Germination Of Weeds Research Articles

EVALUATING THE PHYTOTOXIC EFFECTS OF SOME PLANT SPECIES OF SEMI-ARID REGIONS

The most effective method for weed control is the use of herbicides. However, the scope of this method is narrowing down due to herbicide-resistant weeds and the non-availability of new chemistry herbicides. Hence, to explore natural weed management options, the herbicidal potential of three weed species extracts namely Opuntia ficus-indica, Murraya koenigii and Dryopteris felix-mas were evaluated in lab and wirehouse experiments. A completely randomized design with factorial arrangements was used for lab and completely randomized design was used for wirehouse experiments. Each experiment was repeated twice with four replications each time. Data pertaining to seed germination, seedling growth and physiological traits of crops and weeds were recorded using standard procedures. Data indicated that aqueous extracts of tested species depicted more phytotoxicity than N-hexane extracts against germination and seedling growth of lettuce in the lab experiment. Aqueous extract of Opuntia ficus-indica completely inhibited lettuce seed germination whereas, N-hexane extract of the same species has least effect on germination and germination traits like mean germination time, time taken to 50% germination, germination index. The aqueous extract of O. ficus-indica resulted in minimum lentil, mashbean, mungbean, parthenium and Trianthema portuclacastrum seedling leaf area, chlorophyll content, shoot, root length, dry weight and maximum electrolyte leakage. The foliar application of O. ficus-indica, M. koenigii and D. felix-mas water extracts on seedlings of lentil, mashbean, mungbean, parthenium and T. portuclacastrum followed the phyto-toxicity order O. ficus-indica aqueous extract ˃ D. felix-mas aqueous extract ˃ M. koenigii aqueous extract. The growth-inhibitory demonstrations of O. ficus-indica extract suggest that active substances with herbicidal properties are present in this plant which could be exploited as natural weedicide.

Phytotoxic Effects of Selected Herbal Extracts on the Germination, Growth and Metabolism of Mustard and Oilseed Rape

The use of plants that have high allelopathic potential as natural herbicides in the form of aqueous extracts is gaining popularity in environmentally friendly agriculture. Usually, their effect on the germination and growth of weeds is investigated. However, less attention is paid to the effect of the allelopathic compounds from extracts on cultivated plants. Therefore, the aim of this study was to evaluate the impact of herbal extracts that have allelopathic properties on selected physiological and biochemical processes of two plants of great economic importance—white mustard (Sinapis alba L.) and oilseed rape (Brassica napus L. var. oleifera). The extracts were prepared from mountain arnica (Arnica montana L.), ribwort (Plantago lanceolata L.), hypericum (Hypericum perforatum L.), common milfoil (Achillea millefolium L.), sunflower (Helianthus annuus L.) and sage (Salvia officinalis L.). The germination of white mustard and oilseed rape was most inhibited by the extracts that were prepared from sage and sunflower. Additionally, in the germinating plants, the sunflower extracts increased the membrane permeability, which indicates membrane injuries. The metabolic changes in the plants were monitored using isothermal calorimetry and FT-Raman spectroscopy. The total heat production, which provided information about the metabolic activity of the white mustard and oilseed rape, was decreased the most by the sage extract but generally all of the tested extracts disturbed the shape of the heat emission curves compared to the water control. The impact of the allelopathic compounds that are present in the herbal extracts on the metabolism of the seedlings was clearly visible on the FT-Raman spectra—in the fatty acids and flavonoids range, confirmed using a cluster analysis. In conclusion, the herbal extracts from medicinal plants that have herbicidal activity could be used as a natural herbicide for weed control, but since they may also have negative impacts on cultivated plants, preliminary tests are advisable to find the extract from the species that has the least negative effect on a protected crop.

Effect of Substrate Stratification on Growth of Common Nursery Weed Species and Container-grown Ornamental Species

Substrate stratification is a method of filling nursery containers with “layers” of different substrates, or different textures of the same substrate. Recently, it has been proposed as a means to improve drainage, substrate moisture dynamics, and optimize nutrient use efficiency. Substrates layered with larger particle bark as the top portion and smaller particle bark as the bottom portion of the container profile would theoretically result in a substrate that dries quickly on the surface, thereby reducing weed germination, but that would also retain adequate moisture for crop growth. The objective of this study was to evaluate the effect of stratified substrates on the growth of common nursery weeds and ornamental crops. This study evaluated the use of coarser bark (<0.5 or 0.75 inches) as the top substrate and finer bark (<0.38 inches) as the bottom substrate with the goal of reducing the water-holding capacity in the top 2 to 3 inches of the substrate to reduce weed germination and growth. Results showed that substrate stratification with more coarse bark on the top decreased the growth of bittercress (Cardamine flexuosa) by 80% to 97%, whereas liverwort (Marchantia polymorpha) coverage was reduced by 95% to 99%. Substrate stratification initially reduced the growth of ligustrum (Ligustrum japonicum) and blue plumbago (Plumbago auriculata), but there was no difference in the shoot or root dry weights of either species in comparison with those of nonstratified industry standard substrates at the end of 24 weeks. The data suggest substrate stratification could be used as an effective weed management strategy for container nursery production.

Can hemp hurd or paper mulch and biochar application improve weed management in matted-row strawberry production systems?

AbstractDuring 2015 and 2016, studies were conducted at Absaraka and Dickinson, North Dakota to evaluate the impacts of hemp (applied at 1156 m3 ha−1) and commercial paper mulch, as well as soil-applied biochar (applied at 11.25 m3 ha−1), on weed suppression and strawberry growth during the establishment year, and on weed suppression and strawberry yield during the production year, in a matted row production (MRP) system. During 2015, biochar influenced dry weed biomass only within the hemp mulch, with slightly more weed biomass associated with biochar application compared to zero biochar (3.1 vs 0.4 g m−2), suggesting that biochar may have increased weed germination and/or emergence from beneath hemp mulch. Biochar application also slightly increased soil pH, from 6.9 in non-amended soil to 7.0 in amended soil. Strawberry runner number during 2015 was greater in association with hemp or paper mulch compared to zero mulch (4.5 and 4.9 vs 2.4 runners plant −1, respectively). This result mirrored a similar differential in per berry mass across sites (7.6 and 7.4 vs 6.2 g berry −1 for hemp mulch, paper mulch and zero mulch, respectively). These results may be related to hemp and paper mulch reducing maximum soil temperatures during summer 2015. During the establishment year, both hemp and paper mulch suppressed weeds well compared to zero mulch, although at Absaraka hemp mulch provided slightly better weed suppression than paper mulch. During the production year, both mulches continued to suppress weeds compared to zero mulch at Dickinson. However, at Absaraka, only hemp mulch provided weed suppression compared to zero mulch, possibly because of faster paper degradation caused by greater numbers of large precipitation events and greater relative humidity at Absaraka compared to Dickinson. Weeds were removed from plots during 2015 to allow separation of weed suppression from other possible mulch impacts; therefore, yield data do not reveal striking differences among mulch treatments. Because previous research has demonstrated the impact of weed management during the establishment of strawberries in a matted row system, we concluded that hemp mulch may provide more durable weed suppression compared to paper mulch, which would increase strawberry yield protection in an MRP system. Material cost may be an issue for implementing hemp mulch, as hemp hurd cost was 25 times paper mulch at the application rates used in this study. However, hemp mulch could still be a beneficial option, especially for organic strawberry growers desiring a renewable and environmentally sound replacement for plastic mulch who are able to find affordable local sources of this material.

The influence of the method of manure removal and storage on the quality of organic products

The aim of this article was to compare the quality of manure in different ways of its removal and storage for environmental pollution. The research was conducted in three farms of Kyiv region with different methods of manure removal, storage and processing: using deep long-lasting straw litter (manure removal three times a year); with manure processing in a closed bioreactor-fermenter of the closed type; with manure settling in open lagoons. In all farms, the average annual livestock is 400 dairy cows. Samples for analysis of manure (processing waste) were taken the day before export to the field. The average daily air temperature during sampling was +21.3 °C. In terms of the sum of nitrogen, phosphorus and potassium content in 1 kg of fertilizers, the highest indicators were observed for the variant of keeping in deep litter – 7.69 g. intermediate bioreactors-fermenters observed intermediate values – 6.69 g. The highest moisture content of manure was during storage in the lagoon – by 19.71 % and 1.38 % more compared to the option on deep litter and in the bioreactor-fermenter. The lowest number of weed seeds was for storage in deep litter – 84 pcs/ml, which is 19 and 23 pcs/ml more than for processing in a bioreactor-fermenter and storage in the lagoon. The indicator of weed germination, which is very important from the point of view of future use of manure as an organic fertilizer in general, had positive indicators for all storage (processing) options. The germination rate of weeds for storage in deep litter was 5.72 %, which is 3.14 and 4.42 % less than for processing in a bioreactor-fermenter and in the lagoon. The largest emissions of N2O (nitric oxide) were in the variant of manure storage in the lagoon – 40712.45 kg, which is 39781.88 kg more than in the options of storage in deep litter and in the bioreactor-fermenter. The content of nitrogen, phosphorus, potassium and organic matter of fertilizer obtained from 1 kg of manure from deep litter, exceeded similar indicators of other methods of storage due to daily application of straw.

The influence of rainfall and tillage on wheat yield parameters and weed population in monoculture versus rotation systems

Extreme climate events (ECEs) of drought are becoming common in Mediterranean areas and farmers need adapt agricultural practices to achieve sustainability. This field study took place in to gain insight into the effects of seasonal rainfall, tillage and crop systems on wheat yield and weed parameters. Conventional (CT), minimum (MT) and no-tillage (NT) systems in wheat monoculture and rotation cropping systems were tested during 3 years of study (2014–2015, 2015–2016 and 2016–2017). Growing Season Rainfall (GSR) was the most influential factor on yield parameters and weed population. In 2016–2017, categorized as an extreme climate event by drought, the GSR accounted for 43.4% of the historical average. This year, the wheat yield (373 kg ha−1) and harvest index (0.18) were the lowest. In 2015–2016, scarcer autumn rainfall (44 mm) affected the weed germination period, reducing the density (17 plants m−2) and diversity of weed species (3 species m−2) while yield was favoured by high winter and spring rainfall (247 mm). Our study revealed that tillage effects was not significant on wheat yield, but NT systems consistently showed higher weed density and diversity than CT and MT despite the irregular GSR during this study. The rotation system presented higher values of wheat grain yield (781 kg/ha) and dry straw biomass (1803 kg/ha) but also weed biomass (48.54 g m−2) compared to monoculture (27.50 g m−2). NT and rotation combined increased the weed community although did not reduce the wheat yield compare to conventional systems even with an ECE of drought.

Bioherbicidal Actions of Common Purslane on Seed Germination and Growth of Some Crop and Weed Species

This study was conducted to examine allelopathic actions of Common Purslane Portulaca oleracea L. aqueous shoot and root extracts on germination of seeds and some growth parameters of wheat (Triticum aestivum) and rapeseed (Brassica napus). The experiment was performed in sterilized Petri dishes for one week at 22 °C. The experiment was arranged for completely randomized design. The concentrations were chosen for this study as (0%, 3%, 6% and 9%). The results indicated that the higher concentrations (6% and 9%) of both shoot and root extracts of common purslane caused significant reduction in seed germination whereas the lowest concentration caused the least negative impact on seed germination. Other growth polarimeters such as shoot and root length and shoot and root oven dry weight were significantly inhibited by the application of both Common Purslane aqueous shoot and root extracts at concentrations (6% and 9%) in wheat T. aestivum and rapeseed B. napus. However, dicot B. napus turned out to be more effected than monocot T. aestivum. The findings of this study suggest that common purslane aqueous shoot and root extracts can be recommended to utilize as bio-herbicide to supress seed germination and growth of weeds.

Biocidal Activity of Origanum vulgare subsp. hirtum Essential Oil

Toxic effect of Origanum vulgare subsp. hirtum (Link) Ietsw. essential oil was assayed on weeds (Lolium perenne L. Trifolium pratense L. and Trifolium repens L.), potato plants (Solanum tuberosum L.) and Myzus persicae Sulz. The GC-MS analysis of the essential oil revealed carvacrol as the main component. The essential oil solutions completely inhibited the seed germination of the target weeds at concentration 2 μL/mL in Petri dishes. In contrast, in soil, this effect was achieved at a concentration of 5 µL/mL for studied dicot and at 10 µL/mL for the monocot species. Total destruction of target weeds at post-emergence stage after spraying with solution of the essential oil in concentrate 10 µL/ mL was found. Mature potato plants were poorly affected by the essential oil. A completely toxic effect on M. persicae was established by applying a solution with a concentration of 3 μL/mL of the essential oil. The experimental data indicate that the essential oil of the species has great potential, as an alternative to synthetic biocides, for the production of eco-friendly formulations for pest control.

Rice–weed competition in response to nitrogen form under high and low transpirational demand

AbstractImplementation of water‐saving irrigation practices in lowland rice results in increased availability of nitrate (NO3−) in the soil and favours germination of upland weeds. Since plant species show a specific preference for either ammonium (NH4+) or NO3− as nitrogen (N) source, changes in both soil NO3− concentration and weed flora may affect the competition between rice and weeds. Further, the transpirational demand of the atmosphere might affect growth and competitiveness of lowland (wetland) and upland (dryland) weeds differently due to their adaptation to different ecological environments. Therefore, the study aimed to evaluate the effects of N source on growth, N uptake and competition between rice and common upland and lowland weeds under high and low vapour pressure deficit (VPD). Two rice (Oryza sativa) varieties (NU838 and KD18) differing in growth characteristics and two weed species (Echinochloa crus‐galli and Solanum nigrum) differing in their natural habitat were selected and grown hydroponically as monoculture or mixed culture at low or high VPD. N was supplied as 75%/25% or 25%/75% NH4+/NO3−. N uptake rates were measured in the first week, whereas dry matter (DM), N concentration in the plant, total N uptake and the activities of nitrate reductase and glutamine synthetase in the fresh leaves were determined two weeks after the onset of treatments. Independent of N source, both rice varieties and E. crus‐galli took up a larger share of NH4+, whereas S. nigrum took up a larger share of NO3−. N uptake of rice and E. crus‐galli was hardly affected by N source, whereas high NO3− led to significantly higher N uptake rates and total N uptake of S. nigrum. NU838 showed a higher competitiveness against weeds than KD18. In competition, high NO3− decreased the competitiveness of E. crus‐galli against NU838 but increased the competitiveness of S. nigrum against NU838. High VPD did not affect DM but increased N uptake of S. nigrum, leading to increased competitiveness of the weed at high transpirational demand. Competitiveness for N uptake appears to be an important trait as the relative N concentration in mixed plant communities was correlated with the activity of N‐assimilating enzymes and leaf growth, with a stronger response in rice than in weeds. Our results support the hypothesis that increased availability of NO3− in aerobic rice soils may be advantageous for the competitiveness of upland weeds, especially at high VPD, whereas it may be disadvantageous for common lowland weeds.

Predictive phytotoxic value of water-soluble allelochemicals in plant extracts for choosing a cover crop or mulch for specific weed control

Cover crops and mulches have become an alternative for soil management in vineyards due to the agronomic, environmental, and economic advantages, especially the possibility of weed control. Implicitly to this objective lies the idea of assessing the potential herbicide effect of the allelochemicals released by different cover crops and mulch species. With this objective, the present work evaluated the phytotoxic effects of 12 aqueous extracts of selected species with potential use as a cover crop or mulch: a Bromus species mixture (B. hordeaceus L. and B. rubens L.), Festuca arundinacea Schreb., Hordeum murinum L., H. vulgare L., Vulpia ciliata Dumort., Medicago rugosa Desr., M. sativa L., Trifolium subterraneum L., T. incarnatum L., Phacelia tanacetifolia Benth., Sinapis alba L., and Pinus sylvestris L., on the germination and early growth of three troublesome weeds (Conyza bonariensis (L.) Cronquist, Aster squamatus (Spreng.) Hieron, and Bassia scoparia (L.) A. J.). The different in vitro bioassays showed that aqueous extracts of some species significantly inhibited or reduced germination and root and shoot growth of the target weed species in a dose-response manner. Germination of A. squamatus and C. bonariensis was reduced by 100-80% by the different extracts applied at 50% concentration and completely blocked at 100% concentration, except for M. rugosa extract, to which both species showed less sensitivity. Root elongation of A. squamatus was inhibited under every extract and concentration, whereas C. bonariensis root growth showed only some tolerance to the crude extracts of F. arundinacea and P. sylvestris. Bassia scoparia was relatively tolerant to the aqueous plant extracts, except for T. subterraneum crude extract, which reduced total germination by 80%; otherwise, B. scoparia showed higher general sensitivity of shoot growth than the other two weed species. The chemical profiles of phenolic compounds of the aqueous extracts were obtained and identified by HPLC-DAD, the phenolic profiles of H. murinum, V. ciliata, and M. rugosa being reported in this work for the first time. Using stepwise regression, the influence of certain phenolic compounds from the aqueous extracts on the germination and early growth of weeds was predicted. Among other significant compounds, the flavonoid naringenin identified in T. subterraneum aqueous extract at 8.09 μg·mL–1 was predicted to underlie its specific phytotoxicity on B. scoparia germination. These results support the use of cover crops and mulches in weed management and can help to select the most suitable species to adopt according to the target weed species. Highlights- The phytotoxic nature of the aqueous extracts of twelve conventional and novel cover crops and mulch species was demonstrated in vineyards’ three troublesome weed species. - Phenolic acids and flavonoids of the twelve aqueous extracts were identified and quantified by HPLC-DAD, and, by regression analysis, some allelochemicals were postulated as responsible for the phytotoxic effects. - The water-soluble phenolic profiles of three potential cover crops, namely Hordeum murinum, Vulpia ciliata, and Medicago rugosa, are reported for the first time. - In vitro germination and early root growth of Conyza bonariensis and Aster squamatus were almost entirely restricted by any of the twelve plants’ aqueous extracts and presumably by the joint action of their particular allelopathic compounds. - Bassia scoparia germination was relatively much less sensitive to the extracts, except for Trifolium subterraneum, for which the flavonoid naringenin was predicted to underlie its specific phytotoxicity.

The intersection of integrated pest management and soil quality in the resistant weed era

Agricultural producers and scientists have long recognized both beneficial and detrimental aspects of soil tillage. With the development and adoption of herbicide-resistant crops, particularly glyphosate-resistant crops, herbicides such as glyphosate replaced the need for tillage either before or after crop planting. Thus, tillage has become less important for weed management and has been a primary enabler for the success of the majority of conservation production systems. Currently, herbicide-resistant and troublesome weeds are continually challenging agricultural decisions throughout the world. Conservation tillage hectarage is at constant risk of being converted to higher-intensity tillage systems due to lack of weed control. The shift to higher-intensity tillage facilitates the burial of weed seed through the use of inversion tillage and/or of surface tillage to facilitate pre-plant incorporated and pre-emergence herbicides for control of herbicide-resistant or troublesome weeds, especially in non-irrigated production. For example, Palmer amaranth (Amaranthus palmeri) has become the dominant weed problem in United States row crop production because of evolved resistance to glyphosate. Inversion tillage was clearly demonstrated to be an effective tool in helping the management of this weed. However, there is no question that most tillage operations promote soil loss, adversely affect (lower) surface water quality, and negatively impact soil productivity. Depending on the severity of the herbicide-resistant or troublesome weed infestation, multiple strategies involving the integration of cultural and chemical weed control will be needed to overcome the need for tillage. Utilizing high biomass conservation tillage systems, such as those used extensively in South America and introduced to the United States, can help reduce the emergence of weeds by suppressing weed germination and growth. A dense mat is formed on the soil surface when the winter cover crop is planted early and managed for maximum growth. Because weed emergence and growth are suppressed by the physical barrier and shading provided by the residue, more residue increases weed control. Conservation tillage systems that minimize soil disturbance (direct seeding or minimum tillage) can further reduce weed seed germination. In addition, allelopathy plays a role in weed suppression, but quantifying allelopathic effects in applied research is rarely accomplished. Creative research programs have been developed that meet conservation compliance requirements and, at the same time, judiciously use tillage as an element for the management of resistant or troublesome species. Similar programs are needed to help manage herbicide-resistant or troublesome weed species in other regions and cropping systems. Further research is critically needed when few or no other options are available to ensure the economic viability of farming operations while addressing long-term soil quality concerns. Highlights - Conservation tillage hectarage is at constant risk of being converted to higher-intensity tillage systems due to lack of weed control. - Most tillage operations promote soil loss, adversely affect surface water quality, and negatively impact soil productivity. - Creative research programs have been developed that meet conservation compliance requirements and, at the same time, judiciously use tillage as an element for the management of resistant or troublesome species. - Further research is critically needed when few or no other options are available to ensure the economic viability of farming operations while addressing long-term soil quality concerns.

Rye (<em>Secale cereale</em> L.) and squarrose clover (<em>Trifolium squarrosum</em> L.) cover crops can increase their allelopathic potential for weed control when used mixed as dead mulch

Cover crops are essential tools in agro-ecosystems for reducing the reliance on synthetic inputs and associated environmental risks. Alongside their benefits to soil fertility, cover crops can control weeds by their competitive and allelopathic attributes. Laboratory and field experiments were conducted to assess the allelopathic potential of two cover crop species, rye (Secale cereale L.) and squarrose clover (Trifolium squarrosum L.), alone or in a mixture, on seed germination and growth of arable weeds. Aqueous extracts of the two cover crops and their mixture were tested in a bioassay on Conyza canadensis (L). Cronq., Amaranthus retroflexus L. and Digitaria sanguinalis (L.) Scop. In vitro effects of aqueous extracts varied in a dose-dependent manner, with cover crops and weed species. All three extracts were able to reduce the germination of A. retroflexus (–87%) considerably. Inhibitory effects by rye and mixture extracts on radicle growth of all weed species ranged between 51 and 82%. Rye extract was the best at reducing shoot length of C. canadensis and D. sanguinalis (–39 to 44%), while squarrose clover was more effective on A. retroflexus (–79%). Plant extracts also delayed the germination time of weed species with a substantial effect of the mixture on C. canadensis seeds. In the field experiment, no significant weed suppression was provided by cover crop residues incorporated as green manure compared to control plots, despite tillage being more effective in reducing weed density than no-till. Still, the mulch of the mixture controlled weed emergence significantly better than single cover crop mulches. The chemical characterization of cover crop residues, both shoots and roots, revealed a notable richness of allelopathic phenolic acids and flavonoids, which may constitute potential natural herbicides through slow decomposition. From the analysis of the aqueous extracts, other non-analysed and/or unidentified water-soluble allelopathic compounds should underlie the phytotoxicity observed in vitro, at least for rye. For cover crop mixture, positive interactions among plant materials leading to a better release of allelochemicals and weeding effectiveness are discussed according to chemical profiles and field data. Our study demonstrated the allelopathic activity of the cover crops and their potential to be included in weed management strategies according to cropping system needs. Additional trials are needed to confirm the performance of cover crop residues under field conditions. Highlights - Rye and squarrose clover are cover crops with potential allelopathic effects. - Aqueous extracts of residues of rye, squarrose clover, and their mixture reduced and/or slowed weed germination of A. retroflexus and C. canadensis in the in vitro bioassays. - Depending on the concentration of residues, the aqueous extracts had inhibitory effects on radicle and shoot growth of A. retroflexus, C. canadensis, and D. sanguinalis. - The mulch of a mix of rye and squarrose clover under field conditions suppressed weeds better than the single species.

Stale seedbed preparation for sustainable weed seed bank management in organic cropping systems

Stale seedbed preparation is a neglected agronomic strategy used to decrease weed seed banks. The experiments aimed to verify the quantity-qualitative seed bank reduction after different soil tillage typologies: rotary cultivator, rotary harrowing and spike tooth harrowing (tillage depth in each case uniformed to about 15 cm). Tillage was carried out during the spring-summer period, with five tillage sequences spaced about 30-40 days. The weed seedbank analysis (10-30 cm) showed that beyond a 10 cm soil depth, the buried seeds were unaffected irrespective of the kind of soil tillage since no seed depletion was observed. In contrast, weed seed bank was heavily depleted in the shallowest soil layer (0-10 cm) due to the germination trigger induced by the soil aeration and by the consequent increase of oxygen availability after tillage. This seed bank reduction, was proportional to the degree of soil crumbling induced by the different tillage methods and it was higher in the case of the smaller soil clods size. Each weed species showed the highest emergence dynamics when soil tillage was carried out during the periods most suitable to meet the respective thermal requirements. Indeed the earliest soil tillage in April triggered germination and emergence of microthermal weeds, while those carried out in May and June triggered the emergence dynamics of weeds characterized by higher thermal requirements. The emergence rate, after the stale seedbed preparation, showed high values overall in the case of deep soil crumbling. In addition the extent of soil crumbling was positively related to the biodiversity of the emerged weed communities. The weed species that were the least sensitive to stale seedbed preparation were those characterized by small seeds and consequently those species would be more difficult to reduce through stale seedbed preparation.

Nutrient availability and pH level affect germination traits and seedling development of Conyza canadensis

Reducing pesticide application in agricultural land is a major challenge for the twenty-first century. Responses of weed seed’s germination and seedling’s early development to chemical soil conditions around the seed may be a promising way to aid weed control in a no-till system. Thus, the objective of this work was to test, under controlled conditions, whether different chemical conditions affect the germination and development of horseweed [Conyza canadensis (L.) Cronquist]. We used, as treatment, solutions containing different nutrients (P, K, Ca, and Mg), separately and in combination, and at two pH levels (4.8 and 6.5). Phosphorus alone inhibited horseweed seed germination at ~ 7 times while had ~ 4 times reduction in final germination percentage and germination speed index for both pH tested. Other nutrients tested had a no-effect in germination speed index compared to the control treatment. Potassium alone or associated with other ions (P, Ca, and Mg) at pH 4.8 had a synergistic effect on seedling development (root and shoot length). In the same way, K associated with Mg was synergistic to the root length at pH 6.5. Seeds in the control treatment (distilled water) presented a high germination speed index at pH 6.5, while at low pH this parameter was higher when in association with KMg, PMg and Ca. The findings demonstrate that seed germination traits and seedling development of horseweed depend on nutrient kind exposure and pH conditions in the seed environment. This work suggests that adequate topsoil management (i.e., pH and nutrient availability) may aid to reduce weed germination, because, it consists of an important factor of weed occurrence in agricultural areas.

Weed Suppression, Nitrogen Availability, and Cabbage Production Following Sunn Hemp or Sorghum-sudangrass

Cover crops included in a crop rotation can help increase nitrogen (N) availability to subsequent crops, raise soil organic matter, and suppress emergence and growth of various weed species. However, weed suppression by cover crops has mostly been investigated shortly after cover crop termination and not over a longer period spanning into the next cropping season. The effects of sunn hemp (Crotalaria juncea) and sorghum-sudangrass (Sorghum ×drummondi) planted the previous year on N availability before transplanting of late summer cabbage (Brassica oleracea), weed germination and growth, and cabbage yield was examined in field studies conducted in 2018 and 2019 at Pittstown, NJ. Results established that there was little evidence for a functional difference in soil N availability for fall cabbage production because of previous cover crop type. Heavy rainfall events both years may have caused major losses of available N that might otherwise be expected to come from N mineralization of residues of legume cover crop like sunn hemp. During the cover crop season, smooth pigweed (Amaranthus hybridus) and common lambsquarters (Chenopodium album) dry biomass was 77% and 82% lower, respectively, in sorghum-sudangrass compared with sunn hemp plots. The subsequent season following sorghum-sudangrass cover crop, dry biomass of broadleaf weeds was lower by 74% and 56% in June and July, respectively, compared with preceding sunn hemp. Smooth pigweed, common lambsquarters, and hairy galinsoga (Galinsoga quadriradiata) were the weed species most consistently affected by preceding sorghum-sudangrass cover crop with biomass decreased by up to 80%, 78%, and 64%, respectively. Thus, it appears that sorghum-sudangrass can provide suppression of some broadleaf species over a relatively long period and is indicative of sorghum-sudangrass allelopathic activity. On the contrary, density and biomass of grassy weeds as well as commercial yield of transplanted cabbage were unaffected by the preceding cover crop. These results suggest that sorghum-sudangrass cover crop could be integrated to transplanted cole crop rotation for providing weed suppression benefits without altering crop yield in New Jersey organic vegetable cropping systems.

Influence of sugarcane straw on weed germination control


 This research studied the effectiveness of herbicide treatments in weed control and during different periods of emergence, when applied to varying amounts of straw. The experiment was conducted in a greenhouse with pre-emergent herbicides: amicarbazone, metribuzin, indaziflam, isoxaflutole, amicarbazone + indaziflam, metribuzin + indaziflam, and isoxaflutole + indaziflam, against three species (Sorghum halepense, Rottboellia exaltata, and Mucuna aterrima). The experimental design was completely randomized in a 5x4 factorial scheme, with five amounts of straw (0, 1, 2, 3, and 5 t/ha) and four periods of weed emergence (0, 30, 60, and 90 days after treatments). The residual control of indaziflam was influenced by the amount of straw. Metribuzin presented a low residual control, while isoxaflutole was not affected by the amount of straw. Amicarbazone offered residual control for Mucuna aterrima. The association between indaziflam + isoxaflutole displayed a suitable residual control against Sorghum halepense and Rottboellia exaltata. The association of indaziflam + metribuzin adequately controlled Mucuna aterrima and Sorghum halepense. herbicide physical-chemical characteristics can influence their performance, and the association of products may increase residual and weed spectrum control.
 Highlights
 
 This partial or total removal of remaining sugarcane straw from the soil surface alters weeds dynamics in sugarcane fields. In this situation we have monocot and dicot weeds infesting the sugarcane crops.
 Among these species, some plants are even more difficult to control, such as Sorghum halepense, Rottboellia exaltata, and Mucuna aterrima
 Indaziflam herbicide presented a better performance in controlling monocotyledonous plants than eudicot plants.
 The herbicides amicarbazone and metribuzin presented adequate control of Mucuna aterrima despite having lower residual control.
 The association of indaziflam + metribuzin, resulted in satisfactory results for Mucuna aterrima, Sorghum halepense, and Rottboellia exaltata.

Response Of Weed Seed Germination From Fruit Crops Planting Soil To Application Of Metsulfuron Methyl Herbicide And Rice Husk Biochar

This study aims to determine the effect of the pre-emergence application of the herbicide metsulfuron methyl on the soil mixed with rice husk biochar to the germination of weeds. This study used a factorial completely randomized design (CRD) with two levels of herbicide metsulfuron methyl (0 gr/ha and 300 gr/ha) and four levels of rice husk biochar (0%, 5%, 10%, and 15% of the total weight of the planting medium). The parameters observed were the number of weeds, wet weight of weeds, and dry weight of weeds. The results showed that the interaction of the herbicide metsulfuron methyl and rice husk biochar had no significant effect on weed germination. The single treatment of the herbicide metsulfuron methyl had a significant effect on the number of weeds, wet weight of weeds, and dry weight of weeds. Herbicides can reduce the number of germinated weeds, wet weight of weeds, and dry weight of weeds by 39.3%, 83.7%, and 84.7%, respectively. While the single treatment of rice husk biochar showed a significant effect on the number of weeds and dry weight of weeds. The 15% treatment of rice husk biochar was the best to reduce the number of germinated weeds, namely 76.6%. Rice husk charcoal has the potential to be an alternative to suppress weed seed germination in the soil without using herbicides.

Characterization of clopyralid resistance in lawn burweed (Soliva sessilis)

Soliva sessilis is a troublesome annual weed species in New Zealand turfgrass. This weed has been controlled selectively in New Zealand turfgrass for many years using pyridine herbicides such as clopyralid. However, in some golf courses, the continuous application of pyridine herbicides has resulted in the selection of S. sessilis populations that are resistant to these herbicides. This study focuses on a clopyralid-resistant population of S. sessilis collected from a golf course with a long history of clopyralid applications. The resistant phenotype of S. sessilis was highly resistant to clopyralid (over 225-fold). It was also cross-resistant to dicamba, MCPA and picloram but not mecoprop. The level of resistance to dicamba was high (7-14-fold) but much lower (2-3-fold) for both MCPA and picloram. The phenotype was morphologically distinct from its susceptible counterpart. Individuals of the clopyralid-resistant phenotype had fewer lobes on their leaves and were slightly larger compared to the susceptible phenotype. Resistant individuals also had a larger leaf area and greater root dry weight than the susceptible plants. An evaluation of internal transcribed spacer (ITS) regions confirmed that clopyralid-resistant phenotypes are conspecific with S. sessilis. In summary, the cross-resistance to several auxinic herbicides in this S. sessilis phenotype greatly reduces chemical options for controlling it; thus, other integrated management practices may be needed such as using turfgrass competition to reduce weed germination. However, the morphological differences between resistant and susceptible plants make it easy to see, which will help with its management.

ВПЛИВ СИСТЕМ ОСНОВНОГО ОБРОБІТКУ ҐРУНТУ ТА УДОБРЕННЯ ІЗ ВИКОРИСТАННЯМ ПОБІЧНОЇ ПРОДУКЦІЇ НА ЗАБУР’ЯНЕНІСТЬ КУЛЬТУР СІВОЗМІНИ

The results of research on the study of the influence of soil processing systems and fertilizer using co-product for sown clogs and the yield of agricultural plants in a short-growing crop rotation are given. The influence of soil processing systems and fertilizer using co-products for sown clogs and the yield of agricultural plants in a short-live crop rotation is investigated. It has been established that on dark gray soil use in crop rotation of unifituted soil treatment systems contributes to an increase in the level of sown clogging (barley of the corn on grain at 1.4–1.6, wheat winter of winter of winter in 1.4–1.8 times) Due to the accumulation of the main amount of weed seeds in the upper soil layer. The system of fertilizer with by-products at the beginning of the vegetation of plants stimulates the germination of weeds. On average, over the years of research, the abundance of weeds in cropping crops at the beginning of vegetation when using unifituted soil treatment systems was 213–362 pcs/m2, dismissal – 94–108 pcs/m2, and before harvesting was noted a decrease in clogging, respectively, 29–57 pcs/m2, 10–13 pcs/m2. The air-dry weight of the weeds of the highest was with surface soil processing using co-product fertilizer (81.3–85.4 g/m2) relatively with dumping soil treatment (21.7–23.3 g/m2). The highest grain grain of wheat winter – 6.91 and 6.50, corn – 11.47 and 11.74, barley of the yarn – 5.37 and 5.13 and the rape of winter – 3.08 and 3.19 t/ha received when Discalled by 20–22 cm and shallow 10–12 cm soil processing system. With a 6–8 cm surface, the yields of crops decreased by 1.45, 3.66, 1.69 and 0.31 t/ha correspond to plants. A significant reason for reducing plant yields in versions with unifituted soil treatment systems served as a clogging factor, because the level here was higher than when the soil processing.

Allelopathic Potential of Etlingera coccinea (B.) Sakai & Nagam on Seed Germination and Growth of Mung Bean and Siam Weed

Etlingera coccinea, a native Borneon Zingiberaceae are found to exert allelopathic effect on some weed species. The objective of this study is to investigate the allelopathic effects of hexane (80%), methanol (80%), ethyl acetate (80%) extracts from the dried powder of both stem and leaf of E. coccinea on mung bean (Vigna radiata) and Siam weed (Chromolaena odorata). The phytochemical screening of both stem and leaf crude extracts elicited saponin, tannin, flavonoid, and terpenoid, which are targeted bioactive compounds for allelopathy. The allelopathic activity was assessed by evaluating their effects on seed germination and percentage of radicle and shoot growth. The results showed that both stem and leaf extracts have a suppressive effect on the mung bean development during in-vitro bioassay. The methanolic extracts of both stem and leaf showed the most significant suppression (100%) than other solvent extracts. In the pot experiment, the methanolic stem extracts suppressed the Siam weed’s germination by 57 ± 0.13% and the methanolic leaf extracts suppressed the growth by 46 ± 0.29%. The present study shows that E. coccinea methanolic extract has the potential as bio-herbicide.