Unraveling Sorghum Allelopathy in Agriculture: Concepts and Implications

Allelopathy is an ecological phenomenon that involves the production and release of biomolecules from different crops, cultivated plants, and bacteria or fungi into the soil rhizosphere and impacts other organisms in the vicinity. Sorghum possesses vital allelopathic characteristics due to which it produces and releases different biomolecules from its root hairs, stems, and grains. Several studies have reported that sorghum acts as an allelopathic crop, decreasing the growth and eco-physiological attributes of surrounding plants and weeds growing simultaneously or subsequently in the field. Sorghum allelopathy has been exploited in the context of green manure, crop rotations, cover crops, and intercropping or mulching, whereas plant aqueous extracts or powder might be an alternate method of weed control. A diverse group of allelochemicals, including benzoic acid, p-hydroxybenzoic acid, vanillic acid, ferulic acid, chlorogenic acid, m-coumaric acid, p-coumaric acid, gallic acid, caffeic acid, p-hydroxibenzaldehyde, dhurrin, sorgoleone, m-hydroxybenzoic acid and protocatechuic acid, have been isolated and identified from different plant tissues of sorghum and root exudates. These allelochemicals, especially sorgoleone, have been investigated in terms of their mode(s) of action, specific activity and selectivity, release in the rhizosphere and uptake and translocation in sensitive species. The present review describes the importance of sorghum allelopathy as an ecological tool in managing weeds, highlighting the most recent advances in the allelochemicals present in sorghum, their modes of action, and their fate in the ecosystem. Further research should focus on the evaluation and selection of sorghum cultivars with high allelopathic potential, so that sorghum allelopathy can be better utilized for weed control and yield enhancement.

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Relationships Between the Content of Phenolic Compounds and the Antioxidant Activity of Polish Honey Varieties as a Tool for Botanical Discrimination

Molecules ◽

10.3390/molecules26061810 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1810

Author(s):

Monika Kędzierska-Matysek ◽

Małgorzata Stryjecka ◽

Anna Teter ◽

Piotr Skałecki ◽

Piotr Domaradzki ◽

...

Keyword(s):

Principal Component Analysis ◽

Antioxidant Activity ◽

Phenolic Compounds ◽

Caffeic Acid ◽

Principal Component ◽

Total Content ◽

Component Analysis ◽

Total Phenolic ◽

Hydroxybenzoic Acid ◽

Coumaric Acid

The study compared the content of eight phenolic acids and four flavonoids and the antioxidant activity of six Polish varietal honeys. An attempt was also made to determine the correlations between the antioxidant parameters of the honeys and their polyphenol profile using principal component analysis. Total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (ABTS) and reduction capacity (FRAP) were determined spectrophotometrically, and the phenolic compounds were determined using high-performance liquid chromatography (HPLC). The buckwheat honeys showed the strongest antioxidant activity, most likely because they had the highest concentrations of total phenols, total flavonoids, p-hydroxybenzoic acid, caffeic acid, p-coumaric acid, vanillic acid and chrysin. The principal component analysis (PCA) of the data showed significant relationships between the botanic origin of the honey, the total content of phenolic compounds and flavonoids and the antioxidant activity of the six Polish varietal honeys. The strongest, significant correlations were shown for parameters of antioxidant activity and TPC, TFC, p-hydroxybenzoic acid, caffeic acid and p-coumaric acid. Analysis of four principal components (explaining 86.9% of the total variance), as a classification tool, confirmed the distinctiveness of the Polish honeys in terms of their antioxidant activity and content of phenolic compounds.

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Establishing white clover (Trifolium repens) as a living mulch: weed control and herbicide tolerance

Weed Technology ◽

10.1017/wet.2021.45 ◽

2021 ◽

pp. 1-28

Author(s):

Nicholas T. Basinger ◽

Nicholas S. Hill

Keyword(s):

Weed Control ◽

White Clover ◽

Cover Crops ◽

Herbicide Tolerance ◽

Single Application ◽

Weed Species ◽

Living Mulch ◽

Herbicide Resistant ◽

Research And Education ◽

Weed Emergence

Abstract With the increasing focus on herbicide-resistant weeds and the lack of introduction of new modes of action, many producers have turned to annual cover crops as a tool for reducing weed populations. Recent studies have suggested that perennial cover crops such as white clover could be used as living mulch. However, white clover is slow to establish and is susceptible to competition from winter weeds. Therefore, the objective of this study was to determine clover tolerance and weed control in established stands of white clover to several herbicides. Studies were conducted in the fall and winter of 2018 to 2019 and 2019 to 2020 at the J. Phil Campbell Research and Education Center in Watkinsville, GA, and the Southeast Georgia Research and Education Center in Midville, GA. POST applications of imazethapyr, bentazon, or flumetsulam at low and high rates, or in combination with 2,4-D and 2,4-DB, were applied when clover reached 2 to 3 trifoliate stage. Six weeks after the initial POST application, a sequential application of bentazon and flumetsulam individually, and combinations of 2,4-D, 2,4-DB, and flumetsulam were applied over designated plots. Clover biomass was similar across all treatments except where it was reduced by sequential applications of 2,4-D + 2,4-DB + flumetsulam in the 2019 to 2020 season indicating that most treatments were safe for use on establishing living mulch clover. A single application of flumetsulam at the low rate or a single application of 2,4-D + 2,4-DB provided the greatest control of all weed species while minimizing clover injury when compared to the non-treated check. These herbicide options allow for control of problematic winter weeds during clover establishment, maximizing clover biomass and limiting canopy gaps that would allow for summer weed emergence.

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Spring-planted cover crops for weed control in soybean

Renewable Agriculture and Food Systems ◽

10.1017/s1742170521000107 ◽

2021 ◽

pp. 1-8

Author(s):

Katja Koehler-Cole ◽

Christopher A. Proctor ◽

Roger W. Elmore ◽

David A. Wedin

Keyword(s):

Weed Control ◽

Biomass Production ◽

Cover Crops ◽

Weed Management ◽

Block Design ◽

Weed Suppression ◽

Crop Species ◽

Cold Temperatures ◽

Weed Biomass ◽

Small Grains

Abstract Replacing tillage with cover crops (CC) for weed management in corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] systems with mechanical weed control has many soil health benefits but in the western Corn Belt, CC establishment after harvest is hampered by cold temperatures, limited labor and few compatible CC species. Spring-planted CC may be an alternative, but information is lacking on suitable CC species. Our objective was to evaluate four spring-planted CC with respect to biomass production and weed suppression, concurrent with CC growth and post-termination. Cover crop species tested were oat (Avena sativa L.), barley (Hordeum vulgare L.), brown mustard [Brassica juncea (L.) Czern.] and yellow mustard (Brassica hirta Moench). They were compared to no-CC treatments that were either tilled pre- and post-planting of soybean (no-CC tilled) or not tilled at all (no-CC weedy). CC were planted in late March to early April, terminated 52–59 days later using an undercutter, and soybean was planted within a week. The experiment had a randomized complete block design with four replications and was repeated for 3 years. Mustards and small grains produced similar amounts of biomass (1.54 Mg ha−1) but mustard biomass production was more consistent (0.85–2.72 Mg ha−1) than that of the small grains (0.35–3.81 Mg ha−1). Relative to the no-CC weedy treatment, mustards suppressed concurrent weed biomass in two out of 3 years, by 31–97%, and small grains suppressed concurrent weed biomass in only 1 year, by 98%. Six weeks after soybean planting, small grains suppressed weed biomass in one out of 3 years, by 79% relative to the no-CC weedy treatment, but mustards did not provide significant weed suppression. The no-CC tilled treatment suppressed weeds each year relative to the no-CC weedy treatment, on average 87%. The ineffective weed control by CC reduced soybean biomass by about 50% six weeks after planting. While spring-planted CC have the potential for pre-plant weed control, they do not provide adequate early season weed suppression for soybean.

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Progress towards no-till organic weed control in western Canada

Renewable Agriculture and Food Systems ◽

10.1017/s1742170511000500 ◽

2012 ◽

Vol 27 (1) ◽

pp. 60-67 ◽

Cited By ~ 31

Author(s):

Steven J. Shirtliffe ◽

Eric N. Johnson

Keyword(s):

Weed Control ◽

Faba Bean ◽

Cover Crops ◽

Green Manure ◽

Crop Residues ◽

Organic Production ◽

Field Pea ◽

Western Canada ◽

No Till ◽

Green Manure Crops

AbstractOrganic farmers in western Canada rely on tillage to control weeds and incorporate crop residues that could plug mechanical weed-control implements. However, tillage significantly increases the risk of soil erosion. For farmers seeking to reduce or eliminate tillage, potential alternatives include mowing or using a roller crimper for terminating green manure crops (cover crops) or using a minimum tillage (min-till) rotary hoe for mechanically controlling weeds. Although many researchers have studied organic crop production in western Canada, few have studied no-till organic production practices. Two studies were recently conducted in Saskatchewan to determine the efficacy of the following alternatives to tillage: mowing and roller crimping for weed control, and min-till rotary hoeing weed control in field pea (Pisum sativum L.). The first study compared mowing and roller crimping with tillage when terminating faba bean (Vicia faba L.) and field pea green manure crops. Early termination of annual green manure crops with roller crimping or mowing resulted in less weed regrowth compared with tillage. When compared with faba bean, field pea produced greater crop biomass, suppressed weeds better and had less regrowth. Wheat yields following pea were not affected by the method of termination. Thus, this first study indicated that roller crimping and mowing are viable alternatives to tillage to terminate field pea green manure crops. The second study evaluated the tolerance and efficacy of a min-till rotary harrow in no-till field pea production. The min-till rotary hoe was able to operate in no-till cereal residues and multiple passes did not affect the level of residue cover. Field pea exhibited excellent tolerance to the min-till rotary hoe. Good weed control occurred with multiple rotary hoe passes, and pea seed yield was 87% of the yield obtained in the herbicide-treated check. Therefore, this second study demonstrated that min-till rotary hoeing effectively controls many small seeded annual weeds in the presence of crop residue and thus can reduce the need for tillage in organic-cropping systems.

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Quantitative Evaluation of Allelopathic Potentials in Soils: Total Activity Approach

Weed Science ◽

10.1614/ws-d-09-00085.1 ◽

2010 ◽

Vol 58 (3) ◽

pp. 258-264 ◽

Cited By ~ 17

Author(s):

Syuntaro Hiradate ◽

Kenji Ohse ◽

Akihiro Furubayashi ◽

Yoshiharu Fujii

Keyword(s):

Cinnamic Acid ◽

Specific Activity ◽

Quantitative Estimation ◽

Alluvial Soil ◽

Total Activity ◽

Mucuna Pruriens ◽

Maximum Effect ◽

Published Data ◽

Plant Materials ◽

Allelopathic Potential

The allelopathic potential of a plant has been evaluated on the basis of two indicators: specific activity, which is the specific concentration of the allelochemical to exert a half-maximum effect on a receiver plant (EC50), and total activity in a plant, which is the ratio of the concentration of an allelochemical in the producing plant to its EC50. In the present study, a new indicator, total activity in a soil, which takes into account the effects of a soil on the allelopathy activity, is proposed because allelopathic activity is affected by the presence of soils. The total activity in a soil was calculated by multiplying the “total activity in a plant” with a “soil factor.” In this calculation, we assumed simplified cases for comparison, such that the allelopathic plant materials are evenly incorporated in the soils and the allelochemicals are released from the plant materials to the soils at a constant rate. We conducted bioassay experiments in the presence and absence of soils and cited some published data to calculate the specific activities and total activities in a plant and in a soil. The results indicated that the allelopathies of buckwheat caused by (+)-catechin, Leucaena leucocephala by L-mimosine, Xanthium occidentale by trans-cinnamic acid, and Brassica parachinensis by cis-cinnamic acid were not significant in a volcanic ash soil, an alluvial soil, and a calcareous soil, but the allelopathy of sweet vernalgrass caused by coumarin and Spiraea thunbergii by cis-cinnamoyl glucosides was highly effective in those soils. The allelopathies of Juglans species caused by juglone plus juglone precursors and Mucuna pruriens by L-DOPA would depend highly on the soil types. Although some limitations exist for this approach, the total activity approach would allow for a better quantitative estimation of the allelopathic potential of plant materials in soils.

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Herbicide-resistant crops in resistant weed management : An industrial perspective

Phytoprotection ◽

10.7202/706074ar ◽

2005 ◽

Vol 75 (4) ◽

pp. 79-84 ◽

Cited By ~ 2

Author(s):

D. Shaner

Keyword(s):

Weed Control ◽

Weed Management ◽

Wild Species ◽

Integrated Weed Management ◽

Herbicide Resistant ◽

Resistant Varieties ◽

Selection Of

Some of the first products of biotechnology to reach the marketplace have been herbicide-resistant crops. Industry sees the development of herbicide-resistant varieties as a way to increase the availability of proven herbicides for a broader range of crops. However, the development of herbicide- resistant crops requires special attention to potential environmental questions such as herbicide usage, selection of resistant weed biotypes and spread of resistance from the resistant crop to wild species. Industry is actively addressing these concerns during the process of development. Proper development and use of herbicide-resistant crops in integrated weed management programs will provide farmers with increased flexibility, efficiency, and decreased cost in their weed control practices without increasing the risk of herbicide-resistant weeds. Furthermore, herbicide-resistant crops should prove to be valuable tools in managing herbicide- resistant weeds.

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Allelopathic Potential of Lingonberry (Vaccinium vitis-idaeaL.) Litter for Weed Control

Biological Agriculture & Horticulture ◽

10.1080/01448765.2002.9754946 ◽

2002 ◽

Vol 20 (1) ◽

pp. 11-28 ◽

Cited By ~ 4

Author(s):

Meeri Saario ◽

Susanna Koivusalo ◽

Into Laakso ◽

Janne Autio

Keyword(s):

Weed Control ◽

Allelopathic Potential

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Influence of a Rye Cover Crop on the Critical Period for Weed Control in Cotton

Weed Science ◽

10.1614/ws-d-14-00075.1 ◽

2015 ◽

Vol 63 (1) ◽

pp. 346-352 ◽

Cited By ~ 22

Author(s):

Nicholas E. Korres ◽

Jason K. Norsworthy

Keyword(s):

Weed Control ◽

Cover Crops ◽

Cover Crop ◽

Critical Period ◽

Yield Loss ◽

Growing Season ◽

Weed Biomass ◽

Weed Density ◽

Presence And Absence ◽

Weed Removal

Cover crops are becoming increasingly common in cotton as a result of glyphosate-resistant Palmer amaranth; hence, a field experiment was conducted in 2009 and 2010 in Marianna, AR, with a rye cover crop used to determine its effects on the critical period for weed control in cotton. Throughout most of the growing season, weed biomass in the presence of a rye cover crop was lesser than that in the absence of a rye cover crop. In 2009, in weeks 2 through 7 after planting, weed biomass was reduced at least twofold in the presence of a rye cover compared with the absence of rye. In 2009, in both presence and absence of a rye cover crop, weed removal needed to begin before weed biomass was 150 g m−2, or approximately 4 wk after planting, to prevent yield loss > 5%. Weed density was less in 2010 than in 2009, so weed removal was not required until 7 wk after planting, at which point weed biomass values were 175 and 385 g m−2in the presence and absence of a cover crop, respectively.

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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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