Weed Seeds Research Articles

Insecticides may facilitate the escape of weeds from biological control

Background Preventative pesticide seed treatments (hereafter preventative pest management or PPM) are common corn and soybean treatments, and often include both fungicides and neonicotinoid insecticides. While PPM is intended to protect crops from soil-borne pathogens and early season insect pests, these seed treatments may have detrimental effects on biological control of weed seeds by insects. Methods Here, in two 3-year corn-soy rotations in Pennsylvania USA, we investigated a PPM approach to insect management compared to an integrated pest management approach (IPM) and a “no (insect) pest management” (NPM) control. This was crossed with a grass cover crop to see if this conservation practice can help recover the ecosystem services affected by chemical pest management practices. We hypothesized that PPM and IPM approaches would release weed seeds from biological control by insects but cover crops would increase biological control. We measured the effect of these treatments on the weed-seed bank, mid-season weed biomass, granivorous insect activity-density, and weed-seed predation. Results We found that, contrary to our hypothesis, planting a cover crop decreased carabid activity-density without consistent differences in weed-seed predation. Pest management and cover crop treatments also had inconsistent effects on the weed-seed bank and mid-season weed biomass, but insecticide use without a cover crop increased the biomass of likely glyphosate-resistant marestail (Erigeron canadensis L.) at the end of the trial. Our results suggest that reducing insecticide use may be important when combating herbicide-resistant weeds. We found planting cover crops and/or avoiding the use of insecticides may combat these problematic weeds.

Taphonomy and labour at the Indus Valley site of Harappa (3700–1300 BC)

The emergence of early cities required new agricultural practices and archaeobotanical crop-processing models have been used to investigate the social and economic organisation of urban ‘consumer’ and non-urban ‘producer’ sites. Archaeobotanical work on the Indus Valley has previously identified various interpretations of labour and subsistence practices. Here, the authors analyse a large archaeobotanical assemblage from Harappa, Pakistan (3700–1300 BC), questioning some of the assumptions of traditional crop-processing models. The ubiquity of small weed seeds, typically removed during the early stages of crop processing, is argued to result from dung burning. This additional taphonomic consideration adds nuance to the understanding of Harappa's labour organisation and food supply with implications for crop-processing models in other contexts.

PHYSIOLOGICAL AND SEED HEALTH TESTING OF RICE SEED (ORYZA SATIVA L.) GROWN IN THE DALOA AREA (COTE DIVOIRE)

A survey was realized during the period of June, 2021 to August, 2022 in Daloa, Cote dIvoire to understand the rice cultivation practices. Then rice seed samples were collected to perform their health and quality, Dry inspection and blotter tests. Eight varieties of rice were collected, of which Wita 9, BkeAmlre and C15 are mainly grown under both rainfed and irrigated lowland. The water content of the rice seed samples collected fluctuated between 9 and 10 % showing that the farmers have a good command of post-harvest activities. the inert matter up to 56% and weed seeds in a mixture up to 9.47 % were found in rice seed samples collected. Although, these seeds showed good germination capacity with an average rate of 90%, among the seedlings having emerged, some presented color anomalies of the stem, collar and cotyledons ranging from 3 to 46%. The rotten grains (1.25 - 11%) invaded by molds and hard grains that remained intact (0.65 - 4%) throughout the test were found. Ten seed-borne fungi were detected from these seed samples. Some of the identified fungi could be associated with seedling abnormalities and grain rots during the germination.

The potential of cold plasma technology for weed control in the pre-growth and post-growth phases

Abstract. Bukhori A, Guntoro D, Sudradjat, Sugiarto AT. 2024. The potential of cold plasma technology for weed control in the pre-growth and post-growth phases. Biodiversitas 25: 3628-3636. Efforts to reduce the use of herbicides can be made by using cold plasma technology. This technology produces heat energy through the emission of UV plasma light, generated by electrical energy. This research investigates the potential of various cold plasma treatments to inhibit germination, inhibit the growth of weed seeds in soil media, and suppress weed growth. The study was conducted at the Ecotoxicology Laboratory and Seed Propagation Laboratory, Institut Pertanian Bogor, Bogor, Indonesia, from March to September 2023. Three types of weeds used were Asystasia gangetica (L.) T.Anderson, Cyperus rotundus L., and Eleusine indica (L.) Gaertn. Three experiments were designed for this study. The first experiment tested cold plasma on weed seeds, the analysis was conducted using a single-factor completely randomized designed with varying doses of cold plasma and four replications. The second experiment tested cold plasma technology in soil media, the analysis was conducted using a single-factor completely randomized designed with various doses of cold plasma and seven replications. The third experiment tested cold plasma on the growth of each weed, the analysis was conducted using a single-factor randomized block design with various doses of cold plasma and four replications. The research shows that the application of cold plasma at a dose of 14 kV for 85 seconds can inhibit germination and weed growth in soil media of each type of weed A. gangetica, C. rotundus, and E. indica.

РАЗРАБОТКА ТЕХНОЛОГИЧЕСКОЙ СХЕМЫ И ОБОСНОВАНИЕ ПАРАМЕТРОВ ОЧИСТКИ СЕМЯН ЛЮЦЕРНЫ

Despite the high effectiveness of chemical preparations against weeds, this fight begins with the preparation of seed material on seed cleaning lines. An urgent problem in cleaning crop seeds is the isolation of dodder seeds in the preparation of alfalfa seeds. Alfalfa cleaning is a time-consuming process in itself, due to the complex structure of the combine heap. In this regard, it is important to develop a technological scheme for cleaning the alfalfa heap, which will allow you to effectively separate dodder seeds on a par with other impurities. When developing the technological scheme for alfalfa purification, the parameters of the initial heap and its components were determined. When determining the composition of the alfalfa heap, it was found that the alfalfa heap consists of 40-60% of organic impurities, 10% of puny seeds, and up to 10% of the heap consists of unthreshed beans, and the alfalfa seeds themselves in the initial heap are usually no more than 30% of the total weight, it was also determined that weed seeds make up less than 1% of the original weight, nevertheless, the heap contained 0.02% of dodder seeds. On laboratory screens with slotted notches and round holes, the dimensional characteristics of the components are determined. On the sail classifier, the distributions of the components according to the critical speed of vinow were established. The data obtained made it possible to develop a technological scheme for cleaning alfalfa seeds, which allows you to effectively remove dodder seeds with minimal losses. Using the same equipment in laboratory conditions, the proposed alfalfa cleaning scheme was tested, which showed that by combining aspiration and sieve cleaning, it is possible to achieve 99.45% purity of seeds, with losses of no more than 1%, dodder was not found in the final material.

Assessment of Common Ragweed (Ambrosia Artemisiifolia L.) Seed Predation in Crop Fields and Their Adjacent Semi-Natural Habitats in Hungary

Ambrosia artemisiifolia has turned into a noxious weed species in agricultural fields and landscapes in Europe. Durable control options are still needed to limit the abundance of this species. Weed seed consumption by naturally occurring seed predators is a key ecosystem service in agricultural areas. Seed predation levels of common ragweed were examined in wheat and maize fields and adjacent semi-natural habitats (SNHs). To evaluate the weed seeds’ exposure to invertebrate seed predators, 20 cards each were set on the soil surface inside the crop field and in SNHs with four replications. Twenty seeds of ragweed were attached to sandpaper. Seed removal was assessed every 24 h of exposure for 5 days in June and November 2019, October 2020, and June 2021. The seed consumption level was measured according to the number of removed seeds from the seed cards. High consumption rates of ragweed seeds were found in all sampling rounds in both seasons and habitats. The seed predation rates in 2019 were stronger within crop fields in summer than in autumn with a slight difference between SNHs and inside fields. Our results demonstrate the possibility of seed predation contributing to Integrated Plant Protection (IPM) of common ragweed in rural areas.

Grassland restoration on linear landscape elements – comparing the effects of topsoil removal and topsoil transfer

Artificial linear landscape elements, including roads, pipelines, and drainage channels, are main sources of global habitat fragmentation. Restoration of natural habitats on unused linear landscape elements can increase habitat quality and connectivity without interfering with agricultural or industrial development. Despite that topsoil removal and transfer are widely applied methods in restoration projects, up to our knowledge these were previously not compared in the same study system. To address this knowledge gap, we compared spontaneous vegetation recovery after the elimination of positive (embankments) and negative landscape scars (drainage channels) in lowland alkaline landscapes in South Hungary. The novelty of our study is that we compared the fine-scale and landscape-scale results of both methods. At the fine scale, we monitored the spontaneous vegetation development on the created open surfaces in the first, second and fourth year after restoration in 160 permanent plots per year. For characterizing the habitat changes on the landscape scale, we prepared habitat maps and assigned naturalness scores to each patch before and after the restoration activities. Both restoration methods resulted in a rapid vegetation recovery at the fine scale, progressing toward the reference state. In the topsoil removal treatment, a large part of the soil seed bank was removed; therefore, the colonization of the bare surface was a slower process. Seeds of halophytes, including the endemic and protected Suaeda pannonica, were probably present in the deeper soil layers, and these species became established in the restored surfaces, despite being absent in the surrounding vegetation. For restoring vegetation cover, topsoil transfer was a more rapid option; however, vegetation closure and competition by generalist species and weeds hampered the establishment of target species. The removal of the landscape scars by both methods made the sites accessible for grazing. At the landscape scale, the two methods had different effects: there was a slight increase in the habitat naturalness in the topsoil removal site, and a slight decrease in the topsoil transfer site because of weed encroachment. Spreading an upper layer of nutrient-poor soil with low amounts of weed seeds, direct propagule transfer, and targeted grazing regimes could enhance restoration success.

The Potential of Deleterious rhizobacteria to Control Primary Weed <i>Echinochloa </i>sp. on Rice

Deleterious rhizobacteria (DRB) is one of the rhizobacteria that can be used as a bioherbicide and can stimulate plant growth. The objectives that can be obtained from this study are to determine the potential of DRB on the growth of weeds Echinochloa crusgalli and Echinochloa colona on rice. Variables observed in this study were identification of secondary metabolites, measurement of weed sprouts, percentage effectiveness of bacterial isolates against weed seeds, normal sprouts, abnormal sprouts, fresh seeds that did not grow and dead seeds. The aim of this study is to explore biological agents that can be used to control the main weeds of rice crops. This candidate could be a recommendation for environmentally friendly controls. Exploration of the DRB group was obtained by collecting soil samples around the roots of rice crops. Then isolate it, identify as morphologically and physiologically, and test it in vitro studies. The results showed that DRB had the potential to control weed growth and could stimulate the growth of rice. The application of PFA and PFB isolates had a significant effect on inhibiting the length of weed roots and buds, the average percentage of control effectiveness > 80-90%. Novelty in this study could be found as candidate groups of DRB bacteria with specific locations to control the weed Echinochloa sp. on rice crops. For society, this research could be an alternative to reduce dependence on synthetic herbicides . DRB has the potential to be formulated into a bioherbicide to control weeds.

The effects of essential oils from two different Satureja hortensis L. genotypes harvested at different times on weed seed germination

The most important allelopathic effect of essential oils is that they prevent the germination of some plant seeds. In this study, essential oils were obtained from different form periods (beginning of flowering, mid-flowering and end of flowering) of 2 genotypes of S. hortensis plant. Subsequently, different doses of essential oils (0.5, 1, 2, 4, 8 and 16 µl petri-1) were used from weeds such as giant amaranth (Amaranthus palmeri L.), wild oats (Avena fatua L.), purslane (Portulaca oleracea L.), wild mustard (Sinapis arvensis L.) and cress (Lepidium sativum L.), durum wheat (Triticum durum L.) and pepper (Capsicum annuum L.) seeds from cultivated plants were investigated. According to the results of the study, germination was negatively affected due to the increase in the application doses of essential oils, and the highest effect was determined as 2 µl petri-1 in A. palmeri and oleracea seeds, 4 µl petri-1 in A. fatua seeds and 8 µl petri-1 in S. arvensis. For the effects of essential oil doses, the highest LD50 values for the seeds of A. palmeri, P. oleracea, A. fatua and S. arvensis were found to be 0.159, 0.189, 1.043 and 3.087, respectively, while the highest LD90 values were determined to be 0.547, 0.673, 2.895 and 8.398, respectively. As a result of the study, it was seen that essential oils have a significant bioherbicidal effect on weed seeds and it is thought that this method will make a significant contribution to the alternative control of weeds.

Effect of Forced Aeration and Turning Method on Manurial Value of Cattle, Goat and Poultry Manure Compost

Composting is the transformation of organic material through decomposition in to a biologically humus rich substance suitable for growing plants. The good management of those wastes would be an effective means of organic matter restoration through carbon restitution to the depleted soils through organic amendments. A properly managed composting process can destroy weed seeds, plant pathogens and human pathogens. The main goal of composting is carbon sequestration and enhances soil quality. Compost analysis assures buyers of bulk compost in addition to receiving good value for their money and safe organic fertilizer. Composting has four phases viz., mesophilic (21-45℃, thermophilic (45-68℃), mesophilic-II (<45℃) and maturation phase (Papale et al., 2021). The mesophilic phase also called hot phase, during which heterogeneous group of microorganisms were metabolically active and degrade the soluble compounds like sugars. The second phase is thermophilic phase/curing phase. Mesophilic organism was replaced by thermophilic organism and complex organic matter are degraded at this stage. High temperature in compost destroys the pathogenic organisms and contaminants. Composting is one of the methods used and among this forced aeration and turning method helps to improve the manurial value of compost. The present study is conducted to evaluate the effect of forced aeration and turning method in manurial value of cattle, goat and poultry manure compost.

Germination Biology of Three Cyperaceae Weeds and Their Response to Pre- and Post-Emergence Herbicides in Paddy Fields

(1) Background: Cyperaceae weeds have become a major type of weed in local paddy fields in China. (2) Methods: We assessed the impact of environmental factors, including temperature, light, salinity, water stress and soil depth, on the germination and emergence of three dominant Cyperaceae weeds: Cyperus difformis L., C. iria L. and Fimbristylis littoralis Gaudich. Using the dish dipping method, the performances of the pre- and post-emergence herbicides commonly used in paddy fields on three Cyperaceae weeds were evaluated using the pot method. (3) Results: The seeds optimally germinated at 35 °C in constant conditions and 25 °C/40 °C in alternating conditions. The seeds of the three Cyperaceae weeds were sensitive to light and could not germinate under dark conditions. The germination rate of the three weeds decreased with the increase in the NaCl concentration and water potential; the three weeds could not germinate at a 320 mmol·L−1 NaCl concentration and −0.1 MPa water potential. When the pH levels were 4 to 9, the germination rates of the three weeds were all greater than 80%. The burial depths to inhibit 50% of the emergence of C. difformis, C. iria and F. littoralis were 0.27, 1.06 and 0.42 cm, respectively. The control efficacy of the pre-emergence herbicides of pretilachlor, butachlor and oxyfluorfen on the three weeds were all above 90% at the recommended dose in the field. Halosulfuron-methyl, florpyrauxifen-benzyl and bentazone could effectively control the three Cyperaceae weeds; their performances on the three weeds at the 3- to 4-leaf stage were all above 82%. (4) Conclusions: The three Cyperaceae weed seeds have a strong adaptability to temperature, water potential, salinity and soil depth, and these weeds are sensitive to most pre- and post-emergence herbicides. Therefore, taking Cyperaceae weed seeds into the deep soil layer by tillage or selecting appropriate herbicides according to their growth stages can effectively control Cyperaceae weeds in rice fields.

Investigation of the Allelopathic Effects of Different Faba Bean (Vicia faba L.) Genotypes Against Various Weeds

Many allelopathic crops are cultivated in agricultural fields, and these plants can influence the growth of other plants in the cultivation environment with their phytotoxic compounds. One of these plants is the faba bean. In this study conducted under the ecological conditions of Sakarya/Arifiye, the allelopathic effects of Eresen-87, Salkim, Bilecik, and Sakarya faba bean genotypes on weeds such as Johnson grass (Sorghum halepense L.), curly dock (Rumex crispus L.), purslane (Portulaca oleracea L.), and wild mustard (Sinapis arvensis L.) were investigated. Weed seeds used in the experiment were collected from agricultural fields in the Sakarya province. Extracts from dried plant parts of faba bean genotypes were prepared and applied to petri dishes containing weed seeds at concentrations of 5% and 10%, with four replications. At the end of the research, it was observed that all faba bean genotypes at all application doses caused a decrease in germination rate (%), root length (cm), and shoot length (cm) parameters in the four weed species tested. The best results were determined as Eresen-87 and Bilecik at 10% concentration. When the activities of fresh and dry extracts of faba bean genotypes was compared, it was determined that dry application had a higher allelopathic effect.

Weed Seeds in Marketed Wheat and their Identification

Weed seeds of fifteen species representing 12 genera and 7 families have been observed, contaminated in wheat samples available in Calcutta ration shops. A key has been prepared for identification of these seeds.

Method of corn contamination decreasing after later harvesting predecessors under energy-storage soil maintenance system in irrigation landscapes

The research was carried out at Agrofirm Chokh of the Gunibsky district in the Kizilyurt transhumance zone of the Republic of Dagestan on light chestnut soil. The humus content in the arable layer is 2.77%, P2O5 – 2.21, K2O – 32.8 mg/100 g of soil, the density of the arable layer is 1.24 g/cm3, the lowest moisture capacity (MC) of the soil layer 0–0.6 m is 29.2%. We studied the influence of two corn predecessors: sunflower and corn itself during the main tillage for corn based on plowing to a depth of 28–30 cm without skimmers and with skimmers. During the autumn period, after harvesting the predecessors, the soil was not cultivated, and in the spring, upon the onset of its physical ripeness, two treatments were carried out in a layer of 0–15 cm with disk cultivators to crush the plant residues of the previous crop and plowing to 28–30 cm with a PLN-4-35 plow when physical ripeness of the soil in this layer. It has been established that a radical way to reduce the weediness of corn crops and increase its yield in the irrigated conditions of the Western Caspian region when placed after late-harvested predecessors, including repeated sowings in the same field, is to carry out basic tillage and moisture-recharging irrigation in the spring of the year of sowing. To chop the plant mass remaining after harvesting the predecessor, double processing with disc implements should be carried out before plowing. Plowing is carried out with skimmers, which ensure uniform distribution of weed seeds in the surface layer and their simultaneous germination at a later date than when plowing without skimmers. Subsequently, their life activity is limited to vegetative corn plants. The infestation of corn crops with such soil treatment is reduced three times, the corn yield for the predecessor corn increases by 1.12 t/ha of grain (16.3%), after sunflower – 1.32 t/ha (17.8%).

Allelopathic Effects of Corn Straw and Its Water Extracts on Four Weed Species and Foxtail Millet.

Straw covering is a protective tillage measure in agricultural production, but there is relatively little research on the allelopathic effects of corn straw on weeds and foxtail millet. This experiment studied the allelopathic effects of corn straw on four weeds (Chenopodium album, Setaria viridis, Echinochloa crus-galli and Amaranthus retroflexus) in foxtail millet fields, and also measured the growth indicators of foxtail millet. The study consisted of Petri dish and field experiments. Five treatments were used in the Petri dish experiment: clear water as control (0 g/L, TCK) and four types of corn straw water extracts. They were, respectively, the stock solution (100 g/L, T1), 10 X dilution (10 g/L, T2), 50 X dilution (2 g/L, T3), and 100 X dilution (1 g/L, T4) of corn straw water extracts. Additionally, seven treatments were set up in the field experiment, consisting of three corn straw covering treatments, with covering amounts of 3000 (Z1), 6000 (Z2) and 12,000 kg/ha (Z3), and four control treatments-one treatment with no corn straw cover (CK) and three treatments involving the use of a black film to create the same shading area as the corn straw covered area, with black film coverage areas of 50% (PZ1), 70% (PZ2), and 100% (PZ3), respectively. The results showed that the corn straw water extract reduced the germination rate of the seeds of the four weeds. The T1 treatment resulted in the allelopathic promotion of C. album growth but the inhibition of S. viridis, E. crus-galli, and A. retroflexus growth. Treatments T2, T3, and T4 all induced the allelopathic promotion of the growth of the four weeds. The order of the effects of the corn straw water extracts on the comprehensive allelopathy index of the four weed seeds was as follows: C. album > S. viridis > A. retroflexus > E. crus-galli. With an increase in the corn straw mulching amount, the density and total coverage of the four weeds showed a gradual downward trend, whereas the plant control effect and fresh weight control effect showed a gradual upward trend. All indices showed the best results under 12,000 kg/ha of mulching and returning to the field. Overall, corn straw coverage significantly impacted the net photosynthetic rate and transpiration rate of foxtail millet and increased the yield of foxtail millet. Under coverages of 6000 and 12,000 kg/ha, the growth of foxtail millet is better. Based on our findings, we recommend a corn straw coverage of 12,000 kg/ha for the allelopathic control of weeds in foxtail millet fields.

Influence of cultivation methods on the soil aggregate state in the context of weed development in winter wheat plantations

Weed control in winter wheat crops is an important issue. There is a risk of increasing populations of certain weed species that are resistant to some of herbicides used for winter wheat crops. This could be controlled by a combination of agronomic, mechanical, chemical, and biological methods. After introducing winter wheat into the rotation and improving tillage, the weediness of regular black soils with perennial root and emerged weeds were significantly reduced. The formation of nodal and rudimentary roots had a significant effect on the productivity of winter wheat under different soil moisture conditions. The highest yield of winter wheat was obtained when sown at the optimum time, with higher stem density and ear productivity due to better grain fullness. We studied what effects did the tillage methods have on the aggregate state of the soil in relation to weed development in winter wheat crops, finding that the structural and aggregate composition of the soil played an important role in winter wheat crops, influencing both the development of the crop root system and the water-physical balance of the chernozem, as well as naturally influencing the course of erosion processes in the experimental plots, and having a universal dynamic in terms of adaptation of aggregation and disaggregation processes. Prolonged mechanical stress on soil can cause destruction of its structure. For instance, continuous ploughing or moldboardless tillage with little or no manure application may permanently reduce soil fertility by increasing humus mineralisation. Subsequently, these factors may cause a significant decline in the soil's structural and aggregate composition, resulting in larger amounts of dusty particles smaller than 0.25 mm and cloddy particles larger than 10–12 mm. The soil's structural condition before sowing winter wheat in early September, on average for 2011–2016, indicates increased dispersion of the tilth layer (0–10 cm) in the experimental variants where shallow disc tillage of 10–12 cm was applied. Increase in the number of clods larger than 10 mm in the areas where moldboardless tillage had been applied can be attributed to significant soil drainage. The soil's aggregate state was rated as good, with 8.7% in the 0–10 cm soil layer and 1.7% of clods > 10 mm in the 0–30 cm layer. In 2014–2016, it was rated as satisfactory, with 7.4% and 9.8% of clods > 10 mm, respectively. Shallow disc cultivation resulted in slightly worse indicators: 6.6% and 8.3% of clods > 10 mm in soil layer 0–10 cm and 0–30 cm, respectively, in 2011–2013; and 7.2% and 6.9% of clods > 10 mm, respectively, in 2014–2016. In general, the parameters of optimal structural condition were positive. The tillage method used had a considerable effect on weed growth and development, particularly for those with a root and rhizome structure. It also affected the prevalence and development of pests and diseases in winter wheat. Agrotechnical methods of weed control do not guarantee complete destruction of weeds. Mechanical moldboardless tillage to the depth of 14–16 cm and disc tillage to the depth of 10–12 cm left the fields with 4.1 to 8.8 annual weeds per square meter and 1.3 to 3.3 specimens of harmful root weeds such as Convolvulus arvensis, Lactuca tatarica and Cirsium arvense. Mechanical moldboardless tillage to the depth of 14–16 cm and disc tillage to the depth of 10–12 cm left the fields with 4.1 to 8.8 annual weeds per square meter and 1.3 to 3.3 specimens of harmful root weeds such as Convolvulus arvensis, Lactuca tatarica and Cirsium arvense. Post-harvest residues (4–5 t/ha) can provide almost complete protection against weeds by covering the soil surface. However, pests and diseases may spread more easily due to preservation of fungal spores on the surface of plant residues and preservation of pest larvae in the straw and soil. The distribution of weed seeds in the soil was altered when the rotational tillage of common chernozems in winter wheat cultivation technology had been replaced with energy–saving minimum tillage (shallow flat-cutting disc tillage). This resulted in the concentration of most of the weed seeds (85–90%) in the upper soil layer (0–10 cm).

The effect of temperature and exposure time on redroot pigweed (Amaranthus retroflexus) and yellow foxtail (Setaria pumila) seed mortality in the natural soil seedbank

Abstract Heat disinfection of soil can be used to reduce the content of the soil seedbank. However, species differ in the lethal temperature needed for seed destruction and mortality. Laboratory research was conducted on the seeds of two weed species, redroot pigweed (Amaranthus retroflexus L.) and yellow foxtail [Setaria pumila (Poir.) Roem. & Schult]. The soil samples were collected at the experimental station Šašinovečki Lug, Zagreb, Croatia (45.850289°N, 16.180465°E), and exposed to linearly increasing constant temperatures of 40, 50, 60, 80, 100, and 120 C and exposure times of 30, 60, and 90 min in a laboratory oven. Weed seeds were then extracted from the soil using the sieve separation method and survival was measured by germinating seeds on filter paper. Germination counts were converted into percentages of mortality compared with untreated seeds. The results show that both temperature and exposure time significantly affected seed mortality of both weed species. Amaranthus retroflexus shows a greater susceptibility to high temperatures than S. pumila. A fitted three-parameter sigmoid model was used to define the relationship between temperature and exposure time needed for 50% (LT50) and 90% (LT90) seed mortality. The estimated LT50 values for A. retroflexus are 58.89 to 46.08 C over the 30- to 90-min exposure times; the estimated LT90 values were 113.36 to 65.72 C for the same durations. The estimated LT50 values for S. pumila over the 30- to 90-min exposure times ranged from 91.33 to 75.15 C; the estimated LT90 ranged from 98.79 to 90.32 C over the same durations. The research results contribute to the knowledge about the thermal sensitivity of seeds. Estimating efficacy of soil-heating treatments is essential when comparing the environmental, economic, and social costs of alternatives to conventional weed control methods.

IMPACT OF SOIL STERILIZATION FROM DIFFERENT LOCATIONS, WHEAT SEEDS CLEANING AND THEIR INTERACTIONS ON WEED CONTROL, AND YIELD AND YIELD COMPONENTS

IMPACT OF SOIL STERILIZATION FROM DIFFERENT LOCATIONS, WHEAT SEEDS CLEANING AND THEIR INTERACTIONS ON WEED CONTROL, AND YIELD AND YIELD COMPONENTS

Mechanisms of seed persistence in blackgrass (Alopecurus myosuroides Huds.)

AbstractSeed dormancy is the key factor determining weed emergence in agricultural fields and there is growing interest in weed seeds as a target for weed management. A foremost limitation to this approach is the lack of molecular insight into the mechanisms regulating dormancy in weed seeds. Alopecurus myosuroides (blackgrass) seeds were collected from a wheat field in the UK. At low temperatures, dormant (D) and after‐ripened (AR) seeds germinate similarly and at warm temperatures dormancy is enforced. RNAseq analysis at both temperatures for D and AR seeds demonstrated distinct mechanisms, involving abscisic acid and gibberellin signalling, are involved in after‐ripening and cold‐induced dormancy release. Exogenous application of selected plant growth regulators provided further insight into the phytohormone processes involved in seed dormancy in blackgrass. An untargeted analysis of the transcriptome revealed dormancy‐related processes beyond the regulation of germination, such as seed defence processes, which may have potential as targets for weed seedbank management. Our findings suggest that dormancy breaking can occur via multiple independent but connected hormone‐mediated mechanisms and provide a case study for the use of next‐generation sequencing to uncover the mechanisms involved in seed dormancy in weed and non‐model species.

Effect of Black Soldier Fly Larvae and Food Substrates on Weed Seed Emergence

Black soldier fly larvae (Hermetia illucens; BSFL) composting is biotechnology used for organic waste management and an alternative to traditional composting. We designed a two-phase experiment to evaluate the effect of BSFL composting on the emergence of the following six weed species: barnyardgrass (Echinochloa crus-galli), common ragweed (Ambrosia artemisiifolia), giant foxtail (Setaria faberi), ivyleaf morningglory (Ipomoea hederacea), redroot pigweed (Amaranthus retroflexus), and velvetleaf (Abutilon theophrasti). The first experiment phase was in the laboratory (laboratory composting phase), which consisted of 100 seeds of each weed species subjected to five composting treatments [two controls (nontreated and standard Gainesville diet alone) and three types of substrates (standard Gainesville diet, vegetable waste, food waste) + BSFL]. Live pupa weighed 179 mg with the standard Gainesville diet + BSFL and 205 mg with the food waste diet + BSFL. Dry pupa weighed 68 mg and 70 mg, respectively. The BSFL in the vegetable waste + BSFL treatment did not pupate. During the second experiment phase, the composting treatments were placed in a greenhouse to evaluate weed emergence. Emergence in the nontreated control was 62% for barnyardgrass, 38% for common ragweed, 26% for giant foxtail, 66% for ivyleaf morningglory, 3% for redroot pigweed, and 69% for velvetleaf. Compared with the nontreated control, all treatments with BSFL reduced the emergence of each weed species to ≤1%, except for velvetleaf. This study suggests that BSFL composting may effectively reduce weed seed emergence of many weed species and could be a safe alternative to conventional composting processes to minimize weed pressure in compost. However, efficacy may vary by weed species and may be dependent on seed characteristics, such as an impermeable seedcoat.