scholarly journals Weed population dynamics in rice crops resulting from post-emergent herbicide applications

2017 ◽  
Vol 70 (1) ◽  
pp. 8035-8043
Author(s):  
Javier Ramírez ◽  
Verónica Hoyos ◽  
Guido Plaza
Keyword(s):  
Population Dynamics ◽  
Community Structure ◽  
Relative Frequency ◽  
Importance Value Index ◽  
Importance Value ◽  
Weed Population ◽  
Weed Communities ◽  
Weed Population Dynamics ◽  
Importance Index ◽  
Before And After

Studies on weed population dynamics are based on observing and recording changes in weed communities in response to effects of disturbances in crop management. The present study aimed to evaluate weed population dynamics in rice crops in Tolima, Colombia, resulting from post-emergent herbicide applications. Sampling was carried out in 0.1% of the cultivated area, marking out a 1 ha area in each commercial lot. Samples were taken before and after post-emergent applications. Evaluated variables were frequency, density, and cover. The data were analyzed using the Importance Value Index (IVI). Results demonstrated that Echinochloa colona was the most important weed of all of the evaluated zones, before and after post-emergent herbicide applications. Other notable species included Digitaria ciliaris, Cyperus iria and Ischaemum rugosum. Relative frequency variable was the most influential on the importance index of the species. Furthermore, herbicide applications generated changes in the community structure in the evaluated zones and in each evaluation.

scholarly journals Field study on weeds incidence in rapeseed (Brassica campestris L.).

2019 ◽  
Vol 26 ◽  
pp. 1-6
Author(s):  
MT Akhter ◽  
PB Kundu ◽  
NK Paul
Keyword(s):  
Relative Frequency ◽  
Brassica Campestris ◽  
Cynodon Dactylon ◽  
Cyperus Rotundus ◽  
Importance Value Index ◽  
Importance Value ◽  
Weed Population ◽  
Quantitative Characters ◽  
Weed Flora ◽  
Weed Infestation

A survey was conducted to highlight the weed flora infesting rapeseed in the experimental field of Rajshahi University. Frequency (F), density (D), abundance (A), relative frequency (RF), relative density (RD), relative abundance (RA) and importance value index (IVI %) of weeds were calculated in rapeseed field. The objective of the study was to study the weeds and their quantitative characters. Weed infestation was studied in three rapeseed varieties (BARI Sharisha 14, BINA Sharisha 5 and 6). The weed population was studied using quadrat. The species which had 100% frequency values were Cyperus rotundus, Cynodon dactylon, Ammania baccifera, Echinochloa crusgalli and Leucas lavendulifolia. Other species had 50% or less than 50% frequency values. The highest frequency, density, abundance and importance value index were exhibited by Cyperus rotundus. J. bio-sci. 26: 01-06, 2018

scholarly journals Komposisi Jenis, Struktur Komunitas, dan Keanekaragaman Mangrove Asosiasi Langge Kabupaten Gorontalo Utara-Provinsi Gorontalo

2019 ◽  
Vol 17 (1) ◽  
pp. 181
Author(s):  
Sukirman Rahim ◽  
Dewi Wahyuni K Baderan
Keyword(s):  
Community Structure ◽  
Species Diversity ◽  
Relative Density ◽  
Relative Frequency ◽  
Diversity Index ◽  
Mangrove Forests ◽  
Chromolaena Odorata ◽  
Importance Value Index ◽  
Importance Value ◽  
Nypa Fruticans

Hutan mangrove Langge yang terdapat di Kecamatan Anggrek Kabupaten Gorontalo Utara memiliki keunikan dari pola zonasi dan keanekaragaman jenis. Hal ini yang menjadikan hutan mangrove di kawasan tersebut sebagai objek wisata tracking mangrove yang dikenal dengan nama “mangrove in love. Hutan mangrove memiliki berbagai fungsi ekologis yang sangat kompleks yakni sebagai daerah pemijahan  (spawing ground), tempat asuhan (nursery ground), dan tempat mencari makan (feeding ground) biota laut yang beraneka jenis dan memiliki fungsi ekonomis diantaranya buah mangrove dapat diolah menjadi berbagai produk kue dan sumber pangan alternatif pengganti beras. Penelitian ini bertujuan untuk : 1) untuk mengetahui komposisi jenis mangrove asosiasi; 2) untuk mengetahui struktur komunitas dari hutan mangrove Langge; dan 3) nilai Indeks Keanekaragaman. Adapun metode yang digunakan dalam penelitian ini adalah metode jalur berpetak (kombinasi plot dan transek). Jumlah spesies yang ditemukan akan dilihat untuk menjadi dasar penentuan komposisi jenis. Untuk pengkuran struktur komunitas mangrove dengan melakukan perhitungan terhadap Kerapatan Relatif (KR) dan Frekuensi Relatif (FR). Selanjutnya data yang didapatkan ditabulasikan untuk memperoleh nilai Indeks Nilai Penting (INP). Perhitungan keanekaragaman jenis menggunakan rumus (Sannon-wienner). Hasil penelitian menemukan 12 spesies tumbuhan mangrove asosiasi yakni Acanthus spinosus, Chromolaena odorata, Crassocephalum sp, Calotropis gigantean, Ipomea pes-caprae, Ricinus communis Excoecaria agallocha, Scaevola taccada, Spinifex littoreus, Terminalia catappa, Derris trifoliate dan Nypa fruticans. Struktur komunitas menunjukkan Chromolaena odorata memiliki nilai INP sebesar 33,2%, Kerapatan Relatif sebesar 24,91%, dan Frekuensi Relatif sebesar 8,33%.  Spesies dengan nilai INP terendah dimiliki oleh Nypa fruticans yaitu sebesar 9,14%, Kerapatan Relatif sebesar 0,81%, dan Frekuensi Relatif sebesar 8,33%. Nilai Indeks Keanekaragaman (H’) mangrove asosiasi sebesar 2,175 dan termasuk dalam kriteria tingkat keanekaragaman sedang. Data yang diperoleh ini dapat digunakan dalam pengelolaan hutan mangrove di Gorontalo Utara serta dapat menjadi database dalam usaha konservasi mangrove guna mengurangi efek pemanasan global.Langge mangrove forest located in the District of North Gorontalo District Orchid has a uniqueness of zoning patterns and keanekragaman types. This is what makes the mangrove forests in the region as a tourist attraction tracking mangrove known as the "mangrove in love. Mangrove forests have a variety of ecological functions is very complex which is a spawning area (spawing ground), point of care (nursery grounds), and foraging (feeding ground) various types of marine life and has the economic function of which pieces of mangrove can be processed into various products cake and alternative food sources instead of rice. This study aims to: 1) to determine the association of mangrove species composition; 2) to determine the community structure of mangrove forests Langge; and 3) the value of diversity index. The method used in this study is a terraced path method (combination of plots and transects). The composition of the types of views based on the number of species found. For sizing mangrove community structure by calculating the Relative Density (KR) and Relative Frequency (FR). Then the data obtained are tabulated to get the value of Importance Value Index (IVI). Calculation of species diversity using the formula (Sannon-wienner). The study found an association of twelve species of mangrove plants and the relative dominance (DR), then the data obtained are tabulated to get the value of Importance Value Index (IVI). Calculation of species diversity using the formula (Sannon-wienner). The study found an association of eight species of mangrove plants and the relative dominance (DR), then the data obtained are tabulated to get the value of Importance Value Index (IVI). Calculation of species diversity using the formula (Sannon-wienner). The study found an association of twelve species of mangrove plantsnamely Acanthus spinosus, Chromolaena odorata, Crassocephalum sp, Calotropis gigantean, Ipomea pes-caprae, Ricinus communis Excoecaria agallocha, Scaevola taccada, Spinifex littoreus, Terminalia catappa, Derris trifoliate dan Nypa fruticans. Community structure showed Chromolaena odorata has a value of IVI of 33,2%, amounting to 24,91% Relative Density and Relative Frequency of 8,33%. The species with the lowest IVI owned by Nypa fruticans that is equal to 9,14%, 0,81% Relative Density and Relative Frequency of 8,33%. Values Diversity Index (H ') at 2.175 and mangrove associates included in the criteria for a medium level of diversity. The data obtained can be used in the management of mangrove forests in North Gorontalo and can be a database of mangrove conservation efforts to reduce the effects of global warming.

scholarly journals Phytosociology in Degraded and Renewed Pastures in Agrosilvopastoral Systems

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
R.C. DIAS ◽  
M.V. SANTOS ◽  
E.A. FERREIRA ◽  
T.G.S BRAZ ◽  
L.V. FIGUEIREDO ◽  
...  
Keyword(s):  
Similarity Index ◽  
Weed Species ◽  
Importance Value Index ◽  
Importance Value ◽  
Brachiaria Decumbens ◽  
Agrosilvopastoral Systems ◽  
Before And After ◽  
One Year ◽  
Sida Cordifolia

ABSTRACT: In pastures, the incidence of weeds reduces the productivity and quality of forage. The identification of the weed species in pastures is fundamental to choose the renewal method. Thus, the objective of this work was to perform phytosociology before and after the renewal of a Brachiaria decumbens pasture, with the implantation of agrosilvopastoral systems. Eighteen different crop arrangements for pasture renewal were evaluated. The renewal systems were by eucalyptus integration (at 12 x 2 m or 12 x 3 m spacings) with maize, Brachiaria brizantha cv. Marandu (palisade grass) and/or Macrotyloma axillare (perennial horsegram), or monoculture and intercropping of palisade grass and perennial horsegram, as well as the evaluation of the application or not of the herbicide bentazon, at the recommended dose for maize crops (0.72 kg ha-1). Relative frequency, relative density, relative abundance, relative dominance, coverage value index, importance value index, dry matter and similarity index were evaluated. In the first survey, before the pasture renewal, 23 plant species were identified. After the implantation of agrosilvopastoral systems, the species Sida cordifolia, Lantana camara and B. decumbens were the only occurring ones before and after the renewal of the pasture with agrosilvopastoral systems. The use of palisade grass and the application of the herbicide were efficient in controlling weeds. In systems that contained palisade grass and perennial horsegram, the latter was not found in the survey conducted one year after the implantation.

Weed Population Dynamics and Weed Control in the Peruvian Amazon

1990 ◽  
Vol 82 (1) ◽  
pp. 102-112 ◽  
Author(s):  
Jane Mt. Pleasant ◽  
R. E. McCollum ◽  
H. D. Coble
Keyword(s):  
Population Dynamics ◽  
Weed Control ◽  
Peruvian Amazon ◽  
Weed Population ◽  
Weed Population Dynamics

Diversity of Weeds and Population Dynamics of Predators and Prey Present in Wheat-Mustard Ecosystem at Paklihawa, Rupandehi, Nepal

2018 ◽  
Vol 35 (1) ◽  
pp. 173-181
Author(s):  
S. Khanal ◽  
S. Adhikari ◽  
A. Bhattarai ◽  
S. Shrestha
Keyword(s):  
Population Dynamics ◽  
Chenopodium Album ◽  
Effect Of Temperature ◽  
Weed Species ◽  
Importance Value Index ◽  
Importance Value ◽  
Mustard Aphid ◽  
Wooden Frame ◽  
Index Value ◽  
The Given

A study was conducted at Institute of Agriculture and Animal Science (IAAS), Paklihawa Rupandehi, agronomy field to study the diversity of weeds and population dynamics of predators and prey in wheat-mustard ecosystem. The study was conducted by quadrate sampling method using the wooden frame by selecting 40 sample spots, and locating its coordinates. Predator, prey, some of the beneficial and harmful insects as well as weed species was recorded in 5 days interval in the study. Relationships between the population of the mustard aphid and wheat aphid, lady bird beetle to maximum and minimum temperature were recorded in order to know the effect of temperature in relation to population density. Number of mustard aphid and its nymph has shown the positive significant relationship with the population of the spider in the wheat mustard ecosystem. Shannon Weiner Index value was calculated and the species richness was found to be 2.63 with the effective number of species value 9. The species evenness value was found to be 0.83 in the studied ecosystem which signifies that the given weed ecosystem is somewhat even. The importance value index (IVI) of the given ecosystem with the value of different weed species was calculated and it was found that the weed Anagalis arvensis was ranked as first with the IVI value of 57.98 following Vicia sativa and Chenopodium album. This signifies that the species Anagalis arvensis has greater control over the wheat mustard ecosystem of Paklihawa, Rupandehi.

scholarly journals Ervas daninha em pastagens: uma abordagem fitossociológica nas áreas do Ceará

Agrarian ◽  
2019 ◽  
Vol 12 (45) ◽  
pp. 279-285
Author(s):  
Josefa Maria Francieli da Silva ◽  
Hercules Gustavo Santos Sarmento ◽  
Hellen Thayse Nascimento Araújo ◽  
Alexandre Bosco de Oliveira ◽  
Lamartine Soares Cardoso de Oliveira
Keyword(s):  
Relative Frequency ◽  
Similarity Index ◽  
Cyperus Rotundus ◽  
Weed Species ◽  
Importance Value Index ◽  
Importance Value ◽  
Brachiaria Decumbens ◽  
The One ◽  
Absolute Dominance ◽  
Nicandra Physalodes

The aim of this study was to study the phytosociology of weed species in areas of pasture cultivated with Brachiaria decumbens and Cynodon sp. (Tifton 85), in Ceará State, Brazil. The square inventory methodology was used in order to assess the weed community. Weed samples were quantified and classified by family, genus and species, using books and classification keys. The classification and quantification data of species allowed to calculate the following phytosociological variables: frequency (F), relative frequency (Fr), density (D), relative density (Dr), absolute dominance (DoA), relative dominance (DoR), importance value index (IVI), and similarity index (IS). The Amaranthaceae family was the one with the greatest intensity of species in both areas, represented mainly by Alternanthera tenera colla and Amaranthus viridis. In the area cultivated with B. decumbens, Cyperus rotundus presented higher results for frequency, density and abundance. In the Tifton 85 area, Nicandra physalodes presented higher values of density and abundance. The similarity of weed populations in pasture areas was 42.11%, with four species common to both areas.

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