scholarly journals Morphological Variations in Caryopses and Seedlings of Two Grass Species of the Genus Dactyloctenium Willd.

2017 ◽  
Vol 9 (2) ◽  
pp. 301-306
Author(s):  
Ajai Kumar SINGH ◽  
Ayush Kumar SINGH ◽  
Manish Kumar SRIVASTAVA
Keyword(s):  
Weed Management ◽  
Leaf Blade ◽  
Leaf Sheath ◽  
Grass Species ◽  
Weed Species ◽  
Base Surface ◽  
Morphological Variations ◽  
Dactyloctenium Aegyptium ◽  
Morphological Differences ◽  
Grass Weed

Dactyloctenium aegyptium (L.) Willd. and D. aristatum Link. are common grass weeds of cultivated fields in many crops. The two grass weed species growing under same habitat showed characteristic morphological differences of caryopses and seedlings. The identification of weeds at seedling stage may be useful in weed and environment management. Under the light microscopy, features like colour, base, surface, scutellum and hilum of caryopses showed differences between the studied species. D. aegyptium had dark brown caryopses colour, while D. aristatum had grey colour. The base of D. aegyptium was truncate, while D. aristatumhad obtuse base. Both species had rugose surface but in D. aegyptium surface undulations were closely spaced whereas in D. Aristatum it was widely spaced. Similarly seedlings were found distinct with respect to coleoptile shape and size, first leaf sheath surface and first leaf blade shape and surface. D. aegyptium had oblong coleoptile whereas it was obovate in D. aristatum. The leaf sheath and leaf blade were recorded glabrous and hairy in D. aegyptium and in D. aristatum respectively. Both species studied hereby, showed remarkable differentiations in their characters, thus indicating that the morphological attributes of caryopses and seedling can be exploited taxonomically and for crop and weed management.

scholarly journals Seed shattering phenology at soybean harvest of economically important weeds in multiple regions of the United States. Part 2: grass species

Weed Science ◽  
2020 ◽  
pp. 1-19
Author(s):  
Lauren M. Schwartz-Lazaro ◽  
Lovreet S. Shergill ◽  
Jeffery A. Evans ◽  
Muthukumar V. Bagavathiannan ◽  
Shawn C. Beam ◽  
...  
Keyword(s):  
The United States ◽  
Grass Species ◽  
Annual Grass ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Shattering ◽  
Physiological Maturity ◽  
Rate Of Progression ◽  
Multiple Regions ◽  
Grass Weed

Abstract Seed shatter is an important weediness trait on which the efficacy of harvest weed seed control (HWSC) depends. The level of seed shatter in a species is likely influenced by agroecological and environmental factors. In 2016 and 2017, we assessed seed shatter of eight economically important grass weed species in soybean [Glycine max (L.) Merr.] from crop physiological maturity to four weeks after maturity at multiple sites spread across eleven states in the southern, northern, and mid-Atlantic U.S. From soybean maturity to four weeks after maturity, cumulative percent seed shatter was lowest in the southern U.S. regions and increased as the states moved further north. At soybean maturity, the percent of seed shatter ranged from 1 to 70%. That range had shifted to 5 to 100% (mean: 42%) by 25 days after soybean maturity. There were considerable differences in seed shatter onset and rate of progression between sites and years in some species that could impact their susceptibility to HWSC. Our results suggest that many summer annual grass species are likely not ideal candidates for HWSC, although HWSC could substantially reduce their seed output at during certain years.

WEED MANAGEMENT IN AEROBIC RICE: ROLE OF ESTABLISHMENT METHODS AND HERBICIDES

2017 ◽  
Vol 55 (1) ◽  
pp. 88-104
Author(s):  
SUSHMITA MUNDA ◽  
SANJOY SAHA ◽  
TOTAN ADAK ◽  
NITIPRASAD JAMBHULKAR
Keyword(s):  
Grain Yield ◽  
Weed Management ◽  
Aerobic Rice ◽  
Weed Species ◽  
Weed Density ◽  
Establishment Method ◽  
Dry Seasons ◽  
Grass Weed ◽  
Selection Of

SUMMARYWeed management in rice depends on establishment method and proper selection of herbicide. A field experiment was conducted during dry seasons of 2013 and 2014 to develop a robust strategy for effective weed management in aerobic rice system for tropical rice belts. The efficacy of post-emergent herbicides bispyribac-sodium, azimsulfuron and flucetosulfuron were evaluated under different rice establishment methods (row sowing, spot seeding and broadcasting). Grass weed species constituted 58–68% of the total weed density across the establishment methods in the weedy check treatment. The total weed density and weed biomass were lowest in spot seeding with azimsulfuron (35 g active ingredient (a.i.) ha−1) 30 and 60 days after sowing. Among herbicides, use of azimsulfuron caused the highest grain yield (5.2 Mg ha−1), realizing 72% increase in grain yield over the weedy check. Yields in row sowing and spot seeding were similar and the same was verified when comparing yields in plots treated with bispyribac-sodium and azimsulfuron. Based on our findings and considering both weed presence and grain yield, azimsulfuron in spot seeding can be recommended in aerobic rice.

scholarly journals Weed flora and weed management of field peas in Finland

2008 ◽  
Vol 14 (2) ◽  
pp. 189 ◽  
Author(s):  
J. SALONEN ◽  
T. HYVÖNEN ◽  
H. JALLI
Keyword(s):  
Weed Management ◽  
Chenopodium Album ◽  
Good Control ◽  
Organic Production ◽  
Grass Species ◽  
Weed Species ◽  
Stellaria Media ◽  
Cropping Practices ◽  
Weed Flora ◽  
Crop Stand

The composition of the weed flora of dry pea (Pisum sativum L.) fields and cropping practices were investigated in southwestern Finland. Surveys were done in 2002–2003 in 119 conventionally cropped fields and 64 fields under organic cropping. Herbicides were applied to 92% of conventionally cropped fields where they provided relatively good control but were costly. Weeds were controlled mechanically only in five fields under organic production. A total of 76 weed species were recorded, of which 29 exceeded the 10% frequency level of occurrence. The average number of weed species per field was 10 under conventional cropping and 18 under organic cropping. The most frequent weed species in both cropping practices were Chenopodium album, Stellaria media and Viola arvensis. Elymus repens was the most frequent grass species. The difference in species composition under conventional and organic cropping was detected with Redundancy Analysis. Under conventional cropping, features of crop stand and weed control explained 38.7% and 37.6% of the variation respectively. Under organic cropping the age of crop stand and field location (y co-ordinate) respectively explained best the variation. Weeds could be efficiently managed with herbicides under conventional cropping, but they represented a significant problem for organic production. Mixed cultivation of pea with cereals is recommended, particularly for organic cropping, as it favours crop competition against weeds.;

scholarly journals Conservation Agriculture: An Eco-Friendly System of Weed Management in Field Crops

2014 ◽  
Vol 3 (4) ◽  
pp. 91-100
Author(s):  
Tika Bahadur Karki ◽  
Jiban Shrestha
Keyword(s):  
Weed Management ◽  
Management Strategies ◽  
Conservation Agriculture ◽  
Grass Species ◽  
Weed Species ◽  
Conventional Agriculture ◽  
Perennial Weeds ◽  
Weed Dynamics ◽  
Agriculture Systems

Since the conservation agriculture (CA) is spreading across the globe, information on weed dynamics and their management under CA is needed. Here, an attempt has been made to summarize the recent research on weed dynamics and their management aspects in the CA systems. Changes in patterns of tillage, planting systems, and other management strategies can alter the soil environment and lead to shifts in weed populations. Weed patterns and populations are not always stable but vary with location, crop, and herbicides use. However, in many long-term conservation management studies, a general increase in perennial weeds and grass species has been observed. No tillage increased the weed population during first season and there after decreased. Residue has significantly reduced the number of weed species and population compared to conventional agriculture systems. The development of low-dose of non-selective pre and selective post emergence herbicides, and transgenic crops has greatly improved the feasibility of CA systems.DOI: http://dx.doi.org/10.3126/ije.v3i4.11733 International Journal of Environment Volume-3, Issue-4, Sep-Nov 2014Page: 91-100

scholarly journals Seed contamination in sheep: new investigations into an old problem

2018 ◽  
Vol 58 (8) ◽  
pp. 1538 ◽  
Author(s):  
J. E. Kelly ◽  
J. C. Quinn ◽  
P. Loukopoulos ◽  
J. C. Broster ◽  
K. Behrendt ◽  
...  
Keyword(s):  
Weed Management ◽  
Management Strategies ◽  
Production Capacity ◽  
Current Status ◽  
Future Research ◽  
Financial Loss ◽  
Weed Species ◽  
Sheep Production ◽  
The Impact ◽  
Grass Weed

Seed contamination significantly affects production capacity and animal welfare in Australian sheep flocks and causes considerable financial loss to producers and processors across sheepmeat value chains. Seven grass-weed species contribute to seed contamination in Australia, with barley grass (Hordeum spp.) identified as a key perpetrator. Herbicide resistance and variable dormancy emerging in southern Australian barley grass populations are thought to enhance its capacity for successful pasture invasion, further exacerbating the potential for seed contamination in sheep. The present article reviews the current literature regarding the impact and incidence of seed contamination on sheepmeat production, with particular reference to key grass-weed species prevalence across Australia. Data are presented on a recent incidence of carcass contamination across years, where incidence varied between 11% and 80% from 2009 to 2013, contracting to between 2% and 60% during 2014 and 2015. Key areas requiring future research are defined. Understanding the biology of key grass weeds, historical influences and economic consequences associated with seed contamination in sheep may assist in defining future risks to sheep production and improve weed management. Furthermore, examining more recent data describing the current status of seed contamination across Australia and the associations with causal weed species may aid the development of critical weed-management strategies in highly infested regions, subsequently limiting the extent of future seed contamination.

Gamma-rays in the development of rice lines tolerant to aryloxyphenoxypropionate herbicides.

2021 ◽  
pp. 285-289
Author(s):  
Alexander de Andrade ◽  
Augusto Tulmann Neto ◽  
Fernando Adami Tcacenco ◽  
Rubens Marschalek ◽  
Adriana Pereira ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Weed Management ◽  
Fatty Acid Biosynthesis ◽  
Amino Acid Position ◽  
Weedy Rice ◽  
Resistant Line ◽  
Weed Species ◽  
Excellent Control ◽  
Susceptible Control ◽  
Grass Weed

Abstract The aryloxyphenoxypropionate (APP) herbicides are graminicides with excellent control of many grass weed species, including weedy rice (Oryza sativa L.). These herbicides block fatty acid biosynthesis by inhibition of the enzyme acetyl-CoA carboxylase (ACCase) and cause death of the plant. Through induced mutation of rice seeds with gamma-rays, rice lines resistant to APP have been developed. Plant dose-response assays confirmed resistance to the APP herbicides quizalofop-p-ethyl and haloxyfop-p-methyl. The carboxyl-transferase (CT) domain fragments of ACCase from the resistant line and the susceptible control were sequenced and compared. A point mutation was detected in the amino acid position 2027. Results indicated that resistance to APP herbicides is a consequence of an altered ACCase enzyme that confers resistance. APP-resistant rice provides an option to improve the efficiency of weed management in rice crops.

On the Seedling Morphology of Some Grass Weeds – Echinochloa P. Beauv. (Poaceae)

2015 ◽  
Vol 38 (1) ◽  
pp. 47-50
Author(s):  
Ajai Singh ◽  
Ayush Singh ◽  
Rishi Sahu
Keyword(s):  
Leaf Blade ◽  
Uttar Pradesh ◽  
Leaf Sheath ◽  
Paddy Fields ◽  
Seedling Morphology ◽  
Morphological Attributes ◽  
Grass Weed

Present investigation deals with amplified seedling morphology of five grass weed taxa belonging to the genus Echinochloa P. Beauv. - E. colona, E. crus-galli, E. cruspavonis, E. frumentacea and E. stagnina, occurring commonly in Paddy fields of Vindhyan Region, Uttar Pradesh, India. Morphological attributes viz. venation and length of coleoptile, surface of scutellum, leaf sheath and leaf blade, collet and shape of leaf blade are found useful for the taxonomic differentiation of seedlings. Illustrations and key have also been provided.

WeedSOFT: Effects of Corn-Row Spacing for Predicting Herbicide Efficacy on Selected Weed Species

2007 ◽  
Vol 21 (1) ◽  
pp. 219-224 ◽  
Author(s):  
Shawn M. Hock ◽  
Stevan Z. Knezevic ◽  
William G. Johnson ◽  
Christy Sprague ◽  
Alex R. Martin
Keyword(s):  
Crop Yield ◽  
Weed Management ◽  
Crop Yields ◽  
Field Studies ◽  
Yield Potential ◽  
Control Treatment ◽  
Grass Species ◽  
Yield Reduction ◽  
Weed Species ◽  
The North

The ability to accurately estimate herbicide efficacy is critical for any decision-support system used in weed management. Recent efforts by weed scientists in the North Central United States to adopt WeedSOFT across a broad region have resulted in a number of regional research projects designed to assess and improve the predictive capability of WeedSOFT. Field studies were conducted from 2000 to 2002 in Nebraska, Missouri, and Illinois to evaluate herbicide-efficacy predictions made by WeedSOFT in two corn-row spacings. Following crop and weed emergence, input variables, such as weed densities and heights, were entered into WeedSOFT to generate a list of treatments ranked by predicted crop yields. The five treatments evaluated included those predicting highest crop-yield potential (recommended control treatment 1), a 10% yield reduction, a 20% yield reduction, a 10% yield reduction plus cultivation, and cultivation alone. These treatments were applied to corn grown in 38- and 76-cm rows. Generally, treatments applied in 38-cm rows had more accurate herbicide-efficacy predictions compared with 76-cm rows. WeedSOFT provided better control predictions for broadleaf than grass species. WeedSOFT provided excellent herbicide-efficacy predictions for the highest crop-yield potential, which indicates a good potential for practical use of this software for herbicide recommendations.

Integrating Sethoxydim into Soybean (Glycine max) Weed Management Systems

Weed Science ◽  
1985 ◽  
Vol 33 (1) ◽  
pp. 100-108 ◽  
Author(s):  
William B. Parker ◽  
L. Thompson ◽  
F. Michael Godley
Keyword(s):  
Glycine Max ◽  
Weed Management ◽  
Field Experiments ◽  
Management Systems ◽  
Grass Species ◽  
Weed Species ◽  
Nitrobenzoic Acid ◽  
Brachiaria Platyphylla ◽  
Panicum Dichotomiflorum ◽  
Postemergence Herbicides

On-farm field experiments were conducted in the Piedmont Plateau and Coastal Plain of North Carolina in 1981 and 1982 to investigate the integration of sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} with other chemical and cultural weed control tactics into soybean [Glycine max(L.) Merr.] weed management systems. Sethoxydim at 0.2 kg ai/ha provided control of broadleaf signalgrass [Brachiaria platyphylla(Griseb.) Nash. # BRAPP], large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA], and fall panicum [Panicum dichotomiflorumMichx. # PANDI) equal to control achieved with registered rates of the soil-applied herbicides alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl)acetanilide] and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine). Control of broadleaf weed species with the postemergence herbicides bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4-(3H)-one 2,2-dioxide] and acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} equaled or exceeded the control obtained with the soil-applied herbicides linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] and metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5-(4H)-one]. Applications of 0.22 kg/ha of sethoxydim 2, 3, 4, and 5 weeks after soybean planting provided season-long control of fall panicum and crabgrass in 1981. In 1982, crabgrass control was 88 to 99% up to 4 weeks after planting. Later applications provided inadequate control of the grass species. Variations in volume and pressure of application had no effect on control of 10-cm goosegrass [Eleusine indica(L.) Gaertn. # ELEIN] or broadleaf signalgrass with 0.2 kg/ha of sethoxydim. Increasing pressure increased control of 30-cm goosegrass and broadleaf signalgrass. Increasing volume increased only control of goosegrass. Bentazon and acifluorfen provided better control of broadleaf weeds when applied early than when applied late. In two of four experiments tank mixtures of sethoxydim and bentazon resulted in an initial decrease in grass control compared to corresponding sequential applications. Soybean yields were comparable, however.

Herbicidal Effects of Vinegar and a Clove Oil Product on Redroot Pigweed (Amaranthus retroflexus) and Velvetleaf (Abutilon theophrasti)

2009 ◽  
Vol 23 (2) ◽  
pp. 292-299 ◽  
Author(s):  
Glenn J. Evans ◽  
Robin R. Bellinder ◽  
Martin C. Goffinet
Keyword(s):  
Weed Management ◽  
Leaf Blade ◽  
Amaranthus Retroflexus ◽  
Shoot Tip ◽  
Growth Stages ◽  
Clove Oil ◽  
Blade Angle ◽  
Weed Species ◽  
Leaf Petiole ◽  
Redroot Pigweed

Weed management can be difficult and expensive in organic agricultural systems. Because of the potentially high cost of the natural product herbicides vinegar and clove oil, their efficacy with regard to weed species growth stages needs to be determined. A further objective was to identify anatomical and morphological features of redroot pigweed and velvetleaf that influence the effectiveness of vinegar and clove oil. Research was conducted on greenhouse-grown cotyledon, two-leaf, and four-leaf redroot pigweed and velvetleaf. Dose–response treatments for vinegar included 150-, 200-, 250-, and 300-grain vinegar at 318 L/ha and at 636 L/ha. Clove oil treatments included 1.7, 3.4, 5.1, and 6.8% (v/v) dilutions of a clove oil product in water (318 L/ha), and a 1.7% (v/v) dilution in 200-grain vinegar (318 L/ha). An untreated control was included. Separate plantings of velvetleaf and pigweed were treated with vinegar or clove oil and were used to study anatomical and morphological differences between the two species. Redroot pigweed was easier to control with both products than velvetleaf. Whereas 200-grain vinegar applied at 636 L/ha provided 100% control (6 d after treatment [DAT]) and mortality (9 DAT) of two-leaf redroot pigweed, this same treatment on two-leaf velvetleaf provided only 73% control and 18% mortality. The obtuse leaf blade angle in velvetleaf moved product away from the shoot tip, whereas in pigweed, the acute leaf blade angle, deep central leaf vein, and groove on the upper side of the leaf petiole facilitated product movement toward the stem axis and shoot tip. For both species, and at all application timings, 150-grain vinegar at 636 L/ha provided control equal to that of 300-grain vinegar at 318 L/ha. As growth stage advanced, control and biomass reduction decreased and survival increased. Application timing will be critical to maximizing weed control with vinegar and clove oil.

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