scholarly journals Differential Response of Weeds and Vegetable Crops to Aqueous Extracts of Hairy Vetch and Cowpea

HortScience ◽  
2006 ◽  
Vol 41 (3) ◽  
pp. 695-700 ◽  
Author(s):  
Erin C. Hill ◽  
Mathieu Ngouajio ◽  
Muraleedharan G. Nair

Laboratory experiments were conducted to study the effect of aqueous extracts of hairy vetch (Vicia villosa Roth) and cowpea (Vigna unguiculata (L.) Walp) cover crops on germination and radicle elongation in seven vegetable and six weed species. Lyophilized aqueous extracts of the cover crops were dissolved in reverse osmosis (RO) water to produce seven concentrations: 0.00, 0.25, 0.50, 1.00, 2.00, 4.00, and 8.00 g·L–1. Each treatment had 4 replications and the full experiment was repeated. Experiment 1 (E1) and Experiment (E2) were conducted under similar conditions. In general, seed germination was not affected by extracts of both cover crops. However, radicle growth of all species tested (except common milkweed exposed to cowpea extract) was affected by the cover crop residue extracts. Low concentrations of hairy vetch extract stimulated the radicle growth of carrot, pepper, barnyardgrass, common milkweed, and velvetleaf. Likewise, low concentrations of cowpea extract stimulated the growth of corn, barnyardgrass, and velvetleaf. At higher concentrations all species tested were negatively affected. The order of species sensitivity to the hairy vetch extract, as determined by the IC50 (concentration required to produce 50% radicle inhibition) values, was common chickweed > redroot pigweed> barnyardgrass E1 > carrot E1 > wild carrot > corn > carrot E2 > lettuce > common milkweed > tomato > onion > barnyardgrass E2 > velvetleaf > pepper > cucumber (most sensitive to least sensitive). For cowpea the order was common chickweed > redroot pigweed > corn > tomato > lettuce > wild carrot > pepper > carrot > cucumber > onion> barnyardgrass and velvetleaf. Results suggest that the susceptibility of weeds and vegetable crops to aqueous extracts of hairy vetch and cowpea is dependent on both species and extract concentration.

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1021D-1021
Author(s):  
Erin C. Hill ◽  
Mathieu Ngouajio

Hairy vetch (Vicia villosa Roth) (HV) and cowpea [Vigna unguiculata (L.) Walp.] (CP) are two leguminous cover crops used in vegetable production systems. The residues of both species have been shown to suppress weeds via allelopathic interactions; however, they may also carry a risk of crop injury. A laboratory experiment was designed to study the dose response of carrot, sweet corn, cucumber, lettuce, onion, pepper, and tomato germination and radicle elongation to the aqueous extracts of both HV and CP. Aqueous extracts of fresh, whole plants were lyophilized to obtain a dry powder. Treatments of 0.00, 0.25, 0.50, 1.00, 2.00, 4.00, and 8.00 g dry extract/L of distilled water were applied to 10 seeds on filter paper in petri dishes. The petri dishes were then sealed and placed in the dark at 21 °C for 4 to 7 days, depending on the species germination. After the incubation period, germination rates and radicle lengths were recorded. Each treatment had 4 replications and the full experiment was executed twice. Pepper germination was reduced by increasing concentrations of HV extract; however, all other crops were not affected by HV or CP extracts. The HV extract had a significant effect on radicle elongation in carrot, corn, cucumber, lettuce, onion, and tomato. Inhibition of radical growth at 8 g·L-1 ranged from 42% in cucumber to as high as 81% in carrot. The CP extract had a negative effect on the radicle elongation of carrot, corn, lettuce, and tomato. Inhibition at 8 g·L-1 ranged from 42% in carrot to 67% in tomato. This study shows that both HV and CP extracts hold the potential to negatively affect the listed crops. Therefore, studies need to be done on the persistence of these effects in the field to maximize weed control while avoiding crop injury.


Weed Science ◽  
2018 ◽  
Vol 66 (3) ◽  
pp. 379-385 ◽  
Author(s):  
Charles L. Mohler ◽  
Alan G. Taylor ◽  
Antonio DiTommaso ◽  
Russell R. Hahn ◽  
Robin R. Bellinder

AbstractIncorporation of cover crop residue into the soil has been suggested as a means for reducing weed seedbanks. To explore this hypothesis, we buried mesh bags of seeds mixed with sand at 15-cm depth in late fall in plots that had been planted with rye (Secale cerealeL.) or hairy vetch (Vicia villosaRoth.) or left unplanted. Separate bags contained either velvetleaf (Abutilon theophrastiMedik.), giant foxtail (Setaria faberiHerrm.), Powell amaranth (Amaranthus powelliiS. Watson), or common lambsquarters (Chenopodium albumL.). The experiment used a randomized complete block design with five replications, and enough bags were buried to allow a final recovery in each of the following three springs. Each spring, bags were exhumed, and seeds were either counted and tested for viability or mixed with chopped cover crop material or simply stirred for control bags, and the material was reburied. The experiment was completed twice with initial burials in fall of 2011 and 2013. Rye had no consistent effect on persistence of seeds of any of the species. For two observation intervals, rye increased persistence of a species; for another two intervals, it decreased persistence relative to the control; but mostly rye did not affect persistence. Hairy vetch decreased persistence ofC. albumandA. powelliiin both runs of the experiment but had no effect on persistence ofA. theophrastiandS. faberi. Germination of the first two species is promoted by nitrate, whereasA. theophrastigermination is not sensitive to nitrate, andS. faberiis only rarely nitrate sensitive. We suggest that nitrate released during decomposition of hairy vetch may have promoted fatal germination ofC. albumandA. powellii. Incorporation of legume cover crops like hairy vetch may provide a means for decreasing the seedbanks of the many weed species whose germination is promoted by nitrate. The lack of any reduction ofA. theophrastiandS. faberiseed persistence in response to hairy vetch and the inconsistent and mostly negligible effect of rye indicate that a general increase in readily decomposable organic matter through incorporation of cover crops may be ineffective at reducing weed seedbanks.


2014 ◽  
Vol 47 (2) ◽  
pp. 29-40 ◽  
Author(s):  
S. Hassannejad ◽  
A.R. Mobli

Abstract In order to evaluate the effects of some cover crops on extinction coefficient and weed cover percentage in sunflower, a field experiment was conducted based on a randomized complete block design with nine treatments and three replicates at the Agricultural Research Station, Tabriz University of Iran, during growing season 2012-2013. Treatments were triticale, hairy vetch, rapeseed, triticale + hairy vetch, triticale + rapeseed, hairy vetch + rapeseed, application of trifluralin herbicide, and controls (weed infested and weed free without planting cover crop). Result indicated than once established, living mulches can rapidly occupy the open space between the rows of the main crop and use the light that would otherwise be available to weeds. In the all cover crops treatments, the light extinction coefficient was increased and weed cover percentage was reduced. Highest reduction in total weed species was observed in hairy vetch + rapeseed and triticale + rapeseed cover crop 61.92% and 61.43 %, respectively, compared to weed infested, so this treatment was better than trifluralin application. It concluded that cover crops could be considered as integrated strategies for weed sustainable management.


1996 ◽  
Vol 121 (3) ◽  
pp. 586-591 ◽  
Author(s):  
Vasey N. Mwaja ◽  
John B. Masiunas ◽  
Catherine E. Eastman

The effect of cover-crop management on growth and yield of `Bravo' cabbage (Brassica oleracea var. Capitata L.), `Market Pride' tomato (Lycopersicon esculentum Mill.), and `Mustang' snap bean (Phaseolus vulgaris L.) was determined. Each fall, `Wheeler' winter rye (Secale cereale L.) and `Oregon Crown' hairy vetch (Vicia villosa Roth) were interseeded. The following spring, the cover crops were killed by either applying glyphosate and mowing (CC-G) or mowing and disking (CC-D). Trifluralin was preplant incorporated into bare ground as a conventional tillage (CT) treatment. In 1992 and 1993, a chicken (Gallus gallus L.) based fertilizer was applied to half the subplots. The greatest snap bean and cabbage yields were in CT. The system with the greatest tomato yields varied. In 1991, the greatest tomato yields were in the CT treatment, while in 1992 yields were greatest in the CT and CC-D treatments, and in 1993 the greatest yields were in CT and CC-G. Cabbage yields were greater in the fertilized than the unfertilized treatments. In 1992, infestations of diamondback moth, imported cabbageworm, and cabbage looper were greater in CT than in the CC-G treatment. Three years of the CC-G treatment increased soil organic matter from 3.07% to 3.48% and increased soil pH from 6.30 to 6.51, while neither changed in the CT. Chemical names used: N-(phosphonomethyl) glycine (glyphosate); 2,6-dinitro-N,N-dipro`pyl-4-(trifluoromethyl) benzenamine (trifluralin).


HortScience ◽  
2002 ◽  
Vol 37 (3) ◽  
pp. 490-495
Author(s):  
Clydette M. Alsup ◽  
Brian A. Kahn ◽  
Mark E. Payton

Hairy vetch (Vicia villosa Roth) cover crops were grown in a rotation with sweet corn (Zea mays var. rugosa Bonaf.) and muskmelon (Cucumis melo L. Reticulatus group) to evaluate the legume's ability to remove excess P from soils when poultry litter was used as a fertilizer. Fertilizer treatments were: 1) litter to meet each crop's recommended preplant N requirements (1×); 2) litter at twice the recommended rate (2×); and 3) urea at the 1× rate as the control. Following the vegetable crops, hairy vetch was planted on half of each replication, while the other half was fallowed. The vetch was removed from the field in a simulated haying operation in the spring. Soil samples were taken at 0-15 cm and 15-30 cm depths at the onset of the study and after each crop to monitor plant nutrient concentrations. The vetch sometimes raised soil test N concentrations at the 0-15 cm depth. Soil test P concentrations at the 0-15 cm sampling depth in the vetch system were consistently lower numerically, but not statistically, relative to comparable plots in the fallow system. Soil test P at the 0-15 cm depth was usually increased by litter at the 2× rate relative to the urea control, regardless of cropping system. Yields of both vegetable crops were similar among all cover crop and fertilizer treatments.


HortScience ◽  
1998 ◽  
Vol 33 (7) ◽  
pp. 1163-1166 ◽  
Author(s):  
John R. Teasdale ◽  
Aref A. Abdul-Baki

Hairy vetch (Vicia villosa Roth), crimson clover (Trifolium incarnatum L.), and rye (Secale cereale L.) and mixtures of rye with hairy vetch and/or crimson clover were compared for no-tillage production of staked, fresh-market tomatoes (Lycopersicon esculentum Mill.) on raised beds. All cover crops were evaluated both with or without a postemergence application of metribuzin for weed control. Biomass of cover crop mixtures were higher than that of the hairy vetch monocrop. Cover crop nitrogen content varied little among legume monocrops and all mixtures but was lower in the rye monocrop. The C:N ratio of legume monocrops and all mixtures was <30 but that of the rye monocrop was >50, suggesting that nitrogen immobilization probably occurred only in the rye monocrop. Marketable fruit yield was similar in the legume monocrops and all mixtures but was lower in the rye monocrop when weeds were controlled by metribuzin. When no herbicide was applied, cover crop mixtures reduced weed emergence and biomass compared to the legume monocrops. Despite weed suppression by cover crop mixtures, tomatoes grown in the mixtures without herbicide yielded lower than the corresponding treatments with herbicide in 2 of 3 years. Chemical name used: [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one](metribuzin).


Author(s):  
Lara Abou Chehade ◽  
Carolina G. Puig ◽  
Carlos Souto ◽  
Daniele Antichi ◽  
Marco Mazzoncini ◽  
...  

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.


HortScience ◽  
2004 ◽  
Vol 39 (4) ◽  
pp. 832C-832
Author(s):  
Richard Smith* ◽  
Krishna Subbarao ◽  
Steve Koike ◽  
Steve Fennimore ◽  
Adelia Barber

Growers in the Salinas Valley are not able to rotate away from lettuce to other crops such as broccoli, as often as would be desirable due to economic pressures such as high land rents and lower economic returns for rotational crops. This aggravates problems with key soilborne diseases such as Sclerotinia minor, Lettuce Drop. Mustard cover crops (Brassica juncea and Sinapis alba) are short-season alternative rotational crops that are being examined in the Salinas Valley for the potential that they have to reduce soilborne disease and weeds. Mustard cover crops have been have been shown to suppress various soilborne diseases and there are also indications that they can provide limited control of some weed species. However, no studies have shown the impact of mustard cover crops under field conditions on S. minor. In 2003 we conducted preliminary studies on the incidence of S. minor and weeds following mustard cover crops in comparison with a bare control or an area cover cropped to Merced Rye (Secale cereale). There was a slight, but significant reduction of S. minor infection in one of three trials following mustard cover crops. Mustard cover crops also reduced emergence of Shepherd's Purse (Capsella bursa-pastoris) and Common Purslane (Portulaca oleracea) these studies. Mustard cover crops have distinct nitrogen cycling characteristics. They were shown to reach a peak of release of nitrogen in 30 to 50 days following incorporation into the soil. The levels of nitrogen that are released by mustard cover crops were substantial and could be useful in nitrogen fertilizer programs for subsequent vegetable crops.


HortScience ◽  
1991 ◽  
Vol 26 (7) ◽  
pp. 860-862 ◽  
Author(s):  
Wendy A. Nelson ◽  
Brian A. Kahn ◽  
B. Warren Roberts

Several prospective cover crops were sown into 1-m2 monoculture plots on 9 Mar. 1987 and 10 Mar. 1988 at Bixby, Okla., and on 14 Mar. 1988 at Lane, Okla., after sites were plowed and fitted. Densities and dry weights of cover crops and weeds were determined in late April or early May of both years. Plots also were evaluated for degree of kill by glyphosate in 1988. Fourteen cover crops were screened at Bixby in 1987. Kentucky bluegrass (Poa pratensis L.) and three fescues (Festuca rubra L., Festuca rubra L. var. commutata Gaud.-Beaup., and Festuca elatior L.) were eliminated from further consideration due to inadequate cover density and inability to suppress weeds. Screenings of the 10 remaining covers were conducted at both locations in 1988. Annual ryegrass (Lolium multiflorum L.) and three small grains [rye (Secale cereale L.), barley (Hordeum vulgare L.), and wheat (Triticum aestivum L.)] were the most promising cover crops with respect to cover density, competitiveness against weeds, and degree of kill by glyphosate. Crimson clover (Trifolium incarnatum L.) and hairy vetch (Vicia villosa Roth) were the most promising legumes, but they generally were less satisfactory than the grassy covers in all tested aspects. A single application of glyphosate was ineffective in killing hairy vetch at both locations. Chemical name used: N-(phosphonomethyl)glycine (glyphosate).


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