Experimental Methods for Crop–Weed Competition Studies

Swanton, Clarence J.; Nkoa, Roger; Blackshaw, Robert E.

doi:10.1614/ws-d-13-00062.1

Cited by 167 publications

(137 citation statements)

References 47 publications

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“…Under field conditions, weeds compete with the target crop for resources necessary for growth and development, and subsequently reduce crop yield (Swanton et al, 2015). Under field conditions, weeds compete with the target crop for resources necessary for growth and development, and subsequently reduce crop yield (Swanton et al, 2015).…”

Section: Weed Biomassmentioning

confidence: 99%

Agronomic Responses of Brassica carinata to Herbicide, Seeding Rate, and Nitrogen on the Northern Great Plains

et al. 2018

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Brassica carinata A. Braun seeds contain high erucic and linolenic acids that are desirable for biofuel and biopolymer products. However, key agronomic practices to maximize carinata productivity on the Northern Great Plains are not well known. Here, we investigated the response of seed yield and quality to three key agronomic factors—herbicide, seeding rate, and N. The factorial experiment, conducted in nine environments (site‐years) on the Canadian prairies from 2014 to 2016, included two weed control options (weedy vs. weed‐controlled), three levels of N application (low = 32–97 kg N ha−1, medium = 75–198 kg N ha−1, and high = 117–297 kg N ha−1), and five seeding rates (50, 100, 150, 200, and 300 seeds m−2). On average, weed biomass with the herbicide‐applied treatment was 245 kg dry matter ha−1, significantly lower than the 1338 kg dry matter ha−1 with the non‐herbicide treatment, leading to 37% greater seed yield. In four of the nine environments, medium and high N fertilizer rates increased seed yield by 29 and 45%, respectively, compared with the low‐N treatment, but N fertilizer did not affect yield in the remaining five environments. Increasing seeding rates decreased weed biomass and increased seed yield. Seed oil and protein contents ranged from 37.2 to 48.5% and 22.6 to 36.3%, respectively, and these two traits had an inverse linear relationship. These results demonstrate that carinata may be well adapted to the Northern Great Plains as an alternative oilseed crop, and that seed yield and quality responses to key agronomic factors can vary with environmental conditions.

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Section: Weed Biomassmentioning

confidence: 99%

Agronomic Responses of Brassica carinata to Herbicide, Seeding Rate, and Nitrogen on the Northern Great Plains

et al. 2018

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“…Nitrogen (N) is one of the most important agricultural inputs that influences the crop-weed interference (Swanton et al 2015). Previous studies on the effect of N rate on crop-weed competition have shown variable outcomes.…”

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confidence: 99%

Influence of Nitrogen Rate, Seeding Rate, and Weed Removal Timing on Weed Interference in Barley and Effect of Nitrogen on Weed Response to Herbicides

Kumar

Jha

2016

Weed Sci

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Field experiments were conducted at the Montana State University Southern Agricultural Research Center, Huntley, MT, in 2011 through 2013 to determine the effect of nitrogen (N) rate, seeding rate, and weed removal timing on weed interference in barley. A delay in weed removal timing from the 3-to 4-leaf (LF) stage to the 8-to 10-LF stage of barley resulted in up to 3.5-fold increase in total weed biomass and 10% reduction in barley biomass, and this was unaffected by a N rate that ranged from 56 (low) to 168 (high) kg ha −1 . The effect of N rate on barley biomass was more pronounced when weed removal was delayed from the 3-to 4-LF stage to the 8-to 10-LF stage of barley and in nontreated plots. Increasing the barley seeding rate from 38 to 152 kg ha −1 increased the barley plant density by 50%, biomass by 13%, and grain yield by 29%, averaged over N rates and weed removal timing. On the basis of 5 and 10% levels of acceptable yield loss, the addition of ≥112 kg N ha −1 delayed the critical timing of weed removal by at least 1.3 wk in barley, compared with the 56 kg N ha −1 rate. A medium or high N rate prevented reduction in barley grain quality (plumpness and test weight) observed when the seeding rate was increased from 38 to 76 or 152 kg ha −1 at the low N rate. In a separate greenhouse study, the effect of N rate on the effectiveness of various herbicides for controlling wild oat, green foxtail, kochia, or Russian thistle was investigated. Results highlighted that wild oat or green foxtail grown under 56 kg N ha −1 (low N) soil required 1.4 to 2.6 times higher doses of clodinafop, fenoxaprop, flucarbazone, glyphosate, glufosinate, pinoxaden, or tralkoxydim for 50% reduction in shoot dry weights (GR 50 ) compared with plants grown under 168 kg N ha −1 (high N). Similarly, a reduced efficacy of thifensulfuron methyl + tribenuron methyl, metsulfuron methyl, or bromoxynil + pyrasulfotole was observed (evident from the GR 50 values) for kochia or Russian thistle grown under low-vs. high-N soil. Information gained from this research will aid in developing cost-effective, integrated weed management (IWM) strategies in cereals and in educating growers on the importance of fertilizer N management as a component of IWM programs. Nomenclature: Bromoxynil + pyrasulfotole; clodinafop; fenoxaprop; flucarbazone; glyphosate; glufosinate; metsulfuron methyl; pinoxaden; thifensulfuron methyl + tribenuron methyl; tralkoxydim; green foxtail; Setaria viridis (L.) Beauv.; kochia, Kochia scoparia (L.) Schrad; Russian thistle, Salsola tragus L.; barley, Hordeum vulgare L.; wild oat, Avena fatua L.

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“…An additive design (Swanton et al, 2013) was utilized for this experiment, where hybrid or shattercane densities varied while that of sorghum remained constant. The treatment design was a factorial with two weedy genotypes, shattercane and hybrid, with the hybrid being either exposed or not exposed to a herbicide application (total of three treatment levels), and five www.ccsenet.org/jas Journal of Agricultural Science Vol.…”

Section: Greenhouse Experiments and Data Collectionmentioning

confidence: 99%

“…than wheat (Triticum aestivum L.). Additive designs, where crop density is held constant while weed density varies (Swanton, Nkoa, & Blackshaw, 2013), have been widely used in field and greenhouse studies looking at yield loss-weed density relationships because they accurately reflect the reality that weeds occur within a crop planted at constant density.…”

Section: Introductionmentioning

confidence: 99%

Shattercane X ALS-Tolerant Sorghum F1 Hybrid and Shattercane Interference in ALS-Tolerant Sorghum

Werle¹,

Schmidt²,

Laborde³

et al. 2014

JAS

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ALS-tolerant grain sorghum cultivars are expected to be available for farmers within the next few years. Knowing that: i) crosses between sorghum and shattercane are likely to occur resulting in crop-to-weed gene flow; ii) ALS-susceptible shattercane X ALS-tolerant grain sorghum F1 hybrids (hybrids) were ultimately resistant to ALS-herbicides under field conditions; and iii) hybrid fitness is equal to, or greater than, the wild parent, we conducted a greenhouse study to compare the competitive effect of shattercane and hybrid on sorghum, and whether or not herbicide application would influence the competitive ability of the hybrid plants. An additive design was used where weed densities varied while that of crop remained constant. The treatment design was a factorial with two weedy genotypes, shattercane and hybrid, with the hybrid being either exposed or not exposed to an ALS-herbicide application (nicosulfuron (26.25 g ai ha -1 ) + rimsulfuron (13.16 g ai ha -1 )), and five weed densities (0, 1, 2, 3, and 4 plants pot -1 ). Sorghum density was kept at 1 plant pot -1 . F-tests were performed to compare differences across treatment levels. Shattercane and hybrid produced similar amounts of total above ground biomass within each density, and herbicide exposure did not decrease hybrid biomass production. Moreover, shattercane and hybrid competed similarly with sorghum, and a herbicide application did not reduce the competitive ability of the hybrid. Sorghum wild relatives must be managed by alternative methods before and during the adoption of ALS-tolerant sorghum technology to avoid gene flow and crop yield loss due to competition.

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Experimental Methods for Crop–Weed Competition Studies

Cited by 167 publications

References 47 publications

Agronomic Responses of Brassica carinata to Herbicide, Seeding Rate, and Nitrogen on the Northern Great Plains

Agronomic Responses of Brassica carinata to Herbicide, Seeding Rate, and Nitrogen on the Northern Great Plains

Influence of Nitrogen Rate, Seeding Rate, and Weed Removal Timing on Weed Interference in Barley and Effect of Nitrogen on Weed Response to Herbicides

Shattercane X ALS-Tolerant Sorghum F1 Hybrid and Shattercane Interference in ALS-Tolerant Sorghum

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