scholarly journals EFFECTS OF COMPETITION AND WATER DEFICIENCY ON SUNFLOWER AND WEED GROWTH

2019 ◽  
Vol 32 (2) ◽  
pp. 318-328 ◽  
Author(s):  
MURILO MEIRA SOARES ◽  
CLÁUDIA DAIANNY MELO FREITAS ◽  
FERNANDO SARMENTO DE OLIVEIRA ◽  
HÉLIDA CAMPOS DE MESQUITA ◽  
TATIANE SEVERO SILVA ◽  
...  
Keyword(s):  
Water Deficit ◽  
Block Design ◽  
Dry Mass ◽  
Co2 Assimilation ◽  
Water Deficiency ◽  
Weed Species ◽  
Negative Effects ◽  
Weed Interference ◽  
Weed Growth ◽  
Randomized Block Design

ABSTRACT In the agricultural environment, the occurrence of biotic and abiotic stresses, such as weed interference and soil water deficit is common. However, little is known about the effects of the interaction of these stresses on the growth of cultivated crops and weed species. Thus, the objective of this study was to evaluate the effects of competition and water deficiency on the growth of sunflowers and weeds. The experiment was performed in a randomized block design with four replications. The treatments were arranged in a 5 × 2 factorial design, with the first factor corresponding to the competition arrangements between the species (sunflower + Waltheria indica; sunflower + Amaranthus spinosus; and sunflower, W. indica, and A. spinosus in monoculture without competition) and the second factor corresponding to water regimes (irrigated and water deficit). The water deficit regime was established when the sunflower plants had six expanded leaves (V6 stage) and was maintained until the rate of CO2 assimilation of the plants reached values close to zero (6 days), after which irrigation was resumed and maintained until 40 days after emergence, when the plants were collected and evaluated. The growth components evaluated were plant height, leaf area, dry leaf mass, dry stem mass, dry root mass, and total dry mass. Competition between plants decreased sunflower, W. indica, and A. spinosus growth. W. indica and A. spinosus aggravated the negative effects of water deficiency on sunflower growth. The water deficit regime did not affect the growth of W. indica. A. spinosus was more competitive with the sunflower than was W. indica.

scholarly journals MORPHOLOGICAL AND PRODUCTIVE CHARACTERIZATION OF FORAGE CACTUS VARIETIES

2015 ◽  
Vol 28 (3) ◽  
pp. 230-238 ◽  
Author(s):  
PHILIPE LIMA DE AMORIM ◽  
JANAINA AZEVEDO MARTUSCELLO ◽  
JOSÉ TEODORICO DE ARAÚJO FILHO ◽  
DANIEL DE NORONHA FIGUEIREDO VIEIRA DA CUNHA ◽  
LIANA JANK
Keyword(s):  
Block Design ◽  
Morphological Characteristics ◽  
Correlation Coefficients ◽  
Dry Mass ◽  
Negative Effects ◽  
Breeding Programs ◽  
Area Index ◽  
Promising Alternative ◽  
Randomized Block Design ◽  
Use Efficiency

ABSTRACT: Cultivars of the genus Nopalea are known in Brazil for being tolerant to cochineal carmine attacks, thus making the cultivation of this genus a promising alternative for mitigating the negative effects of this insect on the production of biomass. With the objectives of characterizing morphologically spineless forage cactus varieties and identify morphological characteristics that may be the focus in spineless forage cactus breeding programs, an experiment was conducted in a completely randomized block design with 11 treatments and four replications. The variety Alagoas showed the highest values of weight, area and volume of cladodes. The varieties Negro Michoacan F7 and V7, Tamazunchale V12 showed the highest values of the cladode area index, the total volume of cladodes and total fresh mass production. The varieties Negro Michoacan V7 and F7 presented the highest water use efficiency and dry mass yield. Cladode volume showed the highest correlation coefficients with the fresh weight of cladodes. Aiming the release of varieties for biomass production, varieties Negro Michoacan F7, V7 and Tamazunchale V12 may substitute the Miúda variety. The number and cladode area index may be used as criteria for selection of superior varieties in breeding programs.

scholarly journals Interference Periods in Soybean Crop as Affected by Emergence Times of Weeds

2018 ◽  
Vol 36 (0) ◽  
Author(s):  
R.R. ZANDONÁ ◽  
D. AGOSTINETTO ◽  
B.M. SILVA ◽  
Q. RUCHEL ◽  
D.S. FRAGA
Keyword(s):  
Weed Management ◽  
Critical Period ◽  
Block Design ◽  
Crop Productivity ◽  
Dry Mass ◽  
Weed Interference ◽  
Randomized Block Design ◽  
Intermediate Time ◽  
Crop Cycle ◽  
Weed Emergence

ABSTRACT: Weeds emergence times modify competition with crops. Thus, the hypothesis was that the increase in weed emergence flow decreases the period prior to interference (PPI) in soybeans and increases the critical period of interference prevention (CPIP). The objective was to determine the PPI and the CPIP of weeds in soybean crops as affected by the preferred time of weeds emergence flow. Three experiments were conducted in the field in a randomized block design with four replications. The treatments were arranged in a factorial design with factor A consisting of coexistence or weed control in soybeans and factor B for eight periods (0, 7, 14, 21, 28, 35, 42 and 135 days after crop emergence (DAE)). The numbers of emerged plants and weed dry mass by genus and crop productivity were evaluated. The weed interference in culture during all the crop cycle reduces the soybean average yield 73, 94 and 89% in the first, second and third sowing times, respectively. Chemical control may be adopted at the end of PPI, which must be done at 14, 15 and 5 DAE crop, for the first, second, third times, respectively. The sowing in advance and intermediate time of recommendation increase the PPI in about 10 days, favoring the weed management in soybean crops.

scholarly journals Weed Interference on the Accumulation of Dry Mass and Macronutrients of Eggplant ‘Nápoli’

2019 ◽  
Vol 37 ◽  
Author(s):  
L.J.P. MARQUES ◽  
M.S. BIANCO ◽  
S. BIANCO ◽  
A.B.C. FILHO ◽  
W.R. CERVEIRA JR ◽  
...  
Keyword(s):  
Mass Distribution ◽  
Mineral Nutrition ◽  
Block Design ◽  
Dry Mass ◽  
Reproductive Organs ◽  
Agricultural Crops ◽  
Weed Interference ◽  
Maximum Reduction ◽  
Randomized Block Design ◽  
Growth And Nutrition

ABSTRACT: The presence of weeds may affect both growth and nutrition of agricultural crops due to interference. The objective was to evaluate the interference of weeds in the dry mass distribution and in the accumulation of dry mass and macronutrients in eggplant. The treatments consisted of increasing weed-free and weedy periods (0-14, 0-28, 0-42, 0-56, 0-70, 0-84, 0-98, 0-112, 0-126, 0-140 and 0-154 days after transplanting) in eggplant ‘Nápoli’. The experiment was arranged in a randomized block design with three replicates. Weeds affected the distribution of dry mass between vegetative and reproductive organs of eggplant. There was a significant reduction in the accumulation of dry mass and macronutrients when weeds grew with eggplant crop beyond 42 days after transplanting, reaching the maximum reduction of 79%, 75%, 80%, 82%, 83%, 83% and 80% in the accumulation of dry mass, K, N, Ca, Mg, P and S, respectively. Therefore, the weed community significantly affects the growth and mineral nutrition of eggplant ‘Napoli’, and there should be no weed-crop coexistence beyond 28 days after seedling transplanting.

scholarly journals Effect of Trinexapac-Ethyl, at Two Application Timings, on the Initial Development of Eucalyptus under Water Deficit

2019 ◽  
Vol 37 ◽  
Author(s):  
A.L. BACHA ◽  
P.F.R.B. MARTINS ◽  
P.L.C.A. ALVES ◽  
R.C. PAULA
Keyword(s):  
Water Deficit ◽  
Block Design ◽  
Co2 Assimilation ◽  
Initial Growth ◽  
Initial Development ◽  
Application Timing ◽  
Hormetic Effect ◽  
Randomized Block Design ◽  
Net Co2 Assimilation ◽  
Positive Effect

ABSTRACT: Eucalyptus plants are sensitive to stress during their initial development, and water deficit is the most important one. Thus, the hormetic effect caused by the application of chemical products may be a factor that allows plants to tolerate such stresses. The objective of this study was to evaluate the effects of trinexapac-ethyl on the initial growth of Eucalyptus urophylla (Clone I-144), under water deficiency, at two application timings (before planting - BP; and after planting - AP). Two experiments were conducted simultaneously in a greenhouse for 74 days after planting (DAP) eucalyptus in 15 L pots. Treatments consisted of three trinexapac-ethyl doses (0.0, 30, and 60 g a.i. ha-1) and two water conditions (with and without water deficit). A complete randomized block design was used, in a 3 x 2 factorial arrangement, with five replications. At the BP application timing, trinexapac-ethyl was sprayed at 0 DAP, and at the AP timing, at 24 DAP. In both experiments, plant height, diameter, leaf area, dry matter, total relative chlorophyll content and gas-exchange were evaluated. There was a positive effect for the net CO2 assimilation rate at 27 and 40 DAP, for AP and BP, respectively. Eucalyptus plants, without water deficit, presented higher growth, regardless of the application timing. In conclusion, the application of trinexapac-ethyl before planting caused a positive effect on the height and diameter of eucalyptus; and the application timing influenced, in different ways, the evaluated characteristics, not having harmful effects on any of them.

scholarly journals Weed Growth and Dry Matter Partition Under Water Restriction

2016 ◽  
Vol 34 (4) ◽  
pp. 701-708 ◽  
Author(s):  
M.F.P. LIMA ◽  
J.L.D. DOMBROSKI ◽  
F.C.L. FREITAS ◽  
J.R.S. PINTO ◽  
D.V. SILVA
Keyword(s):  
Leaf Area ◽  
Water Deficit ◽  
Dry Matter ◽  
Dry Mass ◽  
Water Restriction ◽  
Weed Species ◽  
Commelina Benghalensis ◽  
Weed Growth ◽  
Cultivated Species ◽  
Number Of Leaves

ABSTRACT The capacity of a weed to adapt to the restriction of growth factors is directly related to its ability to compete for those resources with the cultivated species. An experiment was conducted to evaluate the effect of water restriction on the growth and biomass partitioning of four species of weeds. The experimental design used randomized blocks, with five replications. The treatments were arranged in a 4 x 2 factorial, with the first factor being the weed species (Waltheria indica, Crotalaria retusa, Cleome affinis and Commelina benghalensis) and the second, two water regimes: daily irrigation (Irr) and water restriction (WR). The number of leaves, leaf area, dry mass of the plant and its parts (root, stem and leaf), and the mass distribution among different organs (roots, leaves and stems) were determined. The water deficit in the soil increased the root dry matter for C. retusa, W. indica and C. benghalensis, however, it did not alter the mass of the stem of the weeds. C. retusa and W. indica suffered a reduction on the number of leaves, leaf area, dry matter of the leaves and the plant dry matter under water deficit. W. indica and C. retusa had a reduction on the percentage of biomass allocated to the leaves, and an increment on the percentage of the roots mass, while C. benghalensis and C. affinis had an increase only on the roots mass.

scholarly journals Interference Periods of Raphanus raphanistrum L. in Sunflower Crop

2020 ◽  
Vol 38 ◽  
Author(s):  
D. AGOSTINETTO ◽  
N. WESTENDORFF ◽  
R.R. ZANDONÁ ◽  
A.R. ULGUIM ◽  
A.C. LANGARO
Keyword(s):  
Block Design ◽  
Dry Mass ◽  
Wild Radish ◽  
Raphanus Raphanistrum ◽  
Total Period ◽  
Weed Interference ◽  
Randomized Block Design ◽  
Development Cycle ◽  
Sunflower Crop ◽  
Crop Cycle

ABSTRACT: Raphanus raphanistrum L. (wild radish) stands out among the weeds that cause greatest damage to the sunflower crop, due to the development cycle and adaptability. The objective of this research was to determine interference periods of sunflower interacting with wild radish, and the effects of competition on yield and its components. The experiment was conducted in the field in a randomized block design with four replications. The treatments were arranged in a factorial design with factor A composed of wild radish coexistence or control in sunflower, and factor B, for eight periods (0, 7, 14, 21, 28, 35, 42 and 135 days after crop emergence). It was evaluated height, diameter of chapters, achene yield and dry matter of weeds and crop. The presence of wild radish adversely affects the accumulation of dry mass, head diameter, thousand grain weight and reduces sunflower productivity when the wild radish interacts during the whole crop cycle, but does not affect on plant height. Chemical control of wild radish may be adopted at the end of period prior to interference, which for sunflower crop is 13 DAE, and the application is sufficient to avoid weed interference until the end of the total period of interference prevention which occurs until 17 days after crop emergence.

scholarly journals DINÂMICA POPULACIONAL DE PLANTAS DANINHAS EM ÁREAS COM SORGO SACARINO E GRANÍFERO COM DIFERENTES ESPAÇAMENTOS E DENSIDADES DE SEMEADURA

2018 ◽  
Vol 17 (3) ◽  
pp. 390
Author(s):  
TALITA CAMARGOS GOMES ◽  
DÉCIO KARAM
Keyword(s):  
Sorghum Bicolor ◽  
Sweet Sorghum ◽  
Block Design ◽  
Crop Management ◽  
Dry Mass ◽  
Grain Sorghum ◽  
Weed Species ◽  
Importance Value Index ◽  
Importance Value ◽  
Randomized Block Design

RESUMO: O conhecimento de uma comunidade infestante é necessário para se avaliar o nível de dano que esta pode causar na produtividade de qualquer cultura. Assim, o objetivo do estudo foi realizar levantamento fitossociológico exploratório de plantas daninhas em áreas com sorgo sacarino e granífero em função de densidades e espaçamentos de plantas de sorgo como forma de manejo cultural. O estudo foi conduzido em campo, com delineamento experimental de blocos casualizados, em esquema fatorial 2 x 2 x 2 com três repetições, sendo os tratamentos representados por duas cultivares de sorgo, BRS 506 e BR 330, semeadas em duas densidades (100.000, e 200.000 plantas ha-1) e dois espaçamentos (0,25 e 0,7 m) entre linhas. O levantamento das espécies infestantes foi realizado aos 56 dias após a emergência (DAE) do sorgo, pelo método do quadrado inventário. Observou-se que as diferenças em Índice de Valor de Importância para a mesma espécie daninha estão relacionadas à mudança na densidade e no espaçamento da cultura do sorgo.Palavras-chave: Sorghum bicolor, BRS 506, BR 330, fitossociologia, manejo cultural. POPULATION DYNAMICS OF WEED IN AREAS WITH SWEET SORGHUM AND GRAIN SORGHUM WITH DIFFERENT SPACINGS AND PLANTING DENSITIES  ABSTRACT – Knowing a weed community is important to estimate the level of damage that may cause to the productivity of any crop. Thus, the aim of the present study was to perform a phytosociological survey of weeds in areas with saccharine and grain sorghum considering the interaction between density and spacing of sorghum plants as a form of crop management. The study was conducted at field in a randomized block design with a 2 x 2 x 2 factorial scheme and three replications. Two sorghum cultivars (BRS 506 and BR 330) were seeded at two densities (100,000 and 200,000 plants ha-1) and two row spacings (0.25 and 0.7 m). The evaluation of the weed species was performed 56 days after emergence (DAE) of sorghum using the inventory square method. The dry mass of the weed species was determined. It was observed that the differences in the importance value index of the same weed species are related to changes in the density and spacing of sorghum.Keywords: Sorghum bicolor, BRS 506, BR 330, phytosociology, crop management.

scholarly journals Weed interference on growth and yield of transgenic maize

2014 ◽  
Vol 32 (3) ◽  
pp. 515-520 ◽  
Author(s):  
R.M. Faria ◽  
R.E. Barros ◽  
L.D. Tuffi Santos
Keyword(s):  
Dry Matter ◽  
Block Design ◽  
Dry Mass ◽  
Transgenic Maize ◽  
Growth And Yield ◽  
Dry Matter Accumulation ◽  
Weed Species ◽  
Bidens Pilosa ◽  
Commelina Benghalensis ◽  
Randomized Block Design

Plants kept under competition tend to modify their morphology to optimize the use of production factors. This study aimed to evaluate the effects of competition between transgenic maize and five weed species on the growth and yield of transgenic maize hybrid. The experiment used a randomized block design with four replicates in a factorial 5 x 2 + 6 scheme consisting of a combination of maize under competition with five weed species (Bidens pilosa, Commelina benghalensis, Brachiaria brizantha, Sorghum arundinaceum and Ipomoea triloba) in two weed densities (15 or 30 plants m-2) plus six treatments corresponding to maize and weed species without competition. All the means for dry matter accumulated by maize plants in the stem and leaf in the density of 15 plants m ² were higher than the means for plants in coexistence with 30 plants m-². Number of kernels, diameter and length of cob were not affected by competition with weeds. The weeds that most interfered with maize biomass production were S.arundinaceum and B.brizantha. Leaf dry mass accumulation was more sensitive than the production of stem. It was observed that maize was usually very competitive with weeds, and there was a strong decrease in dry matter accumulation of all the weeds in the study when in coexistence with the crop.

scholarly journals Period of Weed Interference in Guarana Crop

2019 ◽  
Vol 37 ◽  
Author(s):  
D.O.P. SOARES ◽  
S.M.F. ALBERTINO ◽  
F.C.P. SOUZA ◽  
A.F. SANTOS ◽  
J.F. SILVA
Keyword(s):  
Urban Areas ◽  
Block Design ◽  
Limiting Factor ◽  
Weed Species ◽  
Importance Value Index ◽  
Importance Value ◽  
Rural And Urban Areas ◽  
Weed Interference ◽  
Randomized Block Design ◽  
Four Blocks

ABSTRACT: Guarana is a plant native to the Amazon region that produces the fruit known as guarana. Guarana production is carried out by small farmers and is a source of income for thousands of people in rural and urban areas. The interference caused by the competition between weeds and guarana is an important limiting factor of its production. Despite its economic and social importance, there are few studies on the management of weeds in this species. Thus, this research aimed to study the effects of weed interference on guarana yield in different periods. This study was performed in Maués, AM, in the 2014 and 2015 seasons. The experimental design was a randomized block design with eight treatments and four blocks. Treatments consisted of a combination of four different periods of control or coexistence with weeds (March to May, June to August, September to November, and December to February). Weed community was composed of 23 weed species belonging to 12 botanical families, with Paspalum virgatum being the species with the highest importance value index (55.74%). Weed coexistence with guarana from June to August provided the lowest yields (156.16 kg ha-1 of grains) when compared to weed control in the same period (309.05 kg ha-1 of grains). Weed interference from June to August reduced guarana yield by 50%.

scholarly journals NITROGEN RATES ON GROWTH, YIELD AND NITRATE FOLIAR CONTENT OF ARUGULA

2021 ◽  
Vol 34 (2) ◽  
pp. 380-387
Author(s):  
PAULO HENRIQUE SOARES SILVA ◽  
ARTHUR BERNARDES CECÍLIO FILHO ◽  
ISAÍAS DOS SANTOS REIS ◽  
SÉRGIO MANUEL RUGELES REYES ◽  
MARA CRISTINA PÊSSOA DA CRUZ
Keyword(s):  
Block Design ◽  
Growth Yield ◽  
Dry Mass ◽  
Risk Level ◽  
Nitrate Content ◽  
Negative Effects ◽  
Growing Seasons ◽  
Randomized Block Design ◽  
Set Up ◽  
Leaf N

ABSTRACT Nitrogen is the second nutrient most demanded by arugula. However, the positive effect it has on yield can negatively impact the quality of this vegetable, with negative effects on human health. Two experiments (summer and autumn) were carried out to evaluate the effect of N rates (0, 50, 100, 150, 200 and 250 kg ha−1) on the arugula growth, yield and quality (nitrate content). Each experiment was set up in a randomized block design with four replications. Increasing rates of N reflected positively on leaf N content and thus, higher and desirable values of height, leaf number, leaf area and plant dry mass were obtained in both growing seasons. Consequently, the yield had significant increase, which N was maximized in summer (4.9 kg m−2) and autumn (2.6 kg m−2) and leaf N of 29.4 and 27.0 g kg−1, respectively, at rates of 250 and 213 kg ha−1 and both growing seasons. The higher rate the higher foliar nitrate content of arugula, in summer (2931.3 mg kg−1) and autumn (4218.4 mg kg−1). The foliar nitrate content in both crop season do not reach the risk level to human being heath.

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