Phytosociological Survey Of Weeds Research Articles

Phytosociological Survey of Weeds on Degraded and Well-Managed Pastures: Agronomical and Ecological Implications

The objective of this research was to carry out a survey of weeds in pastures in the Middle Valley of Paraíba do Sul, Rio de Janeiro State, Brazil, in order to subsidize weed management and pasture recovery. Weed identification and plant count were carried out in pastures with four levels of degradation, classified as low (N1), moderate (N2), strong (N3) and very strong (N4), with five replications. Thirty-nine weed species were identified and distributed into16 botanical families. Poaceae, Asteraceae and Fabaceae were the most relevant families. The number and density of weeds increased as the level of degradation decreased. The relative importance of weed species varied with the level of degraded pasture. The main weeds found in N1 were Melinis minutiflora, Desmodium incanum, Croton lundianus, Andropogon bicornis, and Imperata brasiliensis; in N2: Paspalum notatum, Melinis minutiflora, Imperata brasiliensis, Sida rhombifolia, and Desmodium incanum; in N3: Paspalum notatum, Melinis minutiflora, Sida rhombifolia, Eupatorium maximilianii, and Imperata brasiliensis; in N4: Paspalum notatum, Melinis minutiflora, Cynodon dactilon, Eupatorium maximilianii, and Imperata brasiliensis. The similarity index was high, showing the homogeneity of weeds among areas. The predominant species, considering all areas, were in increasing order of importance: Cynodon dactilon, Melinis minutiflora and Paspalum notatum. Decision-making about applying control measures could be marked out when the plant density reached out or exceed the average of 3.58 plants m-2.

Phytosociological survey of weeds in the grapevine

Viticulture is expanding in the state of Espírito Santo, Brazil. Weed management is essential for the crop, so knowing the floristic composition of weeds in the vineyards makes this practice sustainable. This study aimed to evaluate the floristic composition of weed populations in grape crops in two seasons, considering different altitudes. The experiment was performed in four properties located in Santa Teresa, ES, Brazil, two of which were at altitudes above 500 m of and two below 500 m, in the winter (2018) and summer (2019) seasons. Weeds were identified with the square inventory method. The phytosociological analysis was based on absolute and relative parameters of frequency, density, dominance, importance value index, and relevance index, besides the diversity, evenness, and similarity indices. Fifty species, 41 genera, and 19 families were identified. The most representative families regarding the number of species were Asteraceae, Poaceae, and Malvaceae. In properties with higher altitudes, the species with the highest IVI was Pilea microphylla (L.) Liebm., in both seasons. In properties with lower altitudes, the highest IVI values were found for Malvastrum coromandelianum L. in the winter and Commelina benghalensis and Portulaca oleracea L. in the summer. The areas below 500 m of altitude showed the highest diversity and evenness indices. The proximity between the areas in both regions contributed to the increased similarity index. Altitude and time of the year contribute to the composition of the infesting community.

Phyto-sociological survey of weeds in direct seeded rice (Oryza sativa L.)

Field observation was carried out at Melbhuvanagiri block, (Valayamadevi, Periyanarkunam, AgaraAlambadi and Periyakuppam villages), Cuddalore district during 2020 to determine the phytosociologicalcharacters of weeds in direct seeded rice fields. The composition of the weed species in the fields wasevaluated by randomly throwing 0.25 m2 quadrate in 10 different locations in each village. Frequency,density, abundance and their relative values were calculated. Highest relative frequency, relative density,relative abundance and importance value index was observed with Echinochloacolona (L.)Link amonggrasses, Cyperus difformisL. among sedges and Eclipta alba (L.) Hassk among broad leaved weeds in all theobserved villages of direct seeded rice fields. Diversity indices were worked out for each village, amongthem Periyanarkunam village recorded the highest diversity indices (Shannon index (H’) of 2.234, Simpsonindex (D) of 0.873 and Evenness index (E) of 2.070) in direct seeded rice. Hence weeds were prominent inPeriyanarkunam village than all the observation sites.

Phytosociological survey of weeds in irrigated maize fields in a Southern Guinea Savanna of Nigeria

Maize is a food crop for millions of people in sub-Saharan Africa. However, severe weed infestation might cause significant yield loss. This study investigated weed composition, abundance and distribution in maize-based cropping systems in the Southern Guinea Savanna of Nigeria. Fields were surveyed between February and March 2022. The Importance Value Index (IVI) of each weed species was determined using relative frequency, relative density, and relative abundance. A total of 29 weed species from 15 families were identified. Poaceae (34.9 %) was the most prevalent weed family, followed by Cyperaceae (26.9 %) and Portulacaceae (12.8 %). The IVI showed that Cyperus rotundus (38.6), Portulaca oleraceae (29.4), Digitaria horizontalis (25.5), Brachiaria deflexa (24.2), Senna obtusifolia (17.6), Ageratum conyzoides (16.0), Cynodon dactylon (12.6), Phyllanthus niruri (11.1) and Eragrostis sp. (10.6) were the most dominant. Principal Component Analysis (PCA) ordination biplot revealed that Setaria pumila was strongly associated with sole maize cultivation, as was Desmodium scorpiurus with maize/rice intercropping, C. dactylon with maize/pepper, Euphorbia hirta with maize/cassava, and Cleome viscosa with maize/amaranthus intercropping. Special attention to these weed species is required when making an informed decision on the choice of weed control measures.to reduce yield losses in endemic areas.

Crop management and its effects on weed occurrences

The objective was to evaluate weed phytosociology and similarities between crop management systems in the Chapadões region. The experiment was conducted at in agricultural area located in the municipality of Chapadão do Sul, MS, during the 2016/17 harvest. Three crop managements strategies were used: (1) cotton/soybean/Urochloa, (2) millet/soybean/millet and (3) millet/soybean/crotalaria. A phytosociological survey of weeds was carried out during soybean cultivation and cover crops growth, in succession. The evaluation area for each management strategy was 0.5 ha. Soybean surveys were carried out in October and January, while the cover crop surveys were performed in February and May. The relative frequency (RF), relative density (RD), relative abundance (AR), and relative importance (RI) of weeds, Venn diagram, and Jaccard and Sorenson similarity indices were evaluated. The management area represented by the cotton/soybean/Urochloa rotation had fewer weed species than others. The species Cenchrus echinatus, Digitaria insularis, Digitaria sanguinalis, Eleusine indica and Commelina benghalensis had the highest phytosociological indeces among the monocotyledons. Attention is required for managing the dicotyledons Amaranthus deflexus, Conyza canadensis and Senna obtusifolia despite their low indices because of herbicide resistant cases. The highest indeces of similarity were found between managements areas 2 and 3, which did not rely on cotton cultivation prior to soybeans.

Phytosociological Survey of Weeds in Coffee Plants Irrigated Under Different Systems

The objective was to identify the species and quantify the importance value index of weeds in the cultivation of arabica coffee in two irrigation systems, at different times of the year, in the northern region of Minas Gerais. A phytosociological survey was carried out in each season of the year (spring, summer, autumn and winter) in an area cultivated with the species Coffea arabica, subjected to two irrigation systems (sprinkling and dripping). The coffee crop was implanted at a spacing of 3.5 m between rows and 0.7 meters between plants. The collection of weeds was performed using the standard method of the square inventory, which was launched between the lines of the crop. The identification of the species was carried out, the number of individuals was quantified, the dry mass, frequency, density, abundance, importance value index and coverage, and the similarity index. 33 weed species were identified, being the species with the highest IVI Euphorbia hirta, Brachiaria plantaginea, Digitaria horizontalis, Cyperus rotundus and Amaranthus spp. It was observed a higher occurrence of weeds from the monocot group in the sprinkler irrigation system while in the drip there were predominance of dicot plants.

Levantamento fitossociológico das plantas daninhas em diferentes frutíferas de clima temperado no Município de Lavras – MG

A fruticultura brasileira tem grande importância na economia, aparecendo como o terceiro maior produtor mundial. Neste contexto, o manejo de plantas daninhas torna-se indispensável do ponto de vista agronômico, pois competem por água, luz, nutriente e espaço, causando muitos prejuízos às culturas de interesse. Essas perdas se acentuam à medida que não são devidamente controladas, por este motivo, é realizado o levantamento fitossociológico, que permite conhecer a dinâmica das plantas daninhas e sua correta identificação. Objetivou-se com esse trabalho efetuar um levantamento fitossociológico das plantas daninhas existentes no cultivo de frutíferas de clima temperado no município de Lavras-MG. O levantamento foi realizado no setor de Fruticultura da Universidade Federal de Lavras (UFLA). Foi realizado o levantamento fitossociológico em 18 cultivares de Pereira (Pyrus spp.), sete cultivares de Macieira (Malus domestica L.), 22 cultivares de Pessegueiro (Prunus persica (L.) Batsch), sete cultivares de Framboesa, dez cultivares de Amora-Preta (Rubus spp.), além de área plantada com 11 cultivares de Caquizeiro (Diospyrus kaki L.), uma cultivar de Figueira (Ficus carica L.) e 34 cultivares de Marmeleiro (Cydonia oblonga e Chaenomelis sinensis L.). As identificações das plantas daninhas foram baseadas através de análise do material, fotografias e com consulta à literatura especializada, posteriormente a identificação, houve a classificação e análise da estrutura da comunidade, fazendo o agrupamento em famílias, nome científico, nome vulgar e quanto ao ciclo produtivo vegetal das espécies. Foram avaliadas Distribuição Espacial, Variância, Densidade, Frequência, Constância, Dominância, Valor de Importância, Índice de Valor de Importância e Avaliação de Similaridade. O levantamento fitossociológico evidenciou que a espécie Cyperus rotundus foi a espécie com maior IVI no cultivo da amoreira, framboesa, macieira e marmeleiro. Enquanto que a espécie Cynodon dactylon teve o maior IVI no cultivo das framboesas, pereiras e marmeleiros. Por outro lado, a espécie Brachiaria plantaginea atingiu o maior IVI no cultivo das macieiras. Por fim, a espécie Pennisetum clandestinum atingiu o maior IVI no cultivo dos caquizeiros. De acordo com o levantamento fitossociológico, deve-se verificar os métodos de controle utilizados como implementos agrícolas, formas de aplicação de inseticidas (sistêmicos ou contato), o sistema de irrigação que menos contribua para o desenvolvimento das espécies indesejáveis, e assim diminuir competição pela água, luz e nutrientes com o aumento da produtividade.

Floristic composition of weeds in a dystrophic Red-Yellow Argisol under the cultivation of cowpea, cv. BRS Novaera

Among the several factors that negatively influence cowpea culture, weeds have been responsible for the reduction of growth, development and productive performance of the crop, making it necessary to establish management strategies based on phytosociological studies of weed species in growing areas. Therefore, the objective of this research was to evaluate the floristic composition of weeds, aiming to identify the main species and their dynamics, and to consider their distribution in time and space as pertaining to the cultivation of a modern variety of cowpea, cv. BRS Novaera, in dystrophic Red-Yellow Argisol, in the Midnorth region of the state of Piauí, Brazil. The phytosociological survey of weeds was carried out in three sessions: the first one was immediately before the area was desiccated with glyphosate (15 days before sowing the cowpea), and the others were at 20 and 40 days after sowing (DAS). Following the quantification of species and number of individuals, the following phytosociological parameters were calculated: frequency and relative frequency; density and relative density; abundance and relative abundance; and importance value index. It was concluded that there were few changes in the floristic composition of the weed community according to the epoch of the phytosociological surveys. The main weed plants at 20 DAS of cowpea (vegetative phase) were Chamaesyce hirta, Digitaria insularis, Alternanthera tenella, Cleome affinis, Mollugo verticillata and Portulaca oleracea. At 40 days (reproductive phase), the weed species with a large establishment and acting as potential competitors with cv. BRS Novaera cowpea were Digitaria insularis, Chamaesyce hirta and Mollugo verticillata.

Phytosociological survey of weeds in passion fruit culture

O problema com plantas daninhas é um dos mais sérios e que são responsáveis pelos maiores gastos em seu controle, pois a disputa por água, nutrientes e luz pode causar uma diminuição significativa no rendimento da lavoura, depreciação na quantidade e na qualidade dos frutos. Desta forma, objetivou-se realizar o levantamento fitossociológico das plantas daninhas em área cultivada com a cultura do maracujá, na Universidade Federal de Alagoas – UFAL, Campus de Arapiraca. Foram realizadas 6 amostragens com quadrado vazado de 0,50 m2, onde as plantas daninhas foram coletadas ao nível do solo, separadas por espécie, contadas e levadas à estufa, até massa constante, para determinação da massa seca. A partir desses valores, determinaram-se as seguintes características: frequência de plantas daninhas, frequência relativa, densidade, densidade relativa, abundância, abundância relativa, massa seca relativa, índice de importância e índice de importância relativa. Foram identificadas 18 espécies e 10 famílias botânicas, sendo 13 dicotiledôneas e 5 monocotiledôneas, a família Asteraceae foi a mais representativa, seguida pela Poaceae. Entre as dicotiledôneas, a Asteraceae apresentou maior número de espécies infestantes com 6 espécies. Nicandra physaloides Gaertn. Solaneceae apresentou maior índice de importância relativa (IVIr), 94,88 e em seguida por Amaranthus hybridus L. Amaranthaceae com IVIr de 1,68. O menor valor de IVIr foi obtido por Sida spinosa L. Malvaceae.

Floristic composition of weeds in a dystrophic Red-Yellow Argisol under the cultivation of cowpea, cv. BRS Novaera

Among the several factors that negatively influence cowpea culture, weeds have been responsible for the reduction of growth, development and productive performance of the crop, making it necessary to establish management strategies based on phytosociological studies of weed species in growing areas. Therefore, the objective of this research was to evaluate the floristic composition of weeds, aiming to identify the main species and their dynamics, and to consider their distribution in time and space as pertaining to the cultivation of a modern variety of cowpea, cv. BRS Novaera, in dystrophic Red-Yellow Argisol, in the Midnorth region of the state of Piauí, Brazil. The phytosociological survey of weeds was carried out in three sessions: the first one was immediately before the area was desiccated with glyphosate (15 days before sowing the cowpea), and the others were at 20 and 40 days after sowing (DAS). Following the quantification of species and number of individuals, the following phytosociological parameters were calculated: frequency and relative frequency; density and relative density; abundance and relative abundance; and importance value index. It was concluded that there were few changes in the floristic composition of the weed community according to the epoch of the phytosociological surveys. The main weed plants at 20 DAS of cowpea (vegetative phase) were Chamaesyce hirta, Digitaria insularis, Alternanthera tenella, Cleome affinis, Mollugo verticillata and Portulaca oleracea. At 40 days (reproductive phase), the weed species with a large establishment and acting as potential competitors with cv. BRS Novaera cowpea were Digitaria insularis, Chamaesyce hirta and Mollugo verticillata.

Phytosociology of Weeds in Off-Season Maize Crops in the Middle Paranapanema

ABSTRACT: This work is the first one after the consolidation of the introduction of the RR technology in maize and soybean crops, following weed surveys previously carried out in the region of the Middle Paranapanema, São Paulo state. The objective was to carry out a phytosociological survey of weeds in off-season maize crops no-tillage, in the same properties where the studies had been previously carried out, in the described region, taking into account the management of the weed community adopted by farmers, and the percentage of plant coveron the soil. The surveys were carried out in 19 farms conducted under no-tillage systems, with off-season maize cultivated in soybean succession, both RR crops, in nine municipalities of the São Paulo region of the Middle Paranapanema, in 2016. The main weeds were Bidens pilosa, Cenchrus Echinatus, Commelina benghalensis, Digitaria horizontalis, Gnaphalium spicatum, Leonotis nepetifolia, Raphanus sativus and Sonchus oleraceus. The predominant management of weeds was the chemical method, and in the vast majority of properties, control was based on the use of glyphosate and atrazine. The other used herbicides are nicosulfuron, chlorimuron-ethyl, clethodim, haloxyfop, tembotrione and 2,4-D, almost always associated with the EPSPs inhibitor. The soil cover with straw, found at the time of the evaluation, had no correlation with the presence or absence of the weeds.

Interference of the Association Oxyfluorfen + Flumioxazin and the Addition of Mineral Oil on a Phytosociological Survey

ABSTRACT: Phytosociological studies are extremely important for the management of weeds in cultivated areas. Thus, the goal of this work was to evaluate the interference of mineral oil associated with oxyfluorfen and flumioxazin, through the phytosociological survey of weeds. Therefore, this experiment was conducted in a 2 x 5 + 1 factorial design and with four replications; the following oxyfluorfen + flumioxazin associations were evaluated: 240 + 50, 192 + 40, 144 + 30, 96 + 20 and 48 + 10 g a.i. ha-1, with and without the addition of mineral oil, including a control sample without application. Thirty days after the application, plant density, frequency and abundance of species were determined, and so were frequency, density and relative abundance, as well as the importance value index. Results indicate that the application of the mixture oxyfluorfen + flumioxazin, regardless of the addition of the mineral oil, provided a great population of Poaceae. The species Digitaria horizontalis and Brachiaria decumbens showed a higher importance value index in all treatments. Families with greater representation as for number of species were Poaceae, Asteraceae, Fabaceae and Rubiaceae. The addition of oil and different doses of the mixture oxyfluorfen + flumioxazin did not affect the population of weeds, compared to the mixture without mineral oil.

Phytosociological survey of weeds in cocoa plantation

Phytosociological survey of weeds in cocoa plantation

Phytosociology of Weeds in Cultivation of Two Varieties of Cassava1

ABSTRACT This study has aimed to carry out a phytosociological survey of weeds in different collection periods, in cassava crops of two varieties grown in two consecutive years. The varieties were Pão, of the sweet class, and Racha-terra, of the bitter class. The weeds surveys were performed at 28, 56, 84, 112, 140, 168, 196, 224, 252, 280 and 308 days after planting in the experimental units of each variety. For weeds sampling, a sampler with an area of 0.25 m2 released twice at random in the floor area of the treatments was used. The phytosociological survey quantified 5,708 individuals distributed in 17 families, represented by 32 species, of which 25 were dicotyledonous and seven were monocotyledonous. The most representative families in number of species were Euphorbiaceae and Poaceae, followed by Cyperaceae and Fabaceae. The most important species in the two growing seasons were Axonopus affinis, Mimosa pudica, Spermacoce verticillata and Paspalum multicaule. Other important species of the Poaceae family were Axonopus affinis, Axonopus fissifolius and Homolepis aturensis.

Phytosociological Survey of Weeds in Areas of Crop-Livestock Integration

The dynamics of the weeds in the areas of crop-livestock integration is constantly changing depending on the various uses of the area. This study identified and quantified the floristic composition of weeds in areas of integration of maize for silage with Urochloa ruziziensis cv. Common at different densities of grass (0, 4 and 10 kg&middotha-1) to grazing of beef cattle. The experimental design was completely randomized. A square of side0.5 m(0.25 m2area) was launched 24 times in each study area. The survey was conducted at the grain filling stage of maize. The specie contained in each frame were identified and counted. The phytosociological survey identified 9 families of weeds in areas assessed, with 7 families in every area of integrated cultivation maize with Urochloa ruziziensis at densities of 10 kg&middotha-1 and 4 kg&middotha-1 and 8 families in the area of maize cultivated alone. The Asteraceae family was the most represented in number of species. Sida spp (Malvaceae) showed greater potential to cause damage to maize. Urochloa ruziziensis at planting density of 10 kg&middotha-1 provided greater competition with weeds in the integration with maize.