Comparison of the Allelopathic Potential of Leguminous Summer Cover Crops: Cowpea, Sunn Hemp, and Velvetbean

The phytotoxicity of aqueous foliar extracts and ground dried residues of sunn hemp (Crotalaria juncea L.), cowpea [Vigna unguiculata (L.) Walp. cv. Iron Clay], and velvetbean [Mucuna deeringiana (Bort) Merr.] to crop and weed germination and growth was evaluated to compare the allelopathic potential of the cover crops. By 14 days after treatment (DAT), goosegrass [Eleusine indica (L.) Gaertn.] germination with 5% aqueous extracts of all cover crops (w/v fresh weight basis) was similar and greater than 75% of control. However, with the 10% extracts, goosegrass germination was lowest with cowpea extract, intermediate with velvetbean extract, and highest with sunn hemp extract. Livid amaranth (Amaranthus lividus L.) germination declined to ≈50% with cowpea and sunn hemp extracts and even lower to 22% with velvetbean extract. The suppression of livid amaranth germination was greater with the 10% extracts than the 5% extracts. Bell pepper (Capsicum annuum L.) germination was unaffected by velvetbean extract, inhibited more by the 5% cowpea extract than the 10% extract, and was also sensitive to the 10% sunn hemp extract. All cover crop extracts resulted in an initial delay in tomato (Lycopersicon esculentum Mill.) germination, but by 14 DAT, inhibition of germination was apparent only with cowpea extract. The phytotoxicity of ground dried residues of the three cover crops on germination, plant height, and dry weight of goosegrass, smooth amaranth (A. hybridus L.), bell pepper, and tomato was evaluated in greenhouse studies. Goosegrass germination was inhibited in a similar manner by residues of the three cover crops to 80% or less of control. Smooth amaranth germination, plant height, and dry biomass were more sensitive to sunn hemp residues than to cowpea and velvetbean residues. Bell pepper germination, plant height, and dry weight were greater than 90% of control except for dry weight with cowpea residue, which was only 78% of control. The greatest effect of cover crop residue on tomato occurred with dry weight, because dry weights with cowpea and sunn hemp were only 76% and 69% of control, respectively, and lower than with velvetbean. There was more evidence of cover crop phytotoxicity with the weed species than with the crop species and cowpea extracts and residue affected all species more consistently than those of sunn hemp and velvetbean.

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Allelopathic Influence of Germinating Seeds and Seedlings of Cover Crops on Weed Species

Weed Science ◽

10.1017/s0043174500094376 ◽

1996 ◽

Vol 44 (3) ◽

pp. 579-584 ◽

Cited By ~ 46

Author(s):

Melinda L. Hoffman ◽

Leslie A. Weston ◽

John C. Snyder ◽

Emilie E. Regnier

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Resource Competition ◽

Petri Dish ◽

Dry Weight ◽

Weed Species ◽

Allelopathic Potential ◽

Below Ground ◽

Allelopathic Interference ◽

Radicle Length

Bioassays using binary mixtures that included a cover crop with known allelopathic potential and a weed species were employed to determine the importance of allelopathy compared to resource competition as interference mechanisms. Responses of weed species germinated with cover crops in a petri dish were measured. Interference between weed and cover crop seedlings was determined in a greenhouse experiment using the additive design, which included partitions to reduce above- and below-ground competition and used capillary mat subirrigation to control moisture and fertilizer availability. Germinating sorghum reduced radicle length of weeds, whereas germinating rye tended to increase weed radicle length. Methods limited above-ground competition, so likely interference mechanisms were below-ground competition and allelopathy. Germination with a cover crop had little effect on germination and shoot length of weeds. Increased density of rye but not of sorghum reduced growth of barnyardgrass seedlings. Reduced number of barnyardgrass leaves in the presence of rye was likely due to allelopathy. Suppression of barnyardgrass dry weight attributed to allelopathic interference by rye was successfully separated and compared to the combined effects of competition and allelopathy.

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ALLELOPATHIC POTENTIAL OF WEED SPEICES AGERATUM CONYZOIDES L. AND CLEOME VISCOSA L. ON GERMINATION AND GROWTH OF SESAMUM INDICUM L

Kongunadu Research Journal ◽

10.26524/krj106 ◽

2015 ◽

Vol 2 (2) ◽

pp. 114-117

Author(s):

Anbarasan R ◽

Prabhakaran J

Keyword(s):

Growth Parameters ◽

Dry Weight ◽

Inhibitory Effect ◽

Germination Percentage ◽

Sesamum Indicum ◽

Weed Species ◽

Ageratum Conyzoides ◽

Allelopathic Potential ◽

Germination And Growth ◽

Cleome Viscosa

Various concentrations (5%, 10%, 15% and 20%) of aqueous extracts prepared from two weed species namely Ageratum conyzoides L. and Cleome viscosa L. and used for the present experiments to determine their allelopathic potential on growth and developmental changes on sesame (Sesamum indicum L.). The weed extracts showed an inhibitory effect on germination percentage, root and shoot growth, and fresh and dry weight of sesame seedlings. The extracts of A.conyzoides had more inhibitory effect at 20%concentration,than that of C.viscosa on growth parameters of sesame.

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Allelopathic potential of Artemisia herba-alba and Anthemis arvensis to control Weeds in Wheat (Triticum aestivum) and Barley (Hordeum vulgare)

South Asian Journal of Experimental Biology ◽

10.38150/sajeb.6(3).p95-100 ◽

2016 ◽

Vol 6 (3) ◽

pp. 95-100

Author(s):

Nadi Awwad Al Harbi

Keyword(s):

Triticum Aestivum ◽

Hordeum Vulgare ◽

Aqueous Extract ◽

Weed Management ◽

Allelopathic Effect ◽

Weed Species ◽

Crop Species ◽

Allelopathic Potential ◽

Anthemis Arvensis ◽

Germination And Growth

The aim of the present study was to investigate the potentials for utilization of Artemisia herba-alba and Anthemis arvensis shoot aqueous extract at different concentrations (1%, 3%, and 5%) to suppress the germination and growth of Panicum turgidum and Portulaca oleracea (weeds of crop fields) in Petri dish experiment. Results indicated that the degree of inhibition on seed germination and growth of the recipient species was largely dependent on the concentration of A. herba-alba and A.arvensis shoot aqueous extract. The aqueous extract of A.herba-alba showed the highest allelopathic effect on the germination of the seeds of P. turgidum, (10%,10% and 0%) while the effect of A. arvensis shoot aqueous extract was greater on the germination of the seeds P. oleracea (40%,0% and 0%). Percentage germination of the two selected crop species Triticum aestivum and Hordeum vulgare also de-creased as the A.herba-alba and A.arvensis shoot aqueous extract concentra-tion increased from 1% to 5% (90%,80% and 70%),(40%,40% and 20%). But the inhibition percentage was largely less than that of weed species. The results also showed that H.vulgare was more sensitive than T. aestivum and responds more strongly to the increase of concentration of A. herba-alba shoot aqueous extract . Results also showed that the radicle length of almost all tested species was more sensitive to allelochemicals from A.herba-alba and A.arvensis shoot aqueous extract than plumule length. Therefore, A. herba-alba and A. arvensis shoot aqueous extract may offer promises for their usefulness as a tool for weed management.

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MANAGEMENT OF COVER CROPS FOR WEED CONTROL BETWEEN PLASTIC MULCH IN PEPPERS (CAPSICUM ANNUUM)

HortScience ◽

10.21273/hortsci.28.4.257e ◽

1993 ◽

Vol 28 (4) ◽

pp. 257E-257

Author(s):

Francis X. Mangan ◽

Mary Jane Else ◽

Stephen J. Herbert

Keyword(s):

White Clover ◽

Cover Crops ◽

Cover Crop ◽

Lolium Multiflorum ◽

Field Research ◽

Soil Surface ◽

Winter Rye ◽

Weed Species ◽

Plastic Mulch ◽

Crop Species

Field research was conducted in Deerfield, Mass. to study the effects of different cover crop species seeded between plastic mulch on weed pressure and pepper yield. A complete fertilizer was applied before plastic was laid on Sept. 13, 1991. Two cover crop treatments were seeded Sept. 13, 1991: white clover (Trifolium repens) alone and hairy vetch (Vicia villosa) in combination with winter rye (Secale cereale). On May 27, 1992 the vetch and rye were mow-killed with the biomass left on the soil surface. Annual rye (Lolium multiflorum) was then seeded on the same day as the third cover crop treatment. The remaining two treatments were a weedy check and a hand-weeded check. Peppers were transplanted into the plastic on May 31. Both the annual rye and clover were mowed three times over the course of the experiment with the biomass left between the plastic mulch. The white clover and annual rye were much more competitive with weed species than the dead mulch of vetch and rye. The three cover crop treatments had pepper yields that were severely depressed compared to the hand-weeded treatment. Among the three cover crop treatments, only the annual rye yielded more peppers than the weedy check.

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Winter Annual Weed Suppression in Rye–Vetch Cover Crop Mixtures

Weed Technology ◽

10.1614/wt-d-12-00084.1 ◽

2012 ◽

Vol 26 (4) ◽

pp. 818-825 ◽

Cited By ~ 45

Author(s):

Zachary D. Hayden ◽

Daniel C. Brainard ◽

Ben Henshaw ◽

Mathieu Ngouajio

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Field Experiments ◽

Dry Weight ◽

Weed Suppression ◽

Weed Species ◽

Cereal Rye ◽

Winter Annual ◽

Winter Annual Weeds ◽

Annual Weeds

Winter annual weeds can interfere directly with crops and serve as alternative hosts for important pests, particularly in reduced tillage systems. Field experiments were conducted on loamy sand soils at two sites in Holt, MI, between 2008 and 2011 to evaluate the relative effects of cereal rye, hairy vetch, and rye–vetch mixture cover crops on the biomass and density of winter annual weed communities. All cover crop treatments significantly reduced total weed biomass compared with a no-cover-crop control, with suppression ranging from 71 to 91% for vetch to 95 to 98% for rye. In all trials, the density of nonmustard family broadleaf weeds was either not suppressed or suppressed equally by all cover crop treatments. In contrast, the density of mustard family weed species was suppressed more by rye and rye–vetch mixtures than by vetch. Cover crops were more consistently suppressive of weed dry weight per plant than of weed density, with rye-containing cover crops generally more suppressive than vetch. Overall, rye was most effective at suppressing winter annual weeds; however, rye–vetch mixtures can match the level of control achieved by rye, in addition to providing a potential source of fixed nitrogen for subsequent cash crops.

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Evaluation of Summer Cover Crops for Vegetable Production in South Florida

HortScience ◽

10.21273/hortsci.33.3.524e ◽

1998 ◽

Vol 33 (3) ◽

pp. 524e-524

Author(s):

Herbert Bryan ◽

Yuncong Li

Keyword(s):

Cover Crops ◽

Cover Crop ◽

Dry Weight ◽

South Florida ◽

Large Field ◽

Vegetable Production ◽

Tropical Fruits ◽

Sunn Hemp ◽

Production Practices ◽

Chemical Inputs

Cover crops are used for weed control and to retain nutrients during the heavy summer rains and have become an integral part of vegetable production practices in south Florida. Moreover the use of cover crops will continue to increase as farmers seek to improve soil quality and reduce chemical inputs. A wide variety of plants are used as cover crops in south Florida. Obviously legumes contribute more nitrogen by fixing N compared to nonlegumes such as sorghum–Sudan grass, which is a common cover crop in this area. We have evaluated 10 cover crops, and five of them are legumes. The sunn hemp, Crotalaria juncea L, stands out from other tested cover crops. Sunn hemp produced 8960 kg dry weight per ha and fixed up to 336 kg N/ha. We have strongly recommended sunn hemp as a cover crop for vegetables and tropical fruits in south Florida. A large field demonstration will be conducted in a grower's field in the summer rainy season of 1998.

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Cover-Crop Species as Distinct Biotic Filters in Weed Community Assembly

Weed Science ◽

10.1614/ws-d-14-00071.1 ◽

2015 ◽

Vol 63 (1) ◽

pp. 282-295 ◽

Cited By ~ 20

Author(s):

Richard G. Smith ◽

Lesley W. Atwood ◽

Fredric W. Pollnac ◽

Nicholas D. Warren

Keyword(s):

Cover Crops ◽

Community Assembly ◽

Cover Crop ◽

Weed Species ◽

Seeding Rate ◽

Crop Species ◽

Cover Cropping ◽

Directional Filtering ◽

Weed Communities ◽

Sorghum Sudangrass

Cover crops represent a potentially important biological filter during weed community assembly in agroecosystems. This filtering could be considered directional if different cover-crop species result in weed communities with predictably different species composition. We examined the following four questions related to the potential filtering effects of cover crops in a field experiment involving five cover crops grown in monoculture and mixture: (1) Do cover crops differ in their effect on weed community composition? (2) Is competition more intense between cover crops and weeds that are in the same family or functional group? (3) Is competition more intense across weed functional types in a cover-crop mixture compared with cover crops grown in monocultures? (4) Within a cover-crop mixture, is a higher seeding rate associated with more effective biotic filtering of the weed community? We found some evidence that cover crops differentially filtered weed communities and that at least some of these filtering effects were due to differential biomass production across cover-crop species. Monocultures of buckwheat and sorghum–sudangrass reduced the number of weed species relative to the no-cover-crop control by an average of 36 and 59% (buckwheat) and 25 and 40% (sorghum–sudangrass) in 2011 and 2012, respectively. We found little evidence that competition intensity was dependent upon the family or functional classification of the cover crop or weeds, or that cover-crop mixtures were stronger assembly filters than the most effective monocultures. Although our results do not suggest that annual cover crops exert strong directional filtering during weed community assembly, our methodological framework for detecting such effects could be applied to similar future studies that incorporate a greater number of cover-crop species and are conducted under a greater range of cover-cropping conditions.

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Allelopathic Impact of Cover Crop Species on Soybean and Goosegrass Seedling Germination and Early Growth

Agriculture ◽

10.3390/agriculture11100965 ◽

2021 ◽

Vol 11 (10) ◽

pp. 965

Author(s):

Kendall Sheldon ◽

Sam Purdom ◽

Avat Shekoofa ◽

Larry Steckel ◽

Virginia Sykes

Keyword(s):

Cover Crops ◽

Root Length ◽

Cover Crop ◽

Deionized Water ◽

Weed Suppression ◽

Crop Species ◽

Allelopathic Potential ◽

Row Crops ◽

Crimson Clover ◽

Seedling Root

Cover crops can provide a variety of benefits to an agricultural system: weed suppression, soil quality improvement, and soil water infiltration. Although there is ample research documenting weed suppression from cover crops, the mechanics of the suppression are not implicitly understood. Along with the aforementioned positive attributes, negative allelopathic effects on row crops planted into cover crop systems have been documented. The objective of this study was to evaluate the allelopathic potential of certain cover crop species on soybean (Glycine max L.) and goosegrass (Eleusine indica L.) germination and early seedling growth under controlled environments in petri dish and pot experiments. Leachates from above-ground biomass of five cover crop species, wheat (Triticum aestivum L.), cereal rye (Secale cereale), hairy vetch (Vicia villosa), crimson clover (Trifolium incarnatum L.), and canola (Brassica napus L.), from two locations (East and Middle Tennessee) were extracted and applied at 0 (water) and 50 v/v. In experiment I, both soybean and goosegrass seeds were examined, and, in experiment II, only soybean seeds were examined under the application of cover crop leachates. Most cover crop leachates from both locations significantly reduced the soybean seedling root length (p < 0.01). Overall, the application of canola extract (East Tennessee) suppressed soybean seed germination the most (28%) compared to deionized water. For goosegrass, the wheat cover crop leachate significantly reduced seedling root length (p < 0.01). In experiment II, the soybean root nodulation was significantly increased with the wheat extract treatment compared to deionized water. While the results indicate that the location and environment may change cover crop species allelopathic potential, the wheat cover crop leachate had the most potent allelopathic impact on goosegrass germination and growth; however, had the lowest observed adverse effect on our tested row crop, soybean.

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

Italian Journal of Agronomy ◽

10.4081/ija.2021.1869 ◽

2021 ◽

Cited By ~ 1

Author(s):

Lara Abou Chehade ◽

Carolina G. Puig ◽

Carlos Souto ◽

Daniele Antichi ◽

Marco Mazzoncini ◽

...

Keyword(s):

Cover Crops ◽

Secale Cereale ◽

Cover Crop ◽

Crop Residues ◽

Aqueous Extracts ◽

Inhibitory Effects ◽

Weed Species ◽

Allelopathic Potential ◽

Better Than

Cover crops are essential tools in agroecosystems 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 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 substantial effect of the mixture on C. canadensisseeds. 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. Still, the cover crop mixture mulch 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, that through slow decomposition may constitute potential natural herbicides. From the analysis of the aqueous extracts, other non-analyzed 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 in vitro bioassays. - The aqueous extracts, depending on the concentration of residues, had inhibitory effects on radicle and shoot growth of A. retroflexus, C. canadensis and D. sanguinalis. - Under field conditions, mulch of a mix of rye and squarrose clover suppressed weeds better than the single species.

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Impacts of Smooth Pigweed (Amaranthus hybridus) on Cover Crops in Southern Ontario

Agronomy ◽

10.3390/agronomy10040529 ◽

2020 ◽

Vol 10 (4) ◽

pp. 529

Author(s):

Heather VanVolkenburg ◽

Frédérique C. Guinel ◽

Liette Vasseur

Keyword(s):

Cover Crops ◽

Trifolium Pratense ◽

Lolium Multiflorum ◽

Dry Weight ◽

Root Weight ◽

Crop Species ◽

Amaranthus Hybridus ◽

Shoot Weight ◽

Noxious Weed ◽

Germination And Growth

Amaranthus hybridus is a noxious weed in Ontario, with demonstrated allelopathic properties that can lead to decreased agricultural production. We tested the germination and growth of five cover crop species exposed to A. hybridus extracts, and to dried or fresh materials in soil. A germination index was calculated, and the dry weight of plant organs were measured to quantify responses to treatments. All species had reduced germination (≤29%) in 100% extract. Trifolium pratense had significant root weight reductions in extract (52%) and dried (72%) treatments, whereas shoot weight only decreased (48%) in dried treatment. Medicago sativa shoot weight decreased (52%) in 20g fresh treatment, while root weight decreased (62%) in dried treatment. Shoot weight of Raphanus sativus increased (32%) at mid-extract concentrations, while root weight increased (33%) only with dried treatment; however, both its shoot and root weight decreased (>40%) in fresh treatment. Only the shoot weight of Lolium multiflorum increased (41% in 75% extract and 55% in dried treatment). Both Cichorium intybus shoot and root weights decreased (~50%) in fresh treatment. Crop responses to A. hybridus are complex, and material and species-dependant. Further testing in the field may provide a more comprehensive understanding of how to improve the management of A. hybridus.

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