Mechanical and chemical weeding effects on the weed structure in durum wheat

A three-year field experiment was performed to study weed infestation of durum wheat at the stage of emergence and full maturity. Two weeding systems (WS) were used in the post-harvest period: i) mechanical weeding (MW); and ii) chemical weeding (CW). In the MW system, soil underwent shallow ploughing at a depth of 10-12 cm and double harrowing (after ploughing and 3 weeks later), whereas glyphosate only was used in the CW system. In the springtime, in both MW and CW systems, a tillage set consisting in a cultivator, a string roller and harrowing was used. Overall, the number of weeds m2, the number of weed species and the value of weed diversity indices were always higher in MW than in the CW systems in each study year at both the emergence and full maturity stage of durum wheat. The study demonstrated that at the stage of durum wheat emergence, more weeds per m2 occurred in the MW than in the CW system in each study year. Moreover, the MW systems was characterized by a higher number of weed species as well as by a higher value of weed diversity index compared to the CW system.

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Weed infestations in soybean grown in succession to cropping systems with sorghum and cover plants

Pesquisa Agropecuária Brasileira ◽

10.1590/s1678-3921.pab2020.v55.01640 ◽

2020 ◽

Vol 55 ◽

Author(s):

Joilson Sodré Filho ◽

Ricardo Carmona ◽

Robélio Leandro Marchão ◽

Arminda Moreira de Carvalho

Keyword(s):

Cover Crops ◽

Dry Matter ◽

Cropping Systems ◽

Block Design ◽

Weed Species ◽

Importance Value ◽

Randomized Complete Block Design ◽

Weed Diversity ◽

Weed Infestation ◽

Urochloa Brizantha

Abstract: The objective of this work was to evaluate the influence of sorghum and cover plant cropping systems before soybean cultivation on the occurrence of weeds during soybean growing in the Brazilian Cerrado. The experiment was carried out in a randomized complete block design, with four replicates. The treatments comprised six cropping systems before soybean: sorghum (Sorghum bicolor), palisade grass (Urochloa brizantha), and Congo grass (Urochloa ruziziensis) as cover plants, alone or intercropped, in addition to fallowing. Weeds were evaluated as to: density, dry matter mass, diversity, importance value, and similarity. The greatest similarity of weeds ocurred in single crops of sorghum, palisade grass, and Congo grass, in comparison with their intercroppings. Congo grass before soybean promoted a greater reduction in weed diversity overtime, when compared with palisade grass. The absence of cover crops before soybean cultivation increased weed infestation during the soybean cycle. The cropping systems with sorghum intercropped with cover crops before the soybean cultivation affect the diversity and the importance value of weed species.

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Abundance and Diversity Index of Weeds in Oil Palm and Vegetable Intercropping in Rainforest Zone of Nigeria

Caraka Tani Journal of Sustainable Agriculture ◽

10.20961/carakatani.v36i2.48098 ◽

2021 ◽

Vol 36 (2) ◽

pp. 227

Author(s):

Ayodele Samuel Oluwatobi ◽

Kehinde Stephen Olorunmaiye

Keyword(s):

Oil Palm ◽

Growth Habit ◽

Diversity Index ◽

Weed Species ◽

Immature Oil ◽

Weed Infestation ◽

Ondo State ◽

Abundance And Diversity ◽

Early Phases ◽

Rainforest Zone

The problem of severe weed infestation often arises during the early phases of establishment of oil palm field due to the spacing requirement and growth habit of young oil palm plantation until later years when the canopy closes. This study was conducted at Ala, Akure-North Local Government Area, Ondo State, Nigeria, to investigate the composition of weed species and their distribution in fruit vegetable-juvenile oil palm intercrop. The fallow alleys within the immature oil palm were intercropped with 2 accessions of tomato (NGB 01665 and NG/AA/SEP/09/053) and eggplant (NGB 01737). The sampling of the weed species was carried out with a quadrat (0.25 m2). Weed species parameters and the Diversity Index (D) were quantitatively analyzed. The results revealed that members of Asteraceae and Poaceae gave the highest weed species at 3 and 6 weeks after intercropping (WAI) (17.857% and 19.04%) respectively. A total of 23 and 16 were found at 3 and 6 WAI, while the least diversity index of 0.734 was recorded in the immature oil palm/tomato (NGB 01665) plot at 6 WAI. Farmers should be persuaded to simultaneously intercrop fruit vegetables within the alley of juvenile oil palm, particularly at the earlier years prior to closure of the oil palm canopy.

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Nutrient Uptake by Weeds in a Long-term Maize Field Experiment

Agrokémia és Talajtan ◽

10.1556/agrokem.55.2006.1.19 ◽

2006 ◽

Vol 55 (1) ◽

pp. 175-182 ◽

Cited By ~ 5

Author(s):

Éva Lehoczky ◽

Z. Tóth ◽

A. Kismányoky ◽

T. Kismányoky

Keyword(s):

Field Experiment ◽

Nutrient Uptake ◽

Biomass Production ◽

Development Stage ◽

Mineral Fertilizers ◽

Continuous Cropping ◽

Weed Species ◽

Weed Infestation ◽

Fertilizer Rates

The effect of four NPK fertilizer rates (NPK[1:1:1]: 0, 300, 600, 900 kg active ingredients·ha -1 ) was studied on the growth of maize and on weed infestation - bio-mass production and nutrient uptake of weeds - in four replications in a 35-year old long-term maize continuous cropping field experiment (Keszthely, Hungary). The weed flora was recorded on 1 June, 2003 in the 6-8-leaf development stage of maize. The effect of the increasing rates of fertilizers was analyzed and evaluated from the results of biomass production as well as the nutrient uptake of weeds and maize, respectively. On the experimental plots 9 weed species were registered at the date of sampling, from which 4 species were perennial and 5 species were annual ones. All the weeds were collected from 1 m² areas of each plot and the different weed species were separated from each other. The fresh and dry weights of the canopy of maize and the different weed species were measured. The nutrient (NPK) contents of maize and weed samples were measured in the laboratory. Total and species scale nutrient concentration, as well as per-unit nutrient uptake of maize and weeds were compared. The increasing rates of mineral fertilizers had a significant effect on the biomass production and on the nutrient uptake of weeds. Significant differences were also found between the biomass production and nutrient uptake of the different weed species.

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Influence of crop rotation and meteorological conditons on biodiversity of weed communities in spring barley (Hordeum vulgare L.)

Acta Agrobotanica ◽

10.5586/aa.2010.025 ◽

2012 ◽

Vol 63 (1) ◽

pp. 221-233 ◽

Cited By ~ 1

Author(s):

Magdalena Jastrzębska ◽

Maria Wanic ◽

Marta K. Kostrzewska

Keyword(s):

Crop Rotation ◽

Spring Barley ◽

Chenopodium Album ◽

Diversity Indices ◽

Weed Species ◽

Hordeum Vulgare L ◽

Winter Triticale ◽

Weed Diversity ◽

Species Diversity Indices ◽

Density And Biomass

The paper presents the analysis of changes in weed biodiversity in spring barley cultivated in the years 1990-2004 in crop rotation with a 25% proportion of this cereal (potato - spring barley - sowing peas - winter triticale), when it was grown after potato, and in crop rotation with its 75% proportion (potato - spring barley - spring barley - spring barley), when it was grown once or twice after spring barley. In the experiment, no weed control was applied. Every year in the spring (at full emergence of the cereal) and before the harvest, the composition of weed species and numbers of particular weed species were determined, and before the harvest also their biomass. On this basis, the constancy of species in particular years, Shannon-Wiener species diversity indices and diversity profiles according to Rényi were determined. Weed species richness increased linearly at all plots during the 15-year period. Chenopodium album was a constant and dominant species in terms of weed species density and biomass year after year. The quality of the plot had no clear influence on the diversity of weeds in barley. Weed density and biomass showed high year-to-year variability and a positive correlation with the amount of precipitation and a negative correlation with temperature during the period of the study. The significance of the correlation between the productivity of barley and weed diversity was not confirmed.

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Diversity of Weeds Species in Citrus Farms of Taymma (Tabuk, Saudi Arabia): Implication for Invasive Species Ecology

Biosciences Biotechnology Research Asia ◽

10.13005/bbra/2668 ◽

2018 ◽

Vol 15 (3) ◽

pp. 619-625

Author(s):

Salem Mesfir Al-Qahtani

Keyword(s):

Invasive Species ◽

Saudi Arabia ◽

Diversity Index ◽

Economic Loss ◽

Diversity Indices ◽

Gamma Diversity ◽

Weed Species ◽

Essential Information ◽

One Way Anova ◽

Species Ecology

Invasive species of weeds in agroecosystem is known as a critical problem which is associated with severe economic loss as they compete the crops for niche, water and nutrients. There is a lacking in the information about biology and ecology of weeds communities in agroecosystems of Saudi Arabia particularly citrus farms. The present study aimed to investigate the distribution and diversity of weeds in selected citrus farms of Taymma (Saudi Arabia). A total of 36 weed species belonging to 20 families were recorded in citrus farms of Taymma. The species Aizoon canariense, Artemisia seiberi, Morettia parviflora, Oxalis corniculata, Setaria viridis and Salsola imbricata were the dominant species in the citrus farms. The dominant family was Poacea, Asteraceae, Brassicaceae and Chenopodiaceae. The total number of weed species (gamma diversity index γ), ranged between 25 and 27. Three diversity indices were calculated; Shannon-Weiner (H’), Simpson (1-D) and Margalef. There was no significance differences in the three diversity measures among the selected citrus farms (One-way ANOVA Shannon-Weiner (H’); F2,12=0.025 and P=0.975, Simpson; F2,12=0.071 and P=0.932, Margalef; F2,12=0.113 and P=0.895). The variance in the species among the sites as expressed by beta diversity (β) varied slightly among the studied farms. The present study provides essential information about ecology of weeds in citrus agroecosystem. It is recommended that further ecological studies should be carried out to better understand the biological and environmental factors that structuring the weeds communities in arid region.

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The influence of strip cropping and weed control methods on weed diversity in dent maize (Zea mays L.), narrow-leafed lupin (Lupinus angustifolius L.) and oats (Avena sativa L.)

Acta Agrobotanica ◽

10.5586/aa.2013.065 ◽

2014 ◽

Vol 66 (4) ◽

pp. 185-194 ◽

Cited By ~ 2

Author(s):

Aleksandra Głowacka

Keyword(s):

Weed Control ◽

Control Method ◽

Chenopodium Album ◽

Dry Weight ◽

Weed Species ◽

Two Factors ◽

Weed Diversity ◽

Sole Cropping ◽

Weed Infestation ◽

The Subject

The experiment was conducted in 2008–2010 at the Experimental Station of the Faculty of Agricultural Sciences in Zamość, University of Life Sciences in Lublin. The research design included two factors: I. Method of cultivation – sole cropping and strip cropping (the cultivation of three plants: maize, narrow-leafed lupin and oats, in neighboring strips); II. Weed control method – mechanical and chemical. The subject of this study was weed infestation in maize, narrow-leafed lupin and oats. The greatest diversity of weeds was found in the narrow-leafed lupine crop, while the lowest diversity in maize. The dominant weed species in maize, lupine and oats were Echinochloa crus-galli, Chenopodium album and Galinsoga parviflora which ranged from 34% to 99% of the total number of weeds. Strip cropping clearly reduced the number of weeds per unit area in the narrow-leafed lupin and oat crops as well as the aboveground dry weight of weeds in all plant species. Chemical weed control significantly decreased both the number and weight of weeds in comparison with the mechanical method.

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Effect of tillage system on the structure of weed infestation of winter wheat

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2018164-12531 ◽

2019 ◽

Vol 16 (4) ◽

pp. e1009 ◽

Cited By ~ 6

Author(s):

Andrzej Woźniak

Keyword(s):

Species Composition ◽

Winter Wheat ◽

Diversity Index ◽

Gravimetric Method ◽

Weed Species ◽

Species Diversity Index ◽

Weed Distribution ◽

Tillage System ◽

Weed Infestation ◽

Ct System

The study aimed to evaluate the structure of weed infestation of winter wheat grown in different weeding systems: conventional tillage (CT), reduced tillage (RT), and herbicide treatment (HT). In CT system, shallow ploughing and pre-sow ploughing were conducted after the harvest of the previous crop. In RT system, shallow ploughing was replaced by cultivator tillage, whereas pre-sow ploughing by a tillage set. In HT system, shallow ploughing was replaced by spraying with glyphosate and pre-sow ploughing by cultivator tillage. At the tillering stage (22-23 in BBCH scale), species composition and number of weeds/m2 were determined with the botanical-gravimetric method, whereas at the stage of waxy maturity of wheat (82-83 BBCH) analyses were conducted for species composition as well as density, air-dry weight, and weed distribution in crop levels. The Shannon-Wiener’s diversity index (H’) and degrees of phytosociological constancy (S) of weeds were determined as well. The study showed that more weeds occurred in RT and HT systems than in the CT system and they produced higher biomass in RT than in CT and HT systems. The tillage system affected weed distribution in crop levels. In CT system, the highest weed density was identified in the ground and lower levels, whereas in RT and HT systems in the ground and middle levels. Values of the species diversity index (H’) indicate a similar diversity of weed species composition between weeding systems and more diverse between study years.

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Changes in weed infestation of spring barley depending on variable pluvio-thermal conditions

Acta Agrobotanica ◽

10.5586/aa.2015.027 ◽

2015 ◽

Vol 68 (3) ◽

pp. 233-240

Author(s):

Roman Krawczyk ◽

Roman Kierzek ◽

Kazimierz Adamczewski

Keyword(s):

Species Diversity ◽

Plant Protection ◽

Diversity Index ◽

Spring Barley ◽

Thermal Conditions ◽

Weed Species ◽

Dominance Index ◽

Species Dominance ◽

Wiener Diversity Index ◽

Weed Infestation

The aim of the study was to analyze segetal weeds present in spring barley against the background of changes in pluvio-thermal conditions observed over the last 20 years (1993–2012) at the Field Experimental Station of the Institute of Plant Protection – National Research Institute in Winna Góra, Poland. Based on the mean value of the Sielianinov hydrothermal coefficient for the three months of spring vegetation, i.e., April, May, and June, three classes of pluvio-thermal conditions (very dry, moderately dry, humid) were distinguished. The phytosociological stability of weed species analyzed during the study period was assessed and the Shannon–Wiener index of species diversity in the communities and the Simpson dominance index were calculated for segetal weeds present in spring barley.In the 20-year period analyzed, Chenopodium album and Viola arvensis exhibited the highest phytosociological stability and the highest abundance in the spring barley crop. Over the years analyzed, the dry spring vegetation periods were characterized by significant precipitation deficiency between late April and mid-June. In the years with favorable meteorological conditions, the weed species diversity measured by the Shannon–Wiener diversity index was higher than in the years with precipitation deficiency. In the very dry years, the species dominance index in the spring vegetation period was higher than in the wet years. The yield loss caused by weed infestation in the very dry years was higher by 6% as compared to moderately dry and wet years.

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Effect of various tillage operations and straw management on the occurence of weeds

Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis ◽

10.11118/actaun200553050133 ◽

2005 ◽

Vol 53 (5) ◽

pp. 133-142

Author(s):

Ivana Remešová

Keyword(s):

Winter Wheat ◽

Field Experiment ◽

Crop Rotation ◽

Spring Barley ◽

Soil Tillage ◽

Counting Method ◽

Weed Species ◽

Straw Management ◽

Weed Infestation ◽

Tillage Operations

The weed infestation was assessed in a field experiment at the Research Institute for Folder Crops Ltd., Troubsko near Brno in 2001−2004. Numbers of individual weed species were determined using a counting method on the area of 0.25 m2 in winter wheat stands within the 6-crop rotation (peas, winter wheat, spring barley, oilseed rape, winter wheat, winter wheat) in different variants of soil tillage and straw management. The highest weed infestation in all variants was found when winter wheat followed winter wheat. The highest number of weeds was assessed in the variant with stubble tillage to the depth of 0.12−0.15 m, planting with a precision drill and straw chopping. The lowest number of weeds was found in winter wheat after peas in the variant with incorporation of chopped straw using a tiller to 0.12−0.15 m and planting with a drilling combination, and in the variant where chopped straw was sprayed with the BETA-LIQ preparation, incorporation with a tiller to 0.12−0.15 m and planting with a drilling combination.

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On a Variational Definition for the Jensen-Shannon Symmetrization of Distances Based on the Information Radius

Entropy ◽

10.3390/e23040464 ◽

2021 ◽

Vol 23 (4) ◽

pp. 464

Author(s):

Frank Nielsen

Keyword(s):

Diversity Index ◽

Diversity Indices ◽

Shannon Diversity Index ◽

Probability Measures ◽

Variational Optimization ◽

Shannon Diversity ◽

Concept Of Information ◽

Jensen Shannon Divergence

We generalize the Jensen-Shannon divergence and the Jensen-Shannon diversity index by considering a variational definition with respect to a generic mean, thereby extending the notion of Sibson’s information radius. The variational definition applies to any arbitrary distance and yields a new way to define a Jensen-Shannon symmetrization of distances. When the variational optimization is further constrained to belong to prescribed families of probability measures, we get relative Jensen-Shannon divergences and their equivalent Jensen-Shannon symmetrizations of distances that generalize the concept of information projections. Finally, we touch upon applications of these variational Jensen-Shannon divergences and diversity indices to clustering and quantization tasks of probability measures, including statistical mixtures.

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