concluded that ensiling has the potential to sustainably reduce seed viability of a wide range of species and therefore should be adopted as a component of integrated weed management in organic agriculture.

Morphological canalization, integration, and plasticity in response to population density in Abutilon theophrasti: Influences of soil conditions and growth stages.

Phenotypic integration and developmental canalization have been hypothesized to constrain the degree of phenotypic plasticity, but little evidence exists, probably due to the lack of studies on the relationships among the three processes, especially for plants under different environments. We conducted a field experiment by subjecting plants of Abutilon theophrasti to three densities, under infertile and fertile soil conditions, and analyzing correlations among canalization, integration, and plasticity in a variety of measured morphological traits after 50 and 70 days, to investigate the relationships among the three variables in response to density and how these responses vary with soil conditions and growth stages. Results showed trait canalization decreased and phenotypic integration and the degree of plasticity (absolute plasticity) in traits increased with density. Phenotypic integration often positively correlated with absolute plasticity, whereas correlations between trait canalization and plasticity were insignificant in most cases, with a few positive ones between canalization and absolute plasticity at low and medium densities. As plants grew, these correlations intensified in infertile soil and attenuated in fertile soil. Our findings suggested the complexity of the relationship between canalization and plasticity: Decreased canalization is more likely to facilitate active plastic responses under more favorable conditions, whereas increased level of integration should mainly be an outcome of plastic responses. Soil conditions and growth stage may affect responses of these correlations to density via modifying plant size, competition strength, and plastic responses in traits. We also predicted that decreased canalization can be advantageous or disadvantageous, and the lack of response to stress may demonstrate a stronger ability of adaptation than passive response, thus should be adaptive plasticity as active response.

Влияние замораживания семян Abutilon theophrasti Medik. и Eruca vesicaria (L.) Cav. на всхожесть, рост и развитие растений

A comparative study of the effect of different storage regimes of seeds (at + 5 ° С, -20 ° С and under deep freezing conditions at -196 ° С) of two cultivated plants of the Abutilon theophrasti Medik. and Eruca vesicaria (L.) Cav. on their viability and the development of plants from them in the field was carried out. Freezing increases the laboratory and field germination of the seeds of the A. theophrasti and does not significantly affect the germination of the seeds of the A. theophrasti, and also increases the germination energy of the seeds of both plant species. It did not cause the appearance of non-viable, ugly seedlings and plants. Plants went through a full development cycle and set full-value seeds. Biometric parameters of plants obtained from thawed seeds and control ones are very close. Cryopreservation is a promising way of storing seeds of the studied species, since it ensures longer periods of preservation of their viability. Keywords: ABUTILON THEOPHRASTI; ERUCA VESICARIA; SEED BANKS; LONG-TERM SEED STORAGE REGIMES; CRYOPRESERVATION

Crop residue and rainfall timing effect on pre-emergence herbicides efficacy using different spray nozzle types

Weed control success with pre-emergence (PRE) herbicides is affected by environmental factors including rainfall and plant residue. Two greenhouse experiments were conducted to evaluate PRE herbicide efficacy against johnsongrass [Sorghum halepense (L.) Pers.], prickly sida (Sida spinosa L.) and velvetleaf (Abutilon theophrasti Medik.). One experiment investigated herbicide efficacy under two crop residue amounts (2500 and 5000 kg ha−1) and the second examined herbicide efficacy influenced by simulated rain at two, four, and eight days after application (DAA). Five herbicides (pendimethalin, metribuzin, clomazone, imazethapyr and pyroxasulfone) and four nozzles types (XR, ULD, TTI and TTI60) were used. Nozzle type did not affect weed control across residue levels. Pendimethalin better controlled S. halepense under the low residue level. Imazethapyr efficacy for S. spinosa and A. theophrasti increased under high residue level. Imazethapyr applications for S. spinosa and A. theophrasti control were more effective when sprayed with the TTI nozzle regardless of rainfall timing. Longer periods without rain after application improved pendimethalin efficacy against S. spinosa and A. theophrasti, while pyroxasulfone better controlled S. spinosa with rain two DAA. Metribuzin and clomazone provided the best weed control among herbicides for all residue levels and rainfall scenarios.

Root morphological responses to population density vary with soil conditions and growth stages: The complexity of density effects.

AimHow plants cope with increases in population density via root plasticity is not well documented, although abiotic environments and plant ontogeny may have important roles in determining root response to density. To investigate how plant root plasticity in response to density varies with soil conditions and growth stages, we conducted a field experiment with an annual herbaceous species (Abutilon theophrasti).MethodsPlants were grown at low, medium, and high densities (13.4, 36.0, and 121.0 plants m−2, respectively), under fertile and infertile soil conditions, and a series of root traits were measured after 30, 50, and 70 days.ResultsRoot allocation increased, decreased, or canalized in response to density, depending on soil conditions and stages of plant growth, indicating the complex effects of population density, including both competitive and facilitative effects.Main conclusionsRoot allocation was promoted by neighbor roots at early stages and in abundant resource availability, due to low‐to‐moderate belowground interactions among smaller plants, leading to facilitation. As plants grew, competition intensified and infertile soil aggravated belowground competition, leading to decreased root allocation in response to density. Root growth may be more likely restricted horizontally rather than vertically by the presence of neighbor, suggesting a spatial orientation effect in their responses to density. We emphasized the importance of considering effects of abiotic conditions and plant growth stages in elucidating the complexity of density effects on root traits.

Effect of Clay, Soil Organic Matter, and Soil pH on Initial and Residual Weed Control with Flumioxazin

Greenhouse studies were conducted to evaluate the effects of soil organic matter content and soil pH on initial and residual weed control with flumioxazin by planting selected weed species in various lab-made and field soils. Initial control was determined by planting weed seeds into various lab-made and field soils treated with flumioxazin (71 g ha−1). Seeds of Echinochloa crus-galli (barnyard grass), Setaria faberi (giant foxtail), Amaranthus retroflexus (redroot pigweed), and Abutilon theophrasti (velvetleaf) were incorporated into the top 1.3 cm of each soil at a density of 100 seeds per pot, respectively. Emerged plants were counted and removed in both treated and non-treated pots two weeks after planting and each following week for six weeks. Flumioxazin control was evaluated by calculating percent emergence of weeds in treated soils compared to the emergence of weeds in non-treated soils. Clay content was not found to affect initial flumioxazin control of any tested weed species. Control of A. theophrasti, E. crus-galli, and S. faberi was reduced as soil organic matter content increased. The control of A. retroflexus was not affected by organic matter. Soil pH below 6 reduced flumioxazin control of A. theophrasti, and S. faberi but did not affect the control of A. retroflexus and E. crus-galli. Flumioxazin residual control was determined by planting selected weed species in various lab-made and field soils 0, 2, 4, 6, and 8 weeks after treatment. Eight weeks after treatment, flumioxazin gave 0% control of A. theophrasti and S. faberi in all soils tested. Control of A. retroflexus and Chenopodium album (common lambsquarters) was 100% for the duration of the experiment, except when soil organic matter content was greater than 3% or the soil pH 7. Eight weeks after treatment, 0% control was only observed for common A. retroflexus and C. album in organic soil (soil organic matter > 80%) or when soil pH was above 7. Control of A. theophrasti and S. faberi decreased as soil organic matter content and soil pH increased. Similar results were observed when comparing lab-made soils to field soils; however, differences in control were observed between lab-made organic matter soils and field organic matter soils. Results indicate that flumioxazin can provide control ranging from 75–100% for two to six weeks on common weed species.

Biodiesel preparation from Semen Abutili (Abutilon theophrasti Medic.) seed oil using low-cost liquid lipase Eversa® transform 2.0 as a catalyst

To decrease the cost of biodiesel production, undeveloped nonedible Semen Abutili seed oil (SASO) was first used as a feedstock to prepare biodiesel. Some low-cost liquid lipases were screened and used as green catalysts for biodiesel production via the ethanolysis of SASO. The effect of reaction factors on ethanolysis was optimized by the response surface methodology (RSM). The results demonstrated that SASO was a promising alternative feedstock, and Eversa® Transform 2.0 showed the best performance for biodiesel production from low-quality SASO feedstock (high FFA and phospholipid contents). In addition, Eversa® Transform 2.0 can be reused 3 times without significant loss. The influence of reaction factors on biodiesel yield decreased in the order of reaction temperature > lipase load > reaction time. The maximum biodiesel yield was 94.2 ± 1.3 % under the optimal conditions (lipase load 6%, water content 20 %, 7:1 (mol/mol) ethanol to SASO, 11 h, 37 °C). The kinetic parameters (Vmax and K'm) of the transesterification of SASO were 4.16 × 10−2mol/(L∙min) and 5.27 × 10-1 mol/L, respectively. The Arrhenius equation and activation energy, Ea, of Eversa® Transform 2.0-catalyzed transesterification of SASO were lnV0 = 4.8252–2382.3/T and 19.80 kJ/mol, respectively. The biodiesel produced from SASO was accordance with the ASTM D6751 standard, except for the oxidation stability. Thus, SASO, an undeveloped nonedible low-quality vegetable oil, can be used as a potential feedstock for biodiesel production, and the low-cost liquid lipase Eversa® Transform 2.0 can be used for biodiesel production.

An Instance Segmentation-Based Method to Obtain the Leaf Age and Plant Centre of Weeds in Complex Field Environments.

Leaf age and plant centre are important phenotypic information of weeds, and accurate identification of them plays an important role in understanding the morphological structure of weeds, guiding precise targeted spraying and reducing the use of herbicides. In this work, a weed segmentation method based on BlendMask is proposed to obtain the phenotypic information of weeds under complex field conditions. This study collected images from different angles (front, side, and top views) of three kinds of weeds (Solanum nigrum, barnyard grass (Echinochloa crus-galli), and Abutilon theophrasti Medicus) in a maize field. Two datasets (with and without data enhancement) and two backbone networks (ResNet50 and ResNet101) were replaced to improve model performance. Finally, seven evaluation indicators are used to evaluate the segmentation results of the model under different angles. The results indicated that data enhancement and ResNet101 as the backbone network could enhance the model performance. The F1 value of the plant centre is 0.9330, and the recognition accuracy of leaf age can reach 0.957. The mIOU value of the top view is 0.642. Therefore, deep learning methods can effectively identify weed leaf age and plant centre, which is of great significance for variable spraying.

Improving weed control in sustainable agro-ecosystems: Role of cultivar and termination timing of rye cover crop

Alternative strategies to control weeds are required at the field level to reduce herbicides and derived pollution. As cover crop, rye (Secale cereale L.) is adopted mainly because of its allelopathic weed control, which takes place through a strong inhibition of germination and seedling growth in several types of grass and broad-leaved weeds. The present study consisted of: i) a field trial, focused on the evaluation of biomass production and allelochemical concentration in the biomass, and in situ weed control at 30 days after termination (with two termination timings: T1 - heading phase and T2 - 10 days later) of 8 rye varieties; ii) a pot experiment, focused on the inhibition effect of mulches derived by those 8 rye varieties on four summer weeds: velvetleaf (Abutilon theophrasti Med.), lambsquarters (Chenopodium album L.), redroot pigweed (Amaranthus retroflexus L.), and common purslane (Portulaca oleracea L). Results showed that biomass production was the highest with Protector, closely followed by Primizia, Sito 70, Hellvus, Forestal, and Hymonta. In any case, rye mulching always reduced the weed biomass, especially with Fasto and Forestal. The allelochemical concentration in the biomass was the highest with Fasto and Forestal and decreased on average from T1 to T2 (–38% for total benzoxazinoids and –57% for isovitexin). Conversely, the rye biomass production increased (on average +77%), passing from T1 to T2. We also found that the reduction of weed biomass, compared with the control, is highly correlated with the allelochemical content in rye biomass in the case of T1 termination, while with the biomass production in the case of T2. In pots, a strong inhibitory effect on seedling growth due to rye mulching was observed for C. album (–76%), A. retroflexus (–56%), and P. olearcea (–84%), while not for A. theophrasti. We concluded that, regardless of the variety, adopting rye as a cover crop may be considered as a suitable practice to reduce weed pressure at the field level. Among all the varieties tested, Forestal and Protector showed the most significant weed suppression potential, due to the high amount of allelochemicals production for Forestal and high biomass production for Protector. Highlights - One month after rye termination, the weed biomass under mulching is reduced by 4 times, compared with the control. - When rye is terminated early, the allelochemical content in rye tissues reduces the weed biomass production. - When rye is terminated late, the weed biomass production is reduced by the amount of rye biomass. - Lambsquarters, redroot pigweed and purslane growth is inhibited by rye mulching, while velvetleaf is not affected.