Echinochloa Colona Research Articles

Persicaria lapathifolia Essential Oil: Chemical Constituents, Antioxidant Activity, and Allelopathic Effect on the Weed Echinochloa colona

The exploration of new green, ecofriendly bioactive compounds has attracted the attention of researchers and scientists worldwide to avoid the harmful effects of chemically synthesized compounds. Persicaria lapathifolia has been reported to have various bioactive compounds, while its essential oil (EO) has not been determined yet. The current work dealt with the first description of the chemical composition of the EO from the aerial parts of P. lapathifolia, along with studying its free radical scavenging activity and herbicidal effect on the weed Echinochloa colona. Twenty-one volatile compounds were identified via GC–MS analysis. Nonterpenoids were the main components, with a relative concentration of 58.69%, in addition to terpenoids (37.86%) and carotenoid-derived compounds (1.75%). n-dodecanal (22.61%), α-humulene (11.29%), 2,4-dimethylicosane (8.97%), 2E-hexenoic acid (8.04%), γ-nonalactone (3.51%), and limonene (3.09%) were characterized as main compounds. The extracted EO exhibited substantial allelopathic activity against the germination, seedling root, and shoot growth of the weed E. colona in a dose-dependent manner, showing IC50 values of 77.27, 60.84, and 33.80 mg L−1, respectively. In addition, the P. lapathifolia EO showed substantial antioxidant activity compared to ascorbic acid as a standard antioxidant. The EO attained IC50 values of 159.69 and 230.43 mg L−1, for DPPH and ABTS, respectively, while ascorbic acid exhibited IC50 values 47.49 and 56.68 mg L−1, respectively. The present results showed that the emergent leafy stems of aquatic plants such as P. lapathifolia have considerably low content of the EO, which exhibited substantial activities such as antioxidant and allelopathic activities. Further study is recommended to evaluate the effects of various environmental and climatic conditions on the production and composition of the EOs of P. lapathifolia.

Herbicide in Weed Management of Wheat (Triticum aestivum L.) and Rainy Season Rice (Oryza sativa L.) under Conservation Agricultural System

Conservation agriculture (CA) based practices are gaining popularity in smallholder farming systems recently because they ensure soil quality and soil health, and they also reduce the total cultivation costs. However, weeds are a major hinderance to achieving the desired yield of crops in cereal-based cropping systems under CA-based practices. Proper weed management is a big challenge for crop growers to reduce the labor demand and cost of production. Considering these burning issues, a field study was done with a CA-based rice–wheat–mung bean (Vigna radiata L.) cropping pattern in two consecutive years (2017–2018 and 2018–2019). The study aimed to understand the types and distribution of weeds in non-puddled rice fields and also in strip-planted wheat fields in sandy loam textured soil with low organic matter (0.87%) content. Furthermore, we also tried to discover the most economic and effective ways to manage weeds in both cereals of the cropping pattern. The performance of two herbicides—pendimethalin (as pre-emergence) and carfentrazone–ethyl + isoproturon (as post-emergence)—for strip-planted wheat and three herbicides—two pre-emergence herbicides pretilachlor and pyrazosulfuron–ethyl as well as one post-emergence herbicide, bispyribac–sodium—for non-puddled rainy season rice were evaluated, where the ‘weedy check’ and ‘weed free’ treatments were considered as a control. In a two-year field experiment, eight weed species in the strip-planted wheat field during the first year and fourteen species in the second year were identified. Among them, three grasses such as Cynodon dactylon (L.) Pers., Digitaria sanguinalis (L.) Scop. and Echinochloa colona (L.) Link and one broadleaf weed Physalis heterophylla (L.) Nees, were found to the dominant in both years. During the first season, the dominant weed species in strip-planted wheat was Physalis heterophylla (L.); Digitaria sanguinalis (L.) Scop was dominant in the second year. In a non-puddled field of rainy season rice, eleven weed species were found in the first year and twelve species were found in the second year. Among the weed species, four types of grasses (Cynodon dactylon (L.) Pers., Leptochloa chinensis (L.) Nees, Echinochloa colona (L.) Link and Leersia hexandra (Sw.), one sedge (Fimbristylis miliacea (L.) Vahl) and four broadleaf weed species (Ludwigia decurrens (Walter), Jussiaea repens (L.), Enhydra fluctuans (Lour) and Alternanthera sessilis (L.) R.Br. ex DC.) were found the common in both years. The most dominant weed in non-puddled rainy season rice was Leptochloa chinensis (L.) for the first year and Alternanthera sessilis (L.) for the second year. The study revealed that the sequential application of pendimethalin as pre-emergence treatment followed by carfentrazone–ethyl + isoproturon as post-emergence treatment were most effective and economically viable for weed control in strip-till wheat because they achieved the highest grain and straw yields. For weed management in non-puddled rainy season rice, the herbicide pyrazosulfuron–ethyl applied as pre-emergence treatment and bispyribac–sodium as the post-emergence application were found to be the most effective combination to obtain a desirable yield.

Genotypic–phenotypic diversity and distinctiveness among Magnaporthe grisea isolates from rice and weed Echinochloa colonum

AbstractRice blast disease caused by Magnaporthe grisea (Hebert) Barr is a serious biotic stress causing worldwide yield loss in cultivated rice. As high as 75% to 100% crop damage has been recorded in India. The disease is manifested by the appearance of lesions of various colours, size and spore liberation ability. The pathogen also infects 50 other hosts including weeds and grasses as secondary hosts. Information on genetic diversity, host specificity and phenotypic characters of the pathogens needs to be explored for better management of the disease. Therefore, fourteen M. grisea isolates from rice host and six isolates from weed host Echinochloa colonum were collected from three locations of coastal Odisha. Culture studies revealed that most isolates from virulent lesions had both black colour mycelia and pigmentation (B/B pattern). All the twenty M. grisea isolated produced bigger conidia with size ranged from 21.1–33.0µm to 7.6–12.7µm (length and breadth). Isolates from virulent lesions produced higher number of conidia. Isolates from weed had long and slender type conidia. Molecular genetic studies based on repetitive element Pot2 and random amplified polymorphic DNA (RAPD) could separate isolates on the basis of host plant and virulence of source lesion. Isolates from weed were consistently placed in separate group where presence and absence of bands specific to this group were observed. Rep‐PCR based on Pot2 amplified polymorphic DNA fragments where bands at 1750bp were specific to isolates from weed. Similarly, amplification specific to weed isolates was obtained at 1200bp by primer OPB10 in RAPD PCR. Amplification at these base pairs may be used for the development of markers to distinguish M. grisea from rice and weed. This is the first report of utilization of rep‐PCR and RAPD to distinguish M. grisea among rice and Echinochloa colonum in this region.

Fate and adaptive plasticity of heterogeneous resistant population of Echinochloa colona in response to glyphosate

Understanding the fate of heterogenous herbicide resistant weed populations in response to management practices can help towards overcoming the resistance issues. We selected one pair of susceptible (S) and resistant (R) phenotypes (2B21-R vs 2B21-S and 2B37-R vs 2B37-S) separately from two glyphosate resistant heterogeneous populations (2B21 and 2B37) of Echinochloa colona and their fate and adaptive plasticity were evaluated after glyphosate application. Our study revealed the glyphosate concentration required to cause a 50% plant mortality (LD50) was 1187, 200, 3064, and 192 g a. e. ha−1 for the four phenotypes 2B21-R, 2B21-S, 2B37-R, and 2B37-S respectively. Both S phenotypes accumulated more biomass than the R phenotypes at the lower application rates (34 and 67.5 g a. e. ha−1) of glyphosate. However, the R phenotypes generally produced more biomass at rates of glyphosate higher than 100 g a. e. ha−1 throughout the growth period. Plants from the R phenotypes of 2B21 and 2B37 generated 32% and 38% fewer spikes plant−1 than their respective S counterparts in the absence of glyphosate respectively. The spike and seed numbers plant-1 significantly higher in R than S phenotypes at increased rates of glyphosate and these relationships were significant. Our research suggests that glyphosate-resistant E. colona plants will be less fit than susceptible plants (from the same population) in the absence of glyphosate. But in the presence of glyphosate, the R plants may eventually dominate in the field. The use of glyphosate is widespread in field, would favour the selection towards resistant individuals.

Diversity of Grass Species from Sendhwa Dist. Barwani (M.P.), India

The present study was aimed to determining Diversity of grass species of Sendhwa Dist. Barwani, Madhya Pradesh, India. Sendhwa is bestowed with unique diversity of ethnic culture and natural resource. The present study is based on diversity of grass species in Satpura region of Sendhwa Dist. Barwani, of Madhya Pradesh, India during the period of 2017-2020. This area is the representative of climax vegetation and rich in grass biodiversity. On the basis of grass utility three species are abundantly found along with 38 genera and 45 species are frequently occurred in Sendhwa dist. Barwani. The data from the primary and secondary sources resulted in the documentation of 45 species belonging to 38 genera. The study area has a rich species diversity of grasses. Present study observes some wild economically important grasses which are Brachiaria reptans (L.) Gard. & Hubb., Echinochloa colonum (L.) Link., Oryza rufipogon Griff., Pennesetum pedicelatum Trin. , Phragmites karka (Retz.) trin ex. Steud., Sporobolus capillaries Miq., Sorghum halepense (L.) Kuntz., Urochloa panicoides P.Beauv. This documentation will be helpful to the staff of Forest department and for better management of grasslands with special reference to wildlife habitat.

Utilization of the neighborhood design to evaluate suitable cover crops and their density for Echinochloa colona management.

Summer weed species, including Echinochloa colona, are becoming problematic in the eastern grain region of Australia, but cover crops can be useful to suppress weeds during the summer fallow period. The present study evaluated the growth and seed production of E. colona grown alone or with four and eight cover crop plants per pot (i.e., 80 and 160 plants m-2). Four legume (cowpea, lablab, pigeonpea, and soybean) and two grass (forage sorghum and Japanese millet) cover crops were used. Interference by cover crops reduced the height, the number of leaves and tillers, inflorescence number, seed production, and biomass of this weed than when it was grown alone. Cover crops differed in their ability to suppress the growth and seed production of E. colona. The effect of cover crop density on the studied attributes was non-significant in most cases. Pigeonpea as a cover crop was the least effective in suppressing the growth and seed production of E. colona. In general, leguminous cover crops exhibited less suppression of E. colona than grasses. Forage sorghum was most efficient in reducing the growth of this weed. Forage sorghum and Japanese millet reduced E. colona leaf and tiller numbers per plant by 90 and 87%, respectively. These cover crops reduced E. colona leaf number to only 17 per plant as against 160 per plant recorded without cover crops. Inflorescence number per E. colona plant growing alone was as high as 48. However, it was reduced by 20–92% when this weed was grown with cover crop plants. E. colona’s seed production was significantly suppressed by all the cover crops, except pigeonpea. Biomass of E. colona was suppressed largely by forage sorghum and Japanese millet compared to other cover crops. Among the cover crops, pigeonpea produced the lowest biomass of 11 g pot-1, and the highest biomass (114 g pot-1) was produced by forage sorghum. The study demonstrated the usefulness of cover crops, especially forage sorghum and Japanese millet, to suppress the growth and seed output of E. colona.

Junglerice (<em>Echinochloa colona</em> L.) seedling emergence model as a tool to optimize pre-emergent herbicide application

Junglerice (Echinochloa colona), one of the worst and most problematic weeds globally, causes significant economic losses due to yield loss and control cost increase. Taking into account that this weed emerges in approximately five months - from September to January -, and considering that reducing herbicide use is key in the current intensification of agricultural production systems, the present study was carried out under the hypothesis that there should be an optimal moment for pre-emergent herbicide application to achieve maximum weed control effectiveness and efficiency. Therefore, experiments were carried out from August 2016 to January 2021 in Pergamino, Buenos Aires province, Argentina, using a double-logistic emergence model of junglerice seedlings. Bicyclopyrone plus s-metolachlor, clomazone, and pyroxasulfone plus saflufenacil were applied at different times between 92 and 478 growing degree days (GDDs). Single applications between 348 and 399 GDD were observed to reduce junglerice seedling emergence by 85-99%, depending on the herbicide used. Such a seedling emergence reduction could be a convenient strategy to provide significant weed suppression in the field in combination with a competitive crop and within a sustainable production system. The results of the present study lead to the conclusion that using predictive models for pre-emergent herbicide applications ensures more effective use of herbicides and reduces the amounts of herbicides used and the risks of selecting herbicide-resistant junglerice populations. Highlights - Weed occurrence indirectly increases the number of herbicide applications in Argentina. - Reducing the number and volume of herbicide applications contributes to mitigating environmental impact in the short term. - There is a critical time during weed emergence in which chemical control via herbicide application is most effective. - Seedling emergence models are useful management tools to predict critical timing for weed control.

Integrated Use of Herbicide and Weed Mulch with Closer Spacing for Weed Management in Dry Direct Seeded Rice

The field experiments were conducted during the wet season of 2015 and 2016 (June to October) at Agricultural Farm, Institute of Agriculture, Visva-Bharati, Sriniketan, India to study the impact of integrated use of weed mulch and herbicide with closer spacing on weed growth and yield of direct seeded dry sown rice (Oryza sativa L.) cultivar MTU 1010. The experiment consisted of twelve treatments involving sole or integrated application of pre-emergence herbicide pendimethalin, mulching with water hyacinth and Indigofera weed and closer row spacing of 20 cm. The experiment was laid out in randomized block design with three replications. The experimental field was infested with 14 weeds out of which the predominant species were Cynodon dactylon, Echinochloa colona, Cyperus iria, Ludwigia parviflora, Hydrolea zeylanica, Spilanthes acmella, Alternanthera sessilis, Commelina benghalensis and Cyanotis axillaris. Integration of pendimethalin at 0.75 kg ha-1 and mulching with water hyacinth and closer spacing reduced weed dry weight by 75.92% over the weedy check. Integration of mulching with water hyacinth and closer spacing increased grain yield by 37.27 and 41.12% over sole application of pendimethalin and water hyacinth mulch, respectively. Weed competition resulted in 57% reduction in grain yield of rice. Hand weeding twice (25 and 45 DAS) had a significant effect on the reduction of weed density and dry weight and increasing grain yield of rice which was followed by application of pendimethalin 0.75 kg ha-1 along with mulching with water hyacinth at a closer row spacing of 20 cm.

Susceptibility of weed populations to glyphosate in banana plantations of the Department of Magdalena, Colombia

The prevalence and deficient control with glyphosate in some weeds in banana (Musa × paradisiaca L.) plantations in the Department of Magdalena, Colombia, have been evidenced. The susceptibility to glyphosate of prevalent weeds in farms with more than 10 yr of application of this herbicide was evaluated. Seeds and propagules of adult plants of five weedy species were collected from farms where deficient glyphosate control was observed (populations with possible resistance) and in areas not cultivated or free of herbicide use (susceptible populations). Under controlled conditions, seedlings obtained from 17 populations were treated with a commercial dose of glyphosate (1440 g acid equivalent [ae] ha-1) or twice this dose (2880 g ae ha-1). At 21 d after application, populations with a relative fresh weight and survival greater than 20% and visual control lower than 80% were categorized as resistant populations. To determine the resistance factor (RF) in the resistant populations, bioassays were performed with increasing doses of the herbicide (0, 720, 1440, 2880, 5760, and 11 520 g ae ha-1). Populations of Echinochloa colona (L.) Link and Melothria pendula L. were sensitive to both doses, while the populations of Commelina erecta L. and Syngonium podophyllum Schott were not controlled, confirming glyphosate-tolerant. Populations of Erigeron bonariensis L., from uncultivated areas was susceptible, while those from farms were resistant. Glyphosate-resistance was confirmed in two populations of E. bonariensis, with respective RF of 3.5 and 8.6. The repetitive application of glyphosate for weed control in the Magdalena banana farms has contributed to the prevalence of tolerant species and the appearance of herbicide-resistant weeds.

Composition of weed communities in seasonally flooded rice environments in East Africa is determined by altitude

Weeds are major biotic constraints to rice production worldwide. Compared to other sub-regions, weed communities of rice are not well described for East Africa and there is limited information on environmental factors affecting the distribution of species. This study aimed to address these knowledge gaps. Seasonally flooded rice production fields of 31 sites in Rwanda, Tanzania, Kenya and Uganda, across three altitude classes (Low: <200 m; Medium 200–1,000 m; High: >1,000 m), were surveyed for weed species using quadrats. Data analyses involved multivariate approaches, non-parametric Kruskal–Wallis tests and logistic regressions, followed by calculation of ranked species abundance and Shannon Wiener Index diversity analyses. A total of 286 weed species, belonging to 59 families, were recorded with 42 species not previously reported as lowland rice weed in the sub-region. Twenty-four species were identified as abundant across altitudes. Weed species diversity was higher at medium altitudes compared to high and low altitudes. Significant patterns of floristic distinction between altitudinal classes were observed, with 80% of dissimilarity. The high altitude was dominated by Echinochloa colona, Leptochloa squarrosa and Sphaeranthus suaveolens, the medium altitude was dominated by Crassula granvikii, Pycreus lanceolatus and Ageratum conyzoides while the low altitude was dominated by E. colona, Cyperus difformis and Cyperus esculentus. The weed species composition of seasonally flooded rice fields in East Africa is diverse. Identification of a limited group of (24) commonly abundant weed species as well as the articulation of altitude-specific weed species groups will facilitate the development of better tailored weed control programmes.

An ABCC-type transporter endowing glyphosate resistance in plants

Glyphosate is the most widely used herbicide in world agriculture and for general vegetation control in a wide range of situations. Global and often intensive glyphosate selection of very large weedy plant populations has resulted in widespread glyphosate resistance evolution in populations of many weed species. Here, working with a glyphosate-resistant (GR) Echinochloa colona population that evolved in a Western Australia agricultural field, we identified an ATP-binding cassette (ABC) transporter (EcABCC8) that is consistently up-regulated in GR plants. When expressed in transgenic rice, this EcABCC8 transporter endowed glyphosate resistance. Equally, rice, maize, and soybean overexpressing the EcABCC8 ortholog genes were made resistant to glyphosate. Conversely, CRISPR/Cas9-mediated knockout of the EcABCC8 ortholog gene OsABCC8 increased rice susceptibility to glyphosate. Subcellular localization analysis and quantification of glyphosate cellular levels in treated ABCC8 transgenic rice plants and isolated leaf protoplasts as well as structural modeling support that EcABCC8 is likely a plasma membrane-localized transporter extruding cytoplasmic glyphosate to the apoplast, lowering the cellular glyphosate level. This is a report of a membrane transporter effluxing glyphosate in a GR plant species, and its function is likely conserved in crop plant species.

Distribution and Impact of Parthenium (Parthenium hysterophorus L.) on Weed Species Diversity in Maize Fields in Western Gojjam Zone, Amhara National Regional State, Ethiopia

An investigative weed flora survey was conducted in parthenium-infested maize fields in West Gojjam Zone in 2019/2020. The objective was to investigate the distribution and impact of parthenium on species diversity. A survey was conducted on 90 fields using 2 m × 2 m (4 m2) quadrats (totally 270). A total of 110 weed species belonging to 27 families were identified out of these families. Asteraceae with 26 species (23.36%) and Poaceae with 18 species (16.36%) were abundant. The highest importance value (IV) was recorded by Ageratum conyzoides, Amaranthus hybridus, and Bidens pilosa, with 28.05, 19.18, and 13.16%, respectively, in no parthenium infestation level. The highest IV of 27.08, 17.71, and 16.44%, respectively, was shown by Ageratum conyzoides, Bidens pilosa, and Galinsoga parviflora with 27.08, 17.71, and 16.44%, respectively, in very low parthenium infestation level. Ageratum conyzoides (29.38%), Bidens pilosa (24.10%), and Parthenium hysterophorus (22.68%) had the highest IV in low parthenium infestation level. Parthenium hysterophorus (91.32%), Ageratum conyzoides (17.19%), and Echinochloa colona (16.34%) had high IV in moderate parthenium infestation level. It is concluded that Ageratum conyzoides, Bidens pilosa, Echinochloa colona, and Galinsoga parviflora were competitive over parthenium based on importance value, and this indicates to suggest parthenium as a biological management option.

Bioherbicidal Properties of Parthenium hysterophorus, Cleome rutidosperma and Borreria alata Extracts on Selected Crop and Weed Species

Natural product-based herbicides could be the effective alternatives to synthetic chemical herbicides for eco-friendly weed management. This research, therefore, was conducted to identify the phytotoxic properties of Parthenium hysterophorus L., Cleome rutidosperma DC. and Borreria alata (Aubl.) DC. with a view to introducing them as a tool for natural herbicide development. The methanol extracts of these plants were examined on the germination and growth of Zea mays L., Oryza sativa L., Abelmoschus esculentus (L.) Moench and Amaranthus gangeticus L., Oryza sativa f. Spontanea Roshev. (Weedy rice), Echinochloa colona (L.) Link., Euphorbia hirta L., and Ageratum conyzoides L. under laboratory and glasshouse conditions. A complete randomized design (CRD) with five replications and randomized complete block design (RCBD) with four replications were laid out for laboratory and glasshouse experiments, respectively. In the laboratory experiment, three plant extracts of 0, 6.25, 12.5, 50, and 100 g L−1 were tested on survival rate, hypocotyl, and radicle length of eight test plant species. No seed germination of A. conzyoides, E. hirta, and A. gangeticus were recorded when P. hysterophorus extract was applied at 50 g L−1. C. rutidosperma had the same effect on those plants at 100 g L−1. In the glasshouse, similar extracts and concentrations used in the laboratory experiments were sprayed on at the 2–3 leaf stage for grasses and 4–6 for the broadleaf species. Tested plants were less sensitive to C. rutidosperma and B. alata compared to P. hysterophorus extract. Among the weeds and crops, A. conyzoides, E. hirta, A. esculentus and A. gangeticus were mostly inhibited by P. hysterophorus extract at 100 g L−1. Based on these results, P. hysterophorus was the most phytotoxic among the tested plant extracts and could be used for developing a new natural herbicide for green agriculture.

Evaluation of induction of sethoxydim tolerance in maize (Zea mays L.) using salicylic acid as a safener

Introduction Herbicide safeners are chemical compounds used in combination with herbicides to make them safer that is, to reduce the effect of the herbicide on crop plants, and to improve selectivity between crop plants versus weed species being targeted by the herbicide. Herbicide safeners can be used to pretreat crop seeds prior to planting, or they can be sprayed on plants as a mixture with the herbicide. Salicylic acid (SA) and other salicylates are known to affect various physiological and biochemical activities of plants and may play a key role in regulating their growth and productivity. This hormone is synthesized by many plants and is accumulated in the plant tissues as the impact of unfavorable abiotic factors, contributing to the increase of plants resistance to stress. The aim of this study was to evaluate the efficacy of salicylic acid as a safener in corn tolerance to non-selective herbicide; sethoxydim, and the response of two weed species of johnsongrass (Sorghum halepense (L.) Pers.) and junglerice (Echinochloa colona (L.) Link) to it. Materials and methods The effect of sethoxydim (0.5, 22.5, 45, 94, 187 and 375 grams of active ingredient per hectare), and salicylic acid (in concentrations of 0, 1 and 2 mM) as factorial experiment in a completely randomized design were investigated to evaluate the response of fresh weight of corn, johnsongrass and junglerice. Salicylic acid treatment was used in seed priming form also. Pre-treatment of salicylic acid was done three days before herbicide spraying. Spraying different doses of sethoxydim herbicide in a complete five-leaf stage, was done using a mobile rail sprayer (Matabi, Spain) equipped with a flat-fan nozzle (8002), a delivery of 220 L ha-1 and a spray pressure of 200 kPa. To investigate the changes in photosynthesis in the treated plants, chlorophyll fluorescence of the leaves was evaluated on the sixth day after application of herbicides by PEA model fluorometer. Three weeks after spraying the herbicide, the shoots of the plants were removed from the surface of the pot and their fresh weight was measured. Analysis of variance was performed using generalized linear models (GLM) in SAS 9.2 software environment. Before performing analysis of variance to determine the normality of the data from Anderson-Darling test in Minitab ver. 17 were used, and in cases of non-normal data, Box-cox two-way power transformation was used in the same software. Analysis of variance, was performed as a factorial experiment for each plant to investigate the effect of the herbicide dose of sethoxydim and the concentration of salicylic acid and their interaction. The trend of wet weight changes of different species under the influence of different amounts of herbicide sethoxydim was investigated using the four parameters log-logistic equation.Results and discussion Dose-response curves of fresh weight of the treated plants showed that weeds were significantly affected by sethoxydim compared to corn. In all species, by increasing the concentration of salicylic acid, the ED50 increased. For all three levels of salicylic acid treatment, this parameter was the greatest in salicylic acid treatment as seed priming than others, and the lowest values of this parameter were observed for jungle rice. The highest amount of ED50 was 210 gram of active ingredient per hectare for corn sown with 2 mM / L salicylic acid treatment, and the lowest value was 31.5 gram of active ingredient per hectare for non-salicylic acid treatment in jungle rice. Kutsky’s curves for corn and weeds showed that Fluorescence chlorophyll was increased with the use of steroids herbicide, but salicylic acid treatment could reduce the rate of chlorophyll fluorescence, so that weed and corn after weeding the control without grass was observed at the lowest salicylic acid treatment (2 mM / L).Conclusions: In general, the results of this experiment showed that under the influence of sethoxydim, all three species of maize, johnsongrass and junglerice showed a positive response to salicylic acid foliar application. Therefore, in order to use salicylic acid as a safener, its seed treatment in corn should be used. Overall, the results showed that salicylic acid can be used as a stress reducer due to the use of sethoxydim in narrow-leaved plants. But as a safener we cannot use it universally and foliar spraying, because there is no differentiation in the response of crops and weeds. Therefore, in the use of salicylic acid as an immunizer for the sethoxydim, its seed treatment will give better results.

Recurrent Selection with Low Herbicide Rates and Salt Stress Decrease Sensitivity of Echinochloa colona to Imidazolinone

Weeds represent an increasing challenge for crop systems since they have evolved adaptability to adverse environmental conditions, such as salinity stress. Herbicide effectiveness can be altered by the quality of water in which the weed is growing. This research aimed to study the combined effect of salt stress and recurrent selection with a sublethal dose of imidazolinone herbicides in the shifting of the sensitivity of Echinochloa colona (L.) Link (junglerice) to imidazolinone herbicides. This study was divided into two experiments; in experiment I, three recurrent selection cycles were conducted in Pelotas/RS/Brazil with imazapic + imazapyr at 0.125× the field rate; and in experiment II, three recurrent selection cycles were conducted in Fayetteville/AR/USA with imazethapyr, at 0.125× the recommended dose. Salt stress was implemented by irrigation with 120 mM sodium chloride (NaCl) solution. The effective dose for 50% control of the population (ED50) values increased from the field population to the second generation (G2) after recurrent selection with a sublethal dose of imidazolinone combined with salt stress, supporting the hypothesis of reduced susceptibility by the combination of these abiotic factors. Recurrent exposure to a sublethal dose of imazapic + imazapyr or imazethapyr, combined with salt stress, reduced susceptibility of Echinochloa colona (L.) plants to imidazolinone herbicides.

Complete genome sequences and properties of Spartina mottle virus isolates from hybrid Bermuda grass (Cynodon dactylon × Cynodon transvaalensis)

AbstractFull genome sequences are presented for two isolates of Spartina mottle virus (SpMoV) from two accessions of the hybrid turf grass Cynodon dactylon × C. transvaalensis (Bermuda grass, green couch), originally from the USA but detected during post‐entry quarantine in Australia. Both isolates had a genome of 9,346 nucleotides, encoding a single polyprotein of 3,029 amino acids and predicted to be cleaved into 10 mature proteins. Phylogenetic analysis strongly supported placement in a new genus within the family Potyviridae. The isolates possess 715–780 × 11–12 nm flexuous virions and produce cylindrical (pinwheel) inclusions in infected cells. They were mechanically transmitted to several species in the Poaceae including Zea mays (maize, sweet corn), Chloris gayana (Rhodes grass), and Echinochloa colona (awnless barnyard grass).

Fecundity and Seed Dormancy Variation Within and Among Echinochloa Species

The Echinochloa genus contains two of the world's top five worst weeds. The persistence and weediness of Echinochloa spp. are partly due to its seed longevity and variable seed dormancy. In the USA, specifically in Arkansas, multiple species infest the same field in many cases. Persistence could vary across species and dormancy affects infestation level. Studies were conducted to evaluate the seed production potential and dormancy of Echinochloa species in the State. Ninety-four accessions were characterized in a common garden in Fayetteville, Arkansas, USA. The species were Echinochloa colona (L.) Link, E. crus-galli (L.) P. Beauv, E. muricata P. Beauv and E. walteri (Pursh). Only one accession was identified as E. walteri and was excluded from data analysis. Seeds were after-ripened for 6 months at room temperature and germinated at 32°C day/23°C night with 12-h daylength. Germination was monitored for 14 d. The Echinochloa species in Arkansas were predominantly E. colona (78%). E. colona had the highest seed production and the lowest seed dormancy among species. Dormancy within each species varied greatly, especially for E. colona, with a germination capacity (GC) of 41–99%. Only 2.7% of 73 E. colona accessions were dormant. E. crus-galli had 56–79% GC; 33% of the accessions were dormant. E. muricata had 2–39% germination, with all accessions considered dormant. E. colona had the highest fecundity, with 72,973 seeds per plant. This was 2.3- and 2.6x higher than that of E. crus-galli and E. muricata, respectively. High seed production and high germination capacity must have contributed to the dominance of E. colona among other Echinochloa species. E. muricata is expected to persist longer in the soil seedbank compared to E. colona and E. crus-galli. Seed production, dormancy and longevity will affect interspecies population dynamics in response to management tactics.

Effectiveness of Herbicide to Control Rice Weeds in Diverse Saline Environments

To mitigate environmental pollution and food contamination caused by inappropriate and excessive herbicide usage, most potent herbicides should be screened to control rice weeds. A research trial was executed for assessing the comparative efficacy of different herbicides to control rice field weeds and to evaluate the toxicity on rice under normal (distilled water) as well as different salinity levels (4 and 8 dS m−1). The study was designed to select the most potent herbicide and its appropriate dose for weed control of rice crop in coastal areas. Fourteen herbicidal treatments were included weed free crop, Pretilachlor (0.25, 0.50, 0.375 and 0.75 kg a.i. ha−1), Propanil + Thiobencarb (0.6 + 1.2, 0.9 + 1.8, 1.2 + 2.4 and 1.8 + 3.6 kg a.i. ha−1), Bensulfuron + MCPA (0.03 + 0.05, 0.045 + 0.075, 0.06 + 0.1 and 0.09 + 0.15 kg a.i. ha−1) and weedy check (control). The results revealed that all tested herbicides in higher than recommended doses for non-saline rice fields were effective in controlling Cyperus iria, Echinochloa colona (salt-tolerant) and Jussiaea linifolia but showed in light injury in rice plants grown in non-saline soils. These higher doses of herbicides recorded severe crop injury under saline conditions indicating their differential efficacy from normal non-saline conditions. Treatments including Pretilachlor (0.375kg a.i. ha−1), Propanil + Thiobencarb (0.9 + 1.8 kg ai/ha), Bensulfuron + MCPA (0.06 + 0.1 kg a.i. ha−1) and Pretilachlor (0.50 kg a.i. ha−1) remained superior in terms of weed control and grain yield production under all salinitylevels at TanjungKarang, Malaysia. It is concluded that herbicides respond differently under saline conditions and optimization of their doses potentially prevent herbicidal injury in rice plants.

Cabo Verde’s Poaceae Flora: A Reservoir of Crop Wild Relatives Diversity for Crop Improvement

Africa is home to important centers of origin and diversity of crop wild relatives (CWR), including many species adapted to adverse agroecological conditions, namely drought and poor soils. Plant genetic resources from Cabo Verde Islands have been poorly explored for their potential to supplement the genetic pool of cultivated species. In this paper we identify Cabo Verde’s CWR from the Poaceae family and provide a checklist of priority CWR taxa, highlighting those of particular conservation concern and the areas which should be the focus of the most intensive conservation efforts in these islands. Our results revealed that Cabo Verde archipelago is an important center of CWR diversity of West African crop millets, namely fonio (e.g., white fonio, Digitaria exilis, and black fonio, Digitaria iburua) and other African millets [e.g., pearl millet (Cenchrus americanus = Pennisetum glaucum), teff millet (Eragrostis tef), finger millet (Eleusine coracana), barnyard millet (Echinochloa colona), proso millet (Panicum miliaceum), and foxtail millet (Setaria italica)], which represent a diverse group of cereal crops, and important components in agriculture and food security of this country. Also, hotspot areas of diversity for in situ conservation were identified in Cabo Verde, as well as several populations occurring under extreme habitats conditions that are well adapted to drylands and poor soils. The evaluation of their potential for new ecologically important adaptive characteristics associated with tolerance to abiotic stresses is discussed. The survey of international Germplasm Banks revealed that very few accessions from Cabo Verde are conserved, contributing to the loss of genetic diversity of plant genetic resources in this archipelago. Particularly, the diversity of millets and the associated indigenous knowledge are critical for the food security and cultural identity of many poor farmers in Cabo Verde.

Impact of Herbicides on The Weeds and Quantity of Cotton (Gossypium barbadense L.) Variety Giza 94

Two field experiments were conducted during 2018 and 2019 to examined the effect of herbicides and hand hoeing on productivity and quality characters of Egyptian cotton (Gossypium barbadense L.)cultivar Giza 94. In summary, our work found that the highest effect on the fresh and dry weight of Portulaca olereceae and Echinochloa colonum was achieved by twice hand hoeing and pantira® + fuzilade® after 50 and 70 days of planting. Whereas, during the first season twice hand hoeing recorded the highest decreased value of the fresh weight of Portulaca olereceae (51.25a) after 50 days of planting followed by Pantira® + Fuzilade®(88.75 b). When recording the fresh weight for Echinochloa colonum the highest effect achieved twice hand hoeing (225.5 d and 470 b) after 50 and 70 days, respectively. During the second season 2019 after 50 days of planting the best results for biomass fresh weight achieved against Portulaca olereceae by twice hand hoeing (41.25c) and pantira® + fuzilade®(78.75b). whereas, the same results were achieved against the biomass fresh weight of Echinochloa colonum after 50 days by twice hand hoeing (21.55d) and pantira® + fuzilade®(25.9c). When determined the impact of herbicides on the chlorophyll, plant height, the number of bolls /plants, boll weight, fruit branches, weight 100 seeds and cotton of yield during seasons 2018 and 2019. The highest value was recorded by twice hand hoeing and pantira® + fuzilade for all growth characteristics and yield.