The Effect of Reduced Light Intensity on Grass Weeds

Yasin, Muhammad; Rosenqvist, Eva; Andreasen, Christian

doi:10.1017/wsc.2017.17

Cited by 15 publications

(13 citation statements)

References 33 publications

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“…Plants are able to amend their morphology and physiology to a specific set of light conditions (Delagrange et al ., ). Plants may reduce canopy branching and increase specific leaf area, petioles and internodes in response to reduced light (Callaway et al ., ; Yasin et al ., ). For example, Via et al .…”

Section: Introductionmentioning

confidence: 97%

The importance of reduced light intensity on the growth and development of six weed species

et al. 2019

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Crops limit light for photosynthesis and growth of weeds. We studied the effect of reduced light on performance of six weed species [one invasive species (Amsinckia micrantha), three common species (Veronica persica, Capsella bursa-pastoris, Viola arvensis) and two less common weeds (Anagallis arvensis and Scleranthus annuus)]. In two glasshouse experiments, six light levels were achieved aiming at 0%, 20%, 50%, 80%, 90% and 95% reduction of light and corresponding with daily light integrals (DLI) of 12.4, 9.63, 7.13, 2.74, 0.95 and 0.69 mol m À2 day À1 in experiment 1 and 21.2, 18.0, 10.7, 3.71, 1.64 and 1.20 mol m À2 day À1 in experiment 2. The number of leaves was strictly controlled by DLI. Chlorophyll content index, maximum photochemical efficiency of photosystem II (F v /F m ), stomatal conductance, flowering and dry matter were strongly reduced when DLI was reduced to 0.69-3.71 mol m À2 day À1 for all species. Threshold DLI for flowering was ca. 3.71 mol m À2 day À1 for S. annuus, V. arvensis, A. arvensis and V. persica, while C. bursa-pastoris deviated by flowering at DLI of 0.95 mol m À2 day À1 . This may explain why C. bursa-pastoris is common in the seedbank of Danish arable soils in spite of intensive farming with wellfertilised and dense crops.

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Section: Introductionmentioning

confidence: 97%

The importance of reduced light intensity on the growth and development of six weed species

et al. 2019

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“…], and their seeds may be placed below the header and escape the combine harvester. However, in a dense, well-fertilized crop, light competition results in longer internodes and higher plants improving the condition for weed seed harvesting [42].…”

Section: Discussionmentioning

confidence: 99%

Killing Weed Seeds with Exhaust Gas from a Combine Harvester

Jakobsen¹,

Jensen²,

Bitarafan³

et al. 2019

Agronomy

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We investigated if hot exhaust gas from a combine harvester could be used to reduce germination or kill weed seeds during the harvesting process. During the threshing and cleaning process in the combine, weed seeds and chaff are separated from the crop grains. After this separation, weed and crop seeds not collected can be exposed to exhaust gas before seeds are returned to the field. Seeds of some common weed species (Alopecurus myosuroides, Centaurea cyanus, Geranium pusillum, Lapsana communis, Lolium perenne, Rumex crispus, Spergula arvensis, and Tripleurospermum inodorum) were treated with exhaust gas at temperatures of 75 °C or 85 °C, 110 °C, and 140 °C for 2, 4, and 6 s, respectively. Afterwards, the seeds were germinated for 16 days. We found that 75 °C and 85 °C were insufficient to significantly reduce germination of the seeds after three durations. Some seeds were still able to germinate after 4 s exposure of 110 °C. An exposure of 140 °C for 4 and 6 s repressed germination of all species. We conclude that there is potential to develop combine harvesters that exploit the exhaust gas to either kill or reduce the ability of weed seeds to germinate before seeds are returned to the field.

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“…), and escape the header of the combine harvester, and most of the seeds may already be shed at harvest time. In high yielding production systems, like in Northern Europe, light competition in a dense crop often results in higher weed plants with longer internodes [24]. This reduces the risk that the weeds escape the header of the combine harvester.…”

Section: Discussionmentioning

confidence: 99%

Exploiting Waste Heat from Combine Harvesters to Damage Harvested Weed Seeds and Reduce Weed Infestation

et al. 2018

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Weeds are mainly controlled with herbicides in intensive crop production, but this has resulted in increasing problems with herbicide-resistant weeds and public concerns about the unwanted side-effects of herbicide use. Therefore, there is a need for new alternative methods to reduce weed problems. One way to reduce weed infestation could be to collect or kill weed seeds produced in the growing season. Crop and weeds are harvested simultaneously with the combine harvester, but most of the weed seeds are returned with the chaff to the field creating new problems in future growing seasons. During the harvesting process, the harvester produces heat. Under normal harvest conditions, the exhaust gas temperature measured directly behind the turbocharger of the engine of a combine harvester may reach between 400 • C and 480 • C depending of the size of the engine. These high temperatures indicate that there is a potential for developing a system which perhaps could be utilized to kill or damage the weeds seeds. We investigate how much heat is needed to damage weed seeds significantly and focuses on the germination patterns over time in response to these treatments. We investigated if heat treatment of weed seeds could kill the seeds or reduce seed vigour or kill the seeds before they are returned to the field. The aim is to avoid harvested viable weed seeds being added to the soil seed bank. During the threshing and cleaning process in the combine harvester, most weed seeds and chaff are separated from the crop grains. After this separation, we imagine that the weed seeds could be exposed to a high temperature before they are returned to the field. Seeds of nine common weed species were treated with temperatures of 50 • C, 100 • C, 150 • C, 200 • C, and 250 • C for 0, 2, 5, 10, and 20 s, respectively. Afterwards, the seeds were germinated for fourteen days. Seeds were differently affected by the heat treatments. We found that 50 • C and 100 • C was insufficient to harm the seeds of all species significantly at all durations. Heating with a temperature of 50 • C and 100 • C showed a slight tendency to break the dormancy of Alopecurus myosuroides Huds. and Papaver rhoeas L., but the results were not statistically significant. Seeds treated with 150 • C gave varying results depending on the duration and the weed species. The germination of A. myosuroides was significantly repressed when seeds were exposed to 250 • C for 5 s. Most species were significantly damaged when they were exposed to 250 • C for more than 10 s. Our results showed that there is a potential to explore how the waste heat energy produced by combine harvesters can be exploited to either kill or reduce the vigour of weed seeds before they are returned to the field with the chaff.

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The Effect of Reduced Light Intensity on Grass Weeds

Cited by 15 publications

References 33 publications

The importance of reduced light intensity on the growth and development of six weed species

The importance of reduced light intensity on the growth and development of six weed species

Killing Weed Seeds with Exhaust Gas from a Combine Harvester

Exploiting Waste Heat from Combine Harvesters to Damage Harvested Weed Seeds and Reduce Weed Infestation

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