scholarly journals Weed infestation and factors affecting weed incidence in spring cereals in Finland - a multivariate approach

1993 ◽  
Vol 2 (6) ◽  
pp. 525-536 ◽  
Author(s):  
Jukka Salonen
Keyword(s):  
Environmental Factors ◽  
Correspondence Analysis ◽  
Dry Weight ◽  
Organic Soils ◽  
Weed Species ◽  
Data Set ◽  
Factors Affecting ◽  
Geographical Regions ◽  
Weed Flora ◽  
Weed Infestation

Weed vegetation of spring cereal fields in southern and central Finland was analyzed by ordination methods to provide a community level description of weed populations. Attention was paid particularly to the relative importance of environmental factors affecting weed incidence such as crop management, soil properties and weather conditions. A data set of 33 weed taxa from 252 fields was subjected to both indirect and direct gradient analysis. Indirect ordination was obtained with correspondence analysis (CA), and direct gradient analyses were performed with redundancy analysis (RDA) and with canonical correspondence analysis (CCA) relating environmental factors to the occurrence of weeds. Among several management factors, continuous herbicide use explained best the variation in the species composition of weed flora. Weed vegetation was also associated with soil type, moisture conditions and soil pHH2O. Ordination diagrams visualized the species-environment interactions and detected characteristic weed species for different geographical regions. In addition to ordination analyses of weed flora, the level and structure of weed infestation are described. The density of weeds averaged 170 plants m2 (median=124) and the air-dry weight of weeds 320 kg ha-1 (median=183). The average weed density was the same in different soil types, but the weed biomass was lower in clay soils than in coarse mineral and organic soils

Factors Influencing Geosmin Production by the Cyanobacterium Oscillatoria Brevis

1988 ◽  
Vol 20 (8-9) ◽  
pp. 125-131 ◽  
Author(s):  
H. Naes ◽  
H. C. Utkilen ◽  
A. F. Post
Keyword(s):  
Environmental Factors ◽  
Dry Weight ◽  
Growth Conditions ◽  
Limited Extent ◽  
Limited Growth ◽  
Pigment Synthesis ◽  
Factors Affecting ◽  
Culture Techniques ◽  
Factors Influencing ◽  
Effect Of Inhibitors

Environmental factors affecting geosmin production by Oscillatoria brevis have been investigated under laboratory conditions using continuous culture techniques. Transition from light to nutrient limited growth conditions caused a two-fold decrease in geosmin production. However, geosmin content increased relative to pigment content (chlorophyll a and carotenoids). It has been suggested that geosmin biosynthesis in O. brevis proceeds via the isoprenoid pathway as was found in actinomycetes. Accordingly, we investigated the effect of inhibitors of the intermediate stages in this synthetic pathway in order to study the regulation of geosmin production in relation to pigment synthesis. It was concluded that geosmin seemed to function as an overflow metabolite in this pathway. Due to the only modest changes in geosmin production per dry weight compared to changes in biomass levels during light- or nutrient limited growth, contamination of eutrophic fresh waters with geosmin appears to depend mainly on the species present and its biomass level and only to a limited extent on nutrient enhanced synthesis.

scholarly journals Biodiversity of weed communities in common wheat and spelt following various forecrops

2018 ◽  
Vol 71 (4) ◽  
Author(s):  
Maria Wanic ◽  
Mariola Parzonka ◽  
Dariusz Załuski
Keyword(s):  
Species Diversity ◽  
Common Wheat ◽  
Oilseed Rape ◽  
Dry Weight ◽  
Wiener Index ◽  
Weed Species ◽  
Spelt Wheat ◽  
Weed Communities ◽  
Weed Infestation ◽  
Heading Stage

Environmentally-friendly solutions are increasingly often applied in crop cultivation technologies. These include, among others, the return of old crops (e.g., spelt wheat) and crop rotation. Ensuring a proper forecrop is essential, especially in the cultivation of winter wheat, which is susceptible to infestation by weeds. However, there is only sparse information on infestation by weeds in the cultivation of winter spelt. In this study, it was assumed that this crop is invaded by weeds to a lesser extent than wheat, especially after unfavorable forecrops. The study was based on a field experiment conducted in the east part of Poland. The aim was to compare the weed infestation of common wheat and spelt wheat grown after peas, oilseed rape, and after itself. Analyses of weed infestation were conducted in 2014–2016. The weed species composition and population size were determined as well as their dry weight. The following indices were calculated: index of species richness, Simpson’s domination index, Shannon–Wiener index of species diversity, and Pielou’s index of evenness. The weed infestation of spelt wheat was higher than that of common wheat during the tillering stage. It was similar in both species during the heading stage. The lowest weed infestation in both cereals was observed on a field where peas had grown. Growing after oilseed rape and after themselves contributed to an increase in weed infestation. Biomass of weeds in a field of spelt was similar after all forecrops, unlike that in wheat, where more biomass was observed after oilseed rape and wheat. A greater share of <em>Apera spica-venti</em> and <em>Viola arvensis</em> was observed in common wheat and spelt grown after oilseed rape and after themselves. Weed communities in spelt were more diverse than in wheat. The forecrops did not differentiate the species diversity in either crop.

scholarly journals Sinapis alba L. weed infestation depending on the seeding rate and N fertilizer dose in the steppe Crimea

2020 ◽  
Author(s):  
Ye.N. Rostova ◽  
Keyword(s):  
Crop Yields ◽  
Dry Weight ◽  
Weather Conditions ◽  
Sinapis Alba ◽  
Mineral Fertilizers ◽  
White Mustard ◽  
Weed Species ◽  
Seeding Rate ◽  
Sinapis Alba L ◽  
Weed Infestation

Dense white mustard (Sinapis alba L.) can suppress weeds, however excessive density negatively influences crop yields. The search for the optimal parameters for applying mineral fertilizers and the consumption of seed material will increase the crop yield and will improve its competitive ability. This work aimed to identify the seeding rate and doses of nitrogen fertilization at which white mustard plants can actively suppress weeds without reducing the productivity of the crop. In the course of this research, we established that S. alba sown at a rate of 2, 2.5 and 3 million seeds per ha suppressed the growth and development of weeds as much as possible. On average, in 2017-2019, the dry weight of weeds in the aforementioned variants was the least and reached 57.9; 42.3 and 38.4 g/m2, respectively. Weed species composition and quantitative parameters of weed infestation depended on the weather conditions of the year. The application of nitrogen fertilizer did not affect significantly the weediness of S. alba crops. The optimal density white mustard plant formed at a seeding rate of 2 million units/ha and, on average, for three years of research, the seed yield in this variant was the highest (0.6 t/ha).

scholarly journals The effect of tillage system and herbicide application on weed infestation of crops of winter spelt wheat (Triticum aestivum ssp. spelta L.) cultivars

2014 ◽  
Vol 66 (4) ◽  
pp. 173-184
Author(s):  
Sylwia Andruszczak ◽  
Piotr Kraska ◽  
Ewa Kwiecińska-Poppe ◽  
Edward Pałys
Keyword(s):  
Plant Protection ◽  
Crop Protection ◽  
Dry Weight ◽  
Control Treatment ◽  
Weed Species ◽  
Spelt Wheat ◽  
Galium Aparine ◽  
Previous Crop ◽  
Tillage System ◽  
Weed Infestation

<p>Based on a 3-year field experiment conducted on medium heavy mixed rendzina soil, the present study evaluated the effect of chemical plant protection on the species composition, number and air-dry weight of weeds infesting crops of winter spelt wheat cultivars (‘Frankenkorn’, ‘Badengold’, ‘Schwaben- speltz’, and ‘Oberkulmer Rotkorn’) sown under ploughing and ploughless tillage systems. Ploughing tillage involved skim- ming done after harvest of the previous crop and pre-sowing ploughing, while in the ploughless tillage system ploughing was replaced with cultivating. Chemical weed control included the application of the herbicides Mustang 306 SE and Attribut 70 WG. Plots where the herbicides were not used were the control treatment. On average, from 21 to 30 weed species colonised the winter spelt wheat crops compared. <em>Galium aparine </em>and <em>Apera spica-venti </em>occurred in greatest numbers and their percentage in the total number of weeds was estimated at 26–35% and 17–25%, respectively. The cultivar ‘Frankenkorn’ was the least weed-infested. Both the number of weeds in the crop of this cultivar and their above-ground dry weight were lower compared to the other cultivars. The use of reduced tillage significantly increased the air-dry weight of weeds compared to ploughing tillage. Nevertheless, it should be indicated under ploughless tillage conditions the application of chemical crop protection reduced weed biomass by 59% compared to the control treatments without crop protection.</p>

DISTRIBUTION PATTERN OF WEEDS IN WHEAT CROP GROWN IN DISTRICT KHANEWAL, PUNJAB, PAKISTAN

2020 ◽  
Vol 27 (2) ◽  
pp. 47-59 ◽  
Author(s):  
Muhammad Usman ◽  
Ghulam Murtaza ◽  
Allah Ditta ◽  
Tamana Bakht ◽  
Muhammad Asif ◽  
...  
Keyword(s):  
Distribution Pattern ◽  
Growth And Yield ◽  
Survey Study ◽  
Cereal Crops ◽  
Wheat Crop ◽  
Weed Species ◽  
Importance Value Index ◽  
Importance Value ◽  
Factors Affecting ◽  
Weed Infestation

Weed infestation is among the main biotic factors affecting growth and yield of various crops. This issue is more drastic for cereal crops like wheat which is the staple food crop of over 2.5 billion population of the world. One the control strategy is the investigated the distribution pattern of weeds under field conditions. In this regard, a survey study was conducted to investigate the distribution pattern of weed species in wheat crop during 2016-18 in district Khanewal, Punjab Pakistan. Thirty-six weed species distributed among fifteen different families collected from the study area. Family Poaceae was dominant with 10 species while family Asteraceae was the second most dominant family with four weed species. Cynadon dactylon was the most frequently found specie with frequency value 79.1% while Paspalum distichum had the highest importance value index (6.96) among the weeds of the study area.

scholarly journals Effect of Fertilization and Weed Management on Weed Flora of Hemp Crop

2020 ◽  
Vol 77 (2) ◽  
pp. 44
Author(s):  
Angeliki KOUSTA ◽  
Panayiota PAPASTYLIANOU ◽  
Nikolina CΗΕΙΜΟΝΑ ◽  
Ilias TRAVLOS ◽  
Ioanna KAKABOUKI ◽  
...  
Keyword(s):  
Weed Management ◽  
Plant Traits ◽  
Growth Parameters ◽  
Initial Growth ◽  
Weed Species ◽  
Potential Yield ◽  
Affected Plant ◽  
Weed Flora ◽  
Weed Infestation ◽  
Density And Biomass

Hemp is known to have a competitive advantage over weeds. Despite its suppressive ability, weed infestation remains an important issue during the early growth of the crop. The aim of this study was to determine the effect of fertilization and weed management on weed flora and hemp growth parameters during initial growth in the 2019 season. The experiment was laid out in a split-split plot design with three replicates: three hemp cultivars as main plots, three fertilization treatments as sub-plots and two sub-sub-plots (weedy, weed free). For the computation of height and biomass weight, 10 plants were randomly selected in each plot. Weed species were collected by quadrate and density and biomass weight were determined. ANOVA revealed that all factors and their interactions significantly affected plant traits. Hemp cultivars showed different competitive ability. ‘Futura 17’ reduced weed measurement traits better than ‘Uso 31’. Density and biomass of nitrophilous weeds increased with the higher N dose compared to control (up to 56% and 79% respectively), therefore negatively affecting the growth of the hemp plants. Further research is needed in order to identify useful information on interactions between weeds and hemp crop to address potential yield losses under different weed management systems.

Effects of environmental factors on weed species composition of cereal and stubble fields in western Hungary

2010 ◽  
Vol 5 (2) ◽  
pp. 283-292 ◽  
Author(s):  
Gyula Pinke ◽  
Robert Pál ◽  
Zoltán Botta-Dukát
Keyword(s):  
Environmental Factors ◽  
Species Composition ◽  
Soil Ph ◽  
Vegetation Period ◽  
Mean Annual Precipitation ◽  
Mean Annual Temperature ◽  
Weed Species ◽  
Factors Affecting ◽  
Weed Communities ◽  
Winter Annuals

AbstractMultivariate analysis of data obtained from 184 cereal and stubble fields in low-input agricultural systems located in western Hungary was undertaken in order to asses environmental factors affecting weed species composition. For each variable, the gross and net effect on weed species composition was calculated. All variables considered in this study had a significant effect on weed species composition and explained 26.99% of the total variation. Most variation in species composition was explained by the aspect (cereal vs. stubble), followed by soil pH, mean annual precipitation, soil texture, mean annual temperature, and altitude. Separating the cereals and stubbles soil pH became the most important factor. Our results suggest that during the long vegetation period, cereal weed communities dominated by winter annuals are replaced by stubble-field weed communities dominated by summer annuals. This seasonal change may also have the same important effect on weed species composition as crop types.

scholarly journals Effects of long-term reduced tillage on weed infestation of pea (Pisum sativum L.)

2014 ◽  
Vol 67 (3) ◽  
pp. 119-126
Author(s):  
Andrzej Woźniak ◽  
Myroslawa Soroka
Keyword(s):  
Pisum Sativum ◽  
Dry Weight ◽  
Development Stage ◽  
Conventional System ◽  
Weed Species ◽  
Leaf Stage ◽  
The Third ◽  
Pod Development ◽  
Weed Infestation ◽  
Pod Development Stage

The study evaluated weed infestation of pea (<em>Pisum sativum</em> L.) cultivated under conditions of conventional (CT), reduced (RT) and herbicide tillage (HT). It demonstrated the highest weed density per m<sup>2 </sup>in plots with the herbicide (HT) and reduced (RT) systems and significantly lower weed infestation in plots cultivated in the conventional system (CT). In addition, more weeds occurred at the third leaf stage (13/14 in BBCH scale) than at the pod development stage (73/74 BBCH) of pea. The highest biomass was produced by weeds in the herbicide system (HT), a lower one – in the reduced system (RT), and the lowest one – in the conventional system (CT). The air-dry weight of weeds depended also on pea development stage. At the pod development stage (73/74 BBCH), the air-dry weight of weeds was significantly higher than at the third leaf stage (13/14 BBCH). The tillage system was also observed to influence the species composition of weeds. This trait was also affected by the period of weed infestation assessment. At the third leaf stage of pea (13/14 BBCH), there occurred 26 weed species, including 24 annual ones. The most abundant species included: <em>Chenopodium album</em> L., <em>Stellaria media</em> (L.) Vill., <em>Capsella bursa-pastoris</em> (L.) Med., <em>Matricaria inodora</em> L., <em>Thlaspi arvense</em> L., and <em>Fallopia convolvulus</em> (L.) A. Löve. At the pod development stage (73/74 BBCH), the pea crop was colonized by 24 weed species, including 3 perennial ones. At this stage the predominant species included: <em>Avena fatua</em> L., <em>Amaranthus retroflexus</em> L., <em>Papaver rhoeas</em> L., <em>Echinochloa crus-galli</em> (L.) P.B., <em>Matricaria inodora</em> L., and <em>Galeopsis tetrahit</em> L.

scholarly journals Weed infestation monitoring in vineyards in the South Sakar region of Bulgaria

2021 ◽  
Vol 13 (31) ◽  
pp. 10-16
Author(s):  
Iliyan Zheliazkov ◽  
◽  
Vyara Doycheva ◽  
Tsvetelina Ivanova ◽  
◽  
...  
Keyword(s):  
Species Composition ◽  
Climatic Region ◽  
The South ◽  
Weed Species ◽  
Weed Flora ◽  
Weed Infestation

The weed infestation monitoring was conducted in 2019 and 2020. The purpose was to document the weed flora in a large part of the wine vineyard plots in the cadastral area of the Kolarovo, Ovcharovo, Dositeevo, Balgarin and Izvorovo villages within the administrative territory of the Harmanli municipality and the micro-climatic region of South Sakar. The established weed species composition was represented by 38 weed species belonging to 18 botanical families in ratio 81.58% to 18.42% monocarpous to polycarpous species classified in a total of nine biological groups.

Some nutritional and environmental factors affecting growth and production of sclerotia by a strain of Aspergillus niger

1969 ◽  
Vol 15 (8) ◽  
pp. 835-840 ◽  
Author(s):  
V. P. Agnihotri
Keyword(s):  
Aspergillus Niger ◽  
Environmental Factors ◽  
Synergistic Effect ◽  
Magnesium Sulfate ◽  
Sodium Sulfite ◽  
Agar Medium ◽  
Carbon Sources ◽  
Dry Weight ◽  
Factors Affecting ◽  
Nutritional Elements

The effects of two nutritional elements (carbon and sulfur) and two environmental factors (pH and temperature) on growth and sclerotial production of Aspergillus niger were determined on a synthetic agar medium. The fungus grew and produced sclerotia under laboratory conditions on media containing wide ranges of carbon and sulfur sources. Of the 20 carbohydrates tested, only ribose, mannitol, and malonic, fumaric, and citric acids failed to induce production of sclerotia. A synergistic effect was observed on the formation of sclerotia when favorable and unfavorable carbon sources were supplied in different combinations. Of the 14 sulfur compounds tested, magnesium sulfate yielded the highest and sodium sulfite the lowest number of sclerotia. Raising the concentration of magnesium sulfate to 3 g/l increased the number of sclerotium initials and the number and dry weight of those which matured. In general, no correlation occurred between the number of sclerotia formed and their dry weights on different carbon or sulfur sources. Sclerotia were most numerous at pH 7.0 and 35 °C.

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