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1
Maynard, Elizabeth T. "Effect of Light during Cultivation on Weed Emergence". HortScience 32, n. 3 (giugno 1997): 428F—429. http://dx.doi.org/10.21273/hortsci.32.3.428f.
Testo completoAbstract (sommario):
This experiment was conducted to determine whether light conditions during cultivation affect the number or species composition of emerging weeds. Plots were cultivated on 31 May 1996 under the following light conditions: 1) Ambient nighttime light (full moon) plus tractor headlights, 2) ambient nighttime light plus tractor headlights covered by transparent green film (green tractor lights), 3) ambient nighttime light with no tractor headlights, 4) ambient mid-day light. A fifth treatment was not cultivated at all, but was treated with glyphosate on 31 May to kill emerged plants. Results discussed below are based on weed densities determined 3 weeks after cultivation. Cultivated plots had more broadleaf weeds than uncultivated plots (119/m2 vs. 40/m2). Annual grass populations were the same in cultivated and uncultivated plots (20/m2). Common lambsquarters (Chenopodium album) and carpetweed (Mollugo verticillata) were the most common annual broadleaf weeds, representing more than 80% of the annual broadleaf population in cultivated plots. Light conditions during cultivation did not influence the total number of broadleaves, number of annual grasses, or total number of weeds emerging. Lambsquarters emerged in greater numbers after daytime or night cultivation using green tractor lights (48/m2) than after night cultivation using standard tractor headlights (32/m2). These results suggest no practical benefit to night cultivation for reducing overall weed density. A similar study in 1995 led to a similar conclusion. Although measurable effects of light conditions on weed emergence were observed in both years, the magnitude and consistency of the effects were not enough to suggest changes in cultivation practices without further research.
2
Yasin, Muhammad, Eva Rosenqvist e Christian Andreasen. "The Effect of Reduced Light Intensity on Grass Weeds". Weed Science 65, n. 5 (14 agosto 2017): 603–13. http://dx.doi.org/10.1017/wsc.2017.17.
Testo completoAbstract (sommario):
The effect of reduced light intensity on the growth and development of three common grass weeds, blackgrass, silky windgrass, and annual bluegrass, was studied. Two identical greenhouse experiments displaced in time were performed with six light levels aiming at 0%, 20%, 50%, 80%, 90%, and 95% shade corresponding to a mean daily light integral (DLI) of 12.4, 9.63, 7.13, 2.74, 0.95, and 0.69 mol m−2d−1in experiment 1 and 21.2, 18.0, 10.7, 3.71, 1.64, 1.20 mol m−2d−1in experiment 2. Climate screens of acrylic fabric were used to create the light levels. A DLI of 0.69 to 3.71 mol m−2d−1substantially reduced the plant height, the number of leaves, leaf chlorophyll content index, stomatal conductance, maximum photochemical efficiency of photosystem II, and dry matter of blackgrass. It also reduced plant height, the number of leaves, and dry matter and delayed flowering of windgrass and annual bluegrass. Annual bluegrass reacted most rapidly when light levels increased from the lowest levels by producing more leaves. DLI thresholds for blooming were estimated to be about 7.13 mol m−2d−1for windgrass and 1.64 mol m−2d−1for annual bluegrass. Annual bluegrass was able to bloom and sustain biomass even at a DLI of 1.64 mol m−2d−1. This ability may contribute to an explanation of why annual bluegrass is among the most common weed species in highly competitive and well-fertilized crops even though it is much smaller than the two other grass species.
3
MONDANI, Farzad, Farid GOLZARDI, Godarz AHMADVAND, Reza GHORBANI e Rooholla MORADI. "Influence of Weed Competition on Potato Growth, Production and Radiation Use Efficiency". Notulae Scientia Biologicae 3, n. 3 (25 agosto 2011): 42–52. http://dx.doi.org/10.15835/nsb336125.
Testo completoAbstract (sommario):
Weed management in potato production is one of the main cost and time consuming practices. Understanding the most effective time of weed control could reduce the costs and increase potato yield. Field study was conducted in the west region of Iran during 2006 to evaluate the effect of weeds damage in potato fields. Twelve treatments used consisted of six initial weed-free periods in which plots were kept free of weeds for 0, 10, 20, 30, 40 and 50 days after crop emergence (DAE), and then weeds were allowed to grow until harvest, and six initial weed-infested periods in which, weeds were allowed to grow for 0, 10, 20, 30, 40 and 50 DAE, then the plots were kept free of weeds until harvest. Experiment was arranged as a randomized complete block design with three replications. The results showed effect of weed competition on crop dry matter started about 40 DAE and about 90 DAE reached its maximum. The weeds competition decreased dry matter accumulation, leaf area index, crop growth rate, leaf area index duration, light absorption, light extinction coefficient and radiation use efficiency (RUE) of potato. Weeds reduced the potato yield 54.8 percent. The beginning and the end of the critical period of weed control in potato (CPWC) was based on 5% and 10% tuber yield loss. The onset of the CPWC ranged from 486 to 572 GDD, at 5% and 10% yield loss level corresponding to 11 and 19 days after crop emergence, respectively. The end of the CPWC varied from 1372 to 1164 GDD, at 5% and 10% yield loss level corresponding to 65 and 51 days after crop emergence, respectively. RUE in the weed infestation treatment in comparison to the weed free treatment, reduced 11.8 percent.
4
Nordby, Dawn E., Dustin L. Alderks e Emerson D. Nafziger. "Competitiveness with Weeds of Soybean Cultivars with Different Maturity and Canopy Width Characteristics". Weed Technology 21, n. 4 (dicembre 2007): 1082–88. http://dx.doi.org/10.1614/wt-06-190.1.
Testo completoAbstract (sommario):
Field studies were conducted in 2005 at five locations throughout Illinois to determine the effect of maturity date and canopy width characteristics of selected glyphosate-resistant soybean cultivars on competitive ability against weeds. Natural weed populations at all sites were allowed to compete with the soybean cultivars until the V1, V3, V5, or V7 growth stage and then removed with an application of glyphosate. Light-interception readings, weed control ratings, and soybean yield were all measured to compare cultivars. Cultivars of later maturities tended to withstand early season weed competition better and attained higher yields when weeds were removed at later timings than those of earlier maturity. Although canopy width differed moderately among cultivars in some cases, canopy width had no effect on the ability of soybeans to compete with weeds. Thus, choosing soybean cultivars of later maturity might provide more flexibility in weed management and might reduce losses due to weeds, but that benefit needs to be balanced with yield potential.
5
Lotz, L. A. P., M. J. Kropff e M. W. Groeneveld. "Modelling weed competition and yield losses to study the effect of omission of herbicides in winter wheat." Netherlands Journal of Agricultural Science 38, n. 4 (1 dicembre 1990): 711–18. http://dx.doi.org/10.18174/njas.v38i4.16559.
Testo completoAbstract (sommario):
Omission of application of various herbicides to winter wheat cv. Arminda, cv. Citadel, cv. Okapi, cv. Granada, cv. Sarino and cv. Tombola on clay and sandy soil in 1982-86 caused a significantly lower crop yield only when the densities of certain weed species were extremely high in spring. A dynamic model simulating the competition for light and water between broadleaved weeds and winter wheat was used to assess the observed small effects of weeds on yield in terms of the relative emergence time, physiological and morphological characteristics of weeds. Like the experiments, the simulations indicated that in the Netherlands weeds emerging in spring hardly affect crop yield. Weeds emerging in autumn, however, reduced crop yield considerably if they grew as tall as winter wheat (20% loss at a density of 100 plants/msuperscript 2). The results are discussed in relation to characteristics of crop rotation systems that include root and tuber crops. (Abstract retrieved from CAB Abstracts by CABI’s permission)
6
Gallagher, Robert S., e John Cardina. "The effect of light environment during tillage on the recruitment of various summer annuals". Weed Science 46, n. 2 (aprile 1998): 214–16. http://dx.doi.org/10.1017/s0043174500090445.
Testo completoAbstract (sommario):
Weed seeds can require an exposure to light for induction of germination. Conducting tillage operations at night and thus preventing the photoinduction of germination has been proposed as a means to reduce weed emergence in agricultural systems. This research was conducted to evaluate night tillage as a weed management option and to determine which tillage operations have the greatest effect on light-mediated recruitment. Weed emergence was evaluated after conducting factorial combinations of day and night moldboard plowing and disking in the springtime from 1992 through 1995. The light environment during disking generally had a slightly greater effect on emergence than the light environment during plowing. Emergence of pigweed species and giant foxtail was, at most, 30 to 55% higher following day vs. night disking. Emergence of other weeds was not affected by the light environment during tillage. We conclude that night tillage may not be a viable approach to weed management due to insufficient reductions in weed emergence associated with night tillage and the high degree of variability in the recruitment response to light conditions during tillage.
7
Buhler, Douglas D. "Effects of Tillage and Light Environment on Emergence of 13 Annual Weeds". Weed Technology 11, n. 3 (settembre 1997): 496–501. http://dx.doi.org/10.1017/s0890037x00045310.
Testo completoAbstract (sommario):
Seeds of many plant species require a brief exposure to light to induce germination. Modifying the light environment during soil tillage may alter weed emergence in agricultural systems. The objective of this research was to evaluate the effect of secondary tillage conducted during daylight and at night on the emergence of 13 summer annual weed species under the same soil and environmental conditions. Annual grass and large-seeded broadleaf species showed little response to light environment during tillage. However, emergence was often less when no tillage was conducted than with any tillage by light environment combination. Emergence of small-seeded broadleaf species often was lower when tillage was conducted during darkness than with tillage during the light. Reductions varied by experiment and species and ranged from 70% for common lambsquarters to less than 30% for Pennsylvania smartweed. Large variations in response also occurred within species.
8
Chen, Zhengqiang, e Zhaomin Ma. "A Review: The Survey of the Effects of Light on Weed Recognition". MATEC Web of Conferences 228 (2018): 04008. http://dx.doi.org/10.1051/matecconf/201822804008.
Testo completoAbstract (sommario):
Weeding is one of the important tasks in agricultural field management. With the development of society and information technology, automatic weeding has become a developing trend. The automatic recognition of weeds based visual is the important step. In this paper, the effects of lighting on green identification and weed identification algorithms are summarized. In order to improve the accuracy and stability of the identification of crops and weeds, some further worth problems in the study are also put forward. This will help further research on automatic weeding.
9
Everaarts, A. P. "Effects of competition with weeds on growth, development and yield of soyabeans." Netherlands Journal of Agricultural Science 40, n. 1 (1 marzo 1992): 91–107. http://dx.doi.org/10.18174/njas.v40i1.16531.
Testo completoAbstract (sommario):
Two field experiments were carried out in the inland Zanderij area of Suriname to study competition between soyabeans and weeds. The crop was kept weed-free or without weed control for increasing periods of time after sowing. An analysis of the growth and development of a crop with weed control and of a crop without weed control was obtained by making observations at the end of each period of time with or without weed control. Uncontrolled weed growth concentrated mainly between the rows. Competition with weeds reduced ground cover and LAI of the crop, leading to a lower weight and yield. Plant density was not affected, but weed competition reduced the number of branches, inflorescences, and pods per plant. Timing of flowering was not influenced. Competition for water was inferred and competition for light seemed likely. Competition for nutrients was weak. Weeding in the period of pod initiation, i.e. around 45-70 days after sowing, appeared to be essential to avoid competition with weeds. A period of around 4 weed-free weeks after sowing was necessary to avoid yield reduction or too much weed growth at harvest. (Abstract retrieved from CAB Abstracts by CABI’s permission)
10
Johnson, Mark S., e Steven A. Fennimore. "Weed and Crop Response to Colored Plastic Mulches in Strawberry Production". HortScience 40, n. 5 (agosto 2005): 1371–75. http://dx.doi.org/10.21273/hortsci.40.5.1371.
Testo completoAbstract (sommario):
The phase out of methyl bromide has forced strawberry (Fragaria ×ananassa Duchesne) growers to consider the use of cultural methods such as colored mulches to enhance weed control. Black plastic mulch controls most weeds; however, black mulch often does not warm the soil as well as clear mulch. Soil warming with clear mulch is desirable for early season markets, but clear mulch does not control weeds. Neither black nor clear mulches combine the ideal weed control and soil warming characteristics required. Seven colored mulches, as well as clear, black and no mulch were evaluated in California organic and conventional strawberries to identify mulch factors associated with weed control and soil warming. Laboratory and greenhouse experiments were also conducted to isolate the effects of light transmittance through mulch on weed germination and growth. The effect of mulch color on transmittance of photosynthetically active light (400 to 700 nm) through mulches was the key weed control factor, and was more important than the effect of mulch color effect on weed germination. Satisfactory weed control was provided by all mulches except clear, blue and red-brown laminated. Clear and black mulches provided the greatest soil warming in sunny and cloudy climatic conditions, respectively, although plants in clear mulched conventional production system plots produced the highest yield of marketable berries. Green and brown plastic mulches provided the best combinations of soil warming and weed control benefits at all trial locations.
11
Alptekin, Harun, Abdullah Ozkan, Ramazan Gurbuz e Muhittin Kulak. "Management of Weeds in Maize by Sequential or Individual Applications of Pre- and Post-Emergence Herbicides". Agriculture 13, n. 2 (10 febbraio 2023): 421. http://dx.doi.org/10.3390/agriculture13020421.
Testo completoAbstract (sommario):
Weeds impose serious problems in maize (corn) production, resulting in reduced crop yields and lower profits for farmers. The adverse effects of weeds have been attributed to the competition with maize plants for light, water, and nutrients, which can result in reduced growth and yield of the crop. In this context, effective weed management is important to minimize the negative impact of weeds on maize production. This can be achieved through a combination of cultural, mechanical, and chemical control methods. The use of pre-emergence and post-emergence herbicides as sequential or individual applications of these herbicides can be an effective way to manage weeds in maize. Two consecutive field experiments were conducted in 2019 and 2020 in order to determine the efficacy of sequential and individual applications of Dimethenamid-P + Terbuthylazine and Isoxaflutole + Thiencarbazone methyl + Cyprosulfamide as pre- emergence. On the other hand, Mesotrione + Nicosulfuron and Dicamba + Nicosulfuron were used as post-emergence herbicides. The effects of the herbicides were also assayed on corn yield and related parameters. In this regard, we designed the experiment in a randomized complete block design with four replications. Accordingly, the effect of the herbicides varied according to the active ingredients of the herbicide and the weed species. In addition, the effectiveness of herbicides varied according to the assessment times. The lowest effect was found on E. crus-galli, which was obtained from Mesotrione + Nicosulfuron (MN) (35%) plots. Other herbicides showed high efficacy (95–100%). Concerning values of both years, the highest cob length, cob diameter, 1000-grain weight, and plant height were obtained in weed-free control plots and the highest grain yield was obtained in the control plots with weed-free checks as 12.88 tons/ha and 12.37 tons/ha, respectively. The lowest corn grain yield was obtained in weedy control plots in both years. Our findings demonstrate that the combination of pre- and post- emergence herbicides in maize can be an effective way chemical weed control option.
12
Dentika, Pauline, Harry Ozier-Lafontaine e Laurent Penet. "Weeds as Pathogen Hosts and Disease Risk for Crops in the Wake of a Reduced Use of Herbicides: Evidence from Yam (Dioscorea alata) Fields and Colletotrichum Pathogens in the Tropics". Journal of Fungi 7, n. 4 (9 aprile 2021): 283. http://dx.doi.org/10.3390/jof7040283.
Testo completoAbstract (sommario):
The transition toward sustainable agriculture requires rethinking cropping systems in the light of less intensive and chemically reliant practices. Weed management is one of the target practices to evolve cropping systems with decreased impact on the environment. While softened management will lead to increased weeds/crops coexistence, it is of importance to assess the relative benefits and drawbacks of new practices. Among the potential drawbacks of weeds/crops coexistence, disease risk may increase if weeds are hosting pathogens. In this study, we assessed the potential of weeds for hosting pathogenic generalist fungi known to translate into disease in crops. We first describe prevalence in fields after harvest and relate prevalence to species characteristics and communities. Then, we directly test the idea that weeds serve as inoculums sources during cropping with a natural experiment. This study highlights variation in host skill among feral weeds for Colletotrichum species, including potential congeneric sub-specialization on different weeds within communities. Last, prevalence within fields was more correlated to focal crop inoculation rates compared to local weed load, but there was a significant correlation effect with prevalence on weeds in the vicinity of fields, suggesting that weeds are mediating disease levels at the local scale, too. Results pointed to the importance of weed host skill in disease risk yet open the door to the potential control of pathogens via targeted weed management.
13
Jensen, Peter Kryger. "Effect of light environment during soil disturbance on germination and emergence pattern of weeds". Annals of Applied Biology 127, n. 3 (dicembre 1995): 561–71. http://dx.doi.org/10.1111/j.1744-7348.1995.tb07612.x.
Testo completo
14
Madandoust, Mehdi, e Ahmad Ranjbar. "Effects of solarization on critical period of weed control in sesame (Sesamum indicum L.)". Outlook on Agriculture 46, n. 4 (dicembre 2017): 272–78. http://dx.doi.org/10.1177/0030727017744936.
Testo completoAbstract (sommario):
In order to determine the critical period of weed control in sesame, field studies were conducted during the 2014 and 2015 growing seasons in Estahban, Iran. The experiments were conducted based on factorial arrangement which involved a randomized complete block design with three replications. The first factor was conducted in two weed-infested and weed-free series until different phonological stages of sesame growth. These stages included a third pair true leaf initiation, first bud emergence, 50% opened flowers, and minor plants stop flowering, and the second factor was related to solarization which was achieved using light and dark polyethylene plastics and control. The results showed that the critical period of weed control was influenced by solarization so that solarization using light polyethylene plastic could severely shorten the critical period. Weed dry weight also gradually reduced, with increase in weed control, and the formation of first flower buds decreased significantly. Solarization did not have a great effect on the number of Convolvulus arvensis L. among the weeds, but its effect on one-year-old weeds was evident. Thus, weed infestation until the third pair true leaf initiation did not reduce sesame yield.
15
Živić, Jelica, Milić Vojinović, Ivica Stančić e Desimir Knežević. "WEED FLORA IN ALFAFLA CROPS". International Conference on Technics, Technologies and Education, ICTTE 2019 (2019): 452–56. http://dx.doi.org/10.15547/ictte.2019.07.014.
Testo completoAbstract (sommario):
Alfalfa is a perennial crop that is grown several years on the same surface and because of this there are specificities in the composition and structure of the weed community. This leads to difficulties in suppresses and reduction of pests, diseases and weeds at the yield of alfalfa. The basic harmful effect of weeds is reflected through the competitiveness of water, nutrients and light. Weeds generally have low nutritional value, unpleasant smell and taste, and also affect the quality of alfalfa seeds. The most common types of economy effective perennial weed are Cirsium arvense (L), Sorghum halapense (L.), Convolvulus arvensis (L.) and Cuscuta genus. All agro-technical measures, which enable good soil, quality sowing, as well as plant protection later, are the basic measures for the protection of alfalfa from long-lasting weed species. This paper is based on analysis of weeds flora in alfalfa crops in the Nis district. The presence of the fifteen most important types of weed plants was found in all nine analyzed areas of alfalfa crops. Among the weeds, most common are Agropyrum repens(L.), Amaranthus retroflexus(L.), Chenopodium hybridum(L.), Cuscuta sp.(L.), Sorghum halapense(L.).
16
Pavithra, M., e R. Poonguzhalan. "Weed flora of aerobic rice and their effect on growth, yield and nutrient uptake by rice Oryza sativa in the coastal region of Karaikal of Puducherry, India". Journal of Applied and Natural Science 10, n. 1 (1 marzo 2018): 397–402. http://dx.doi.org/10.31018/jans.v10i1.1637.
Testo completoAbstract (sommario):
A field experiment was conducted at farm lands of Pandit Jawaharlal Nehru College of Agriculture and Research Institute, Karaikal to know the weed floristic composition and their effect on growth, yield and nutrient uptake by aerobic rice (Oryza sativa). The results revealed that totally 29 species of weeds from 22 genera belonging to 17 families were noticed. Among them, four were grasses, six were sedges, and nineteen were broad leaved weeds. Of this 29 species, four were perennials, and the rest were annuals. During initial stages (30 DAS), sedges dominated (38.3%) whereas at later stages (60 DAS) broad leaved weeds dominated the aerobic rice fields (42.5%). Grasses were found to be comparatively less dominant at both the stages. Echinochloa colona Link. (28.1%) followed by E. cruss-galli (L.) Beauv. (6.1%) among the grasses; Cyperus difformis L. (19.8%) followed by C. iria L (9.9%) among the sedges and Ludwigia abyssinica (28.0%) among the broad leaved weeds, were the predominant weed species in aerobic rice cultivation. Weeds, when left unchecked, competed with rice for all resources like nutrients, space, light and soil moisture. The unweeded control recorded the maximum nutrient depletion by weeds (76.6, 6.4 and 106.8 Kg of N, P andK ha-1 ). Due to severe competition, weeds suppressed the growth of rice which resulted in lower growth and yield attributes leading to lower grain (333 kg ha-1 ) and straw yields (1903 kg ha-1 ).
17
Listyowati, Charisnalia, Didik Indradewa e Siti Nurul Rofiqo Irwan. "Study on Weeds Abundance on Rice Fields in Mycorrhizal Inoculation and Different Planting Methods". Caraka Tani: Journal of Sustainable Agriculture 37, n. 2 (25 giugno 2022): 259. http://dx.doi.org/10.20961/carakatani.v37i2.53131.
Testo completoAbstract (sommario):
<span lang="EN-US">The increasing demand for rice and the increasing population growth rate require sustainable rice production. Direct seeding of rice (DSR) combined with the use of arbuscular mycorrhizal fungi (AMF) is needed to achieve sustainable food production. This study aims to determine the effect of the planting method and mycorrhizal inoculation on the diversity, composition and dominance of weeds in a rice field for the sustainability of agricultural production. The research used a split-plot design with three replications. The main plot was the planting method consisting of on row, drum seeder and transplanting, while the subplot was mycorrhizal inoculation divided into with mycorrhizal inoculation and without mycorrhizal inoculation. The observed variables were <span>light</span><span> penetration, weeds population, weeds composition, weeds biomass, </span>summed dominance ratio<em> </em>and community coefficient. The results showed that there were 34 kinds of weeds consisting of 13 families and the dominant weed was annual weeds, most of which were broadleaf weeds. The dominant weed was <em>Alternanthera sessilis</em> (L.) R. Br. ex DC. (sessile joyweed). The planting methods affected the weed population in 24 days after sowing (DAS) and the composition of broadleaf weeds in 24 DAS but did not affect weed biomass. The AMF inoculation did not affect weed population, composition, or biomass. It is necessary to find mycorrhizal species that can affect weed growth.</span>
18
Nelson, Kelly A. "Glyphosate Application Timings in Twin- and Single-row Corn and Soybean Spacings". Weed Technology 21, n. 1 (marzo 2007): 186–90. http://dx.doi.org/10.1614/wt-05-073.1.
Testo completoAbstract (sommario):
Field research was conducted in 2002 and 2003 to determine the effect of twin- and single-row spacing and POST glyphosate application timing on light interception, weed control, and grain yield of glyphosate-resistant corn and soybean. Row spacing did not affect light interception measured 10 to 11 wk after planting. Corn grain yield in 2002 was 1.0 Mg/ha higher in single rows compared with twin rows when averaged over glyphosate timing, but was unaffected by row spacing in 2003. Soybean grain yield was similar in 19- and 38-cm single rows, and single-row grain yield was 0.2 to 0.4 Mg/ha higher than the twin-row spacing. Corn grain yields were similar to the weed-free control when glyphosate was applied to weeds 10 to 15 cm tall in 2002 and 10 cm tall in 2003. Soybean yield was maximized by application of glyphosate to weeds 15 to 30 cm tall in 2002 and 60 cm tall in 2003.
19
Blackshaw, Robert E., Louis J. Molnar, Duane F. Chevalier e C. Wayne Lindwall. "Factors affecting the operation of the weed-sensing Detectspray system". Weed Science 46, n. 1 (febbraio 1998): 127–31. http://dx.doi.org/10.1017/s0043174500090287.
Testo completoAbstract (sommario):
Field experiments were conducted for 3 yr to determine the effect of various biological and physical factors on the operation of the weed-sensing Detectspray system. Plant detection is achieved by sensors measuring differential reflectance of red and near-infrared wavelengths of light from green plants, crop residues, and soil. Weed detection was greatly reduced 70 to 80 min after sunrise and before sunset when operated at lat 50°N because of reduced solar irradiance. Tall, dense-standing crop stubble limited detection of small weeds at the soil surface. Weed detection varied with plant species. Canola with three to four leaves consistently was detected, but wheat or green foxtail usually required five to six leaves to be detected. Small weeds were detected if present at densities greater than 70 plants m−2. Growers and commercial applicators need to be aware of the limitations of the Detectspray system to use it effectively to control weeds with concurrent reductions in herbicide use.
20
Salikhov, Talgat, Sagyntay Elubaev, Marat Tynykulov, Gulzhanat Kapbassova e Anar Makhmutova. "The Effect of the Timing of Manure Application in Combination with Mineral Fertilizers and Planting Density on the Weediness of Potato Plantings". Scientific Horizons 24, n. 7 (29 dicembre 2021): 46–52. http://dx.doi.org/10.48077/scihor.24(7).2021.46-52.
Testo completoAbstract (sommario):
Potatoes are one of the most responsive crops for grooming techniques since in the period from seedlings before closing rows are easily suppressed by weeds that take away nutrients, water, light from it. The factor that causes high harm to potatoes is weed. By absorbing a large number of nutrients and moisture from the soil, weeds inhibit the growth and development of plants, reducing their potential productivity. The purpose of the study was to establish the effect of the timing of the introduction of bedding manure in conjunction with mineral fertilizers and planting density on the weediness of potato plantings. Studies were provided to identify the impact of the timing of bedding manure together with mineral fertilizers and planting density for weed planting potatoes. Experiments were laid by the systematic method with a tiered arrangement of variants in the experiment with a 3-fold repetition. We used cattle manure on straw bedding for autumn-winter harvesting. The following types of fertilizers were used: ammonium nitrate, double superphosphate, potassium chloride. Determination of the amount and biomass of weeds in potato plantings was carried out in the flowering phase and before harvesting. The application of manure was accompanied by an increase in the number and weight of weeds. Annual weeds predominated in potato plantings: Amaranthus retroflexus L., 1753 and Amaranthus blitoides S. Watson, 1877, Chenopodium album L. Chenopodium album L., 1753, Setaria P. Beauv, 1812 and Setaria viridis (L.) P. Beauv, 1812, Echinochloa crus-galli (L.) BEAUV., 1812 and others, perennials included Cirsium arvense (L.) SCOP. 1772 and Sonchus arvensis L., 1753, (Elytrigia repens (L.) DESV. ex NEVSKI, 1933 and others. Planting density also has a definite effect on the development of weeds. When manure was applied in autumn under the plow, the number of weeds increased in comparison with other options, where only mineral fertilizers were applied. The application of manure over frozen plow and in winter over snow leads to a slight decrease (2.3-2.5 pcs/m2) of weeds. The greatest number of weeds is observed during the spring application of manure for plowing the fall plow. Nevertheless, studies aimed at clarifying the composition and structure of weediness, the number and weight of weeds in potato plantings are of great practical importance for local agricultural producers. These data should contribute to the development of an effective weed control system and high yields of potatoes in the region
21
Ribeiro, Victor Hugo Vidal, Marcos Antônio Da Silveira Júnior, Gustavo Antônio Mendes Pereira, Evander Alves Ferreira, Enilson De Barros Silva e José Barbosa Dos Santos. "Total chlorophyll and nutrients content in bean plants and weeds in competition". Comunicata Scientiae 8, n. 2 (1 febbraio 2018): 307–15. http://dx.doi.org/10.14295/cs.v8i2.2173.
Testo completoAbstract (sommario):
Plants compete for several resources on soil, including water, light and nutrients which can affect crop yield and also weeds growth. Under the hypothesis that in different densities and weed communities, crops and weeds undergo changes in their nutritional contents of macro and micronutrients, the aim of this study was to quantify the nutritional contents of bean plants and weeds cultivated in increasing densities (0, 74, 147, 221 and 295 plants m-2) and the effect of the association of plants (isolated bean, bean + Urochloa plantaginea, bean + Bidens pilosa and bean + Urochloa plantaginea + Bidens pilosa). The contents of macro and micronutrients were evaluated. The increase in plant density promoted a decrease in the total chlorophyll content of bean plants and weeds, as well as a decrease in macronutrients (K and P) and micronutrients (Zn, Fe, Mn and Cu). In the arrangement where the greatest number of species were cultivated simultaneously and in increasing densities, a greater reduction in total chlorophyll content and in macro and micronutrient contents of the three species (crops and weeds) were observed.
22
Borger, Catherine P. D., Abul Hashem e Shahab Pathan. "Manipulating Crop Row Orientation to Suppress Weeds and Increase Crop Yield". Weed Science 58, n. 2 (giugno 2010): 174–78. http://dx.doi.org/10.1614/ws-09-094.1.
Testo completoAbstract (sommario):
Crop rows oriented at a right angle to sunlight direction (i.e., east–west within the winter cropping system in Western Australia) may suppress weed growth through greater shading of weeds in the interrow spaces. This was investigated in the districts of Merredin and Beverley, Western Australian (latitudes of 31° and 32°S) from 2002 to 2005 (four trials). Winter grain crops (wheat, barley, canola, lupines, and field peas) were sown in an east–west or north–south orientation. Within wheat and barley crops oriented east–west, weed biomass (averaged throughout all trials) was reduced by 51 and 37%, and grain yield increased by 24 and 26% (compared with crops oriented north–south). This reduction in weed biomass and increase in crop yield likely resulted from the increased light (photosynthetically active radiation) interception by crops oriented east–west (i.e., light interception by the crop canopy as opposed to the weed canopy was 28 and 18% greater in wheat and barley crops oriented east–west, compared with north–south crops). There was no consistent effect of crop row orientation in the canola, field pea, and lupine crops. It appears that manipulation of crop row orientation in wheat and barley is a useful weed-control technique that has few negative effects on the farming system (i.e., does not cost anything to implement and is more environmentally friendly than chemical weed control).
23
Norsworthy, Jason K., Brandon W. Schrage, Tom L. Barber e Lauren M. Schwartz. "Effect of Shading, Cultivar, and Application Timing on Cotton Tolerance to Glufosinate". Journal of Cotton Science 20, n. 3 (2016): 271–79. http://dx.doi.org/10.56454/kzvi4403.
Testo completoAbstract (sommario):
The increasing presence of glyphosate-resistant (GR) weeds in the Midsouth, and inconsistent crop injury and moisture dependence of residual herbicides has created a need for effective post-emergence options. Cotton cultivars with tolerance to glufosinate have been widely adopted by growers throughout the Midsouth because glufosinate provides an effective option for controlling GR weeds like Palmer amaranth (Amaranthus palmeri (S.) Wats.]. The objective of this study was to determine if differences exist in tolerance of PhytoGen® and Liberty Link® cultivars to glufosinate applied at different growth stages in the presence and absence of low-light conditions. At two weeks after cotton emergence (WAE), tolerance to glufosinate differed by cultivar, although some injury was observed on Liberty Link cotton. Injury was often greatest when applied at the one-leaf stage to PhytoGen® cultivars, but by four to five weeks after treatment, all cultivars showed similar potential to recover. In general, cotton plants that were shaded three days prior to applying glufosinate were injured to a greater extent than non-shaded plants. Similarly, seed cotton yields were reduced in shaded plots by 72 and 76 g m-1 of row in 2012 and 2013, respectively. This research indicates that there is greater risk for early-season injury from glufosinate if applied to young cotton experiencing prolonged cloudy conditions prior to application; albeit, this injury does not translate into seed cotton yield loss for the three cultivars evaluated, compared to an untreated control. Hence, it is recommended that growers make timely applications of glufosinate to optimize weed control, even when conditions have been less than ideal for cotton growth prior to application.
24
Wayman, Sandra, Craig Cogger, Chris Benedict, Doug Collins, Ian Burke e Andy Bary. "Cover Crop Effects on Light, Nitrogen, and Weeds in Organic Reduced Tillage". Agroecology and Sustainable Food Systems 39, n. 6 (23 febbraio 2015): 647–65. http://dx.doi.org/10.1080/21683565.2015.1018398.
Testo completo
25
Zaefarian, Faezeh, Zahara Shakibafar, Mohammad Rezvani e Hamid SALEHIAN. "Effect of cover crops on maize-velvet leaf competition: leaf area density and light interception". Acta agriculturae Slovenica 107, n. 2 (26 ottobre 2016): 409. http://dx.doi.org/10.14720/aas.2016.107.2.13.
Testo completoAbstract (sommario):
<p>Cover crops influence on canopy structure and light interception of maize (<em>Zea mays</em> L.) and velvetleaf (<em>Abutilon theophrasti</em> Medik), was studied in a field experiment. Treatments included planting of bean (<em>Phaseolus vulgaris</em> L.), soybean (<em>Glycine max </em>(L.) Merr.) and berseem clover (<em>Trifolium alexandrium</em> L.) as cover crops at the same date and 21 days after maize. Sole cropping of maize under weed- free and weedy conditions were also included in this experiment. All tested cover crops significantly reduced leaf area density and height of velvetleaf up to 50 %, while maize leaf area density increased in the presence of cover crops. Among cover crops, bean and soybean were the most effective in reducing velvetleaf leaf area density and height. Bean and soybean also strongly reduced absorbed light by velvetleaf by up to 80 % compared to clover. Maize grain yields were significantly influenced by cover crops planting in the inter row space. Compared to weeds free plots, only treatment with soybean as a cover crop resulted in similar maize grain yields, while maize intercropping with bean and clover significantly reduced maize yields. Delayed planting of cover crops, 21 day after maize, increased maize grain yield compared to cover crops and maize planting at the same time.</p>
26
Sharma, Neelam, Lokender Singh, S. Joshi e Rajesh Manhas. "Dominance, diversity and species composition of the weeds of rice crop in Doon Valley". Journal of Non-Timber Forest Products 14, n. 1 (1 marzo 2007): 63–69. http://dx.doi.org/10.54207/bsmps2000-2007-w0412d.
Testo completoAbstract (sommario):
Weeds have a direct effect on crop yields when they compete with the crop for nutrients, moisture and light. It is found infested with a variety of ways, which compete with the crop and often cause losses in grain yield ranging from 20-30%. During this study dominance, diversity and species composition of the weeds of Rice field in Doon Valley was studied. The study was conducted in the various Villages viz. Babugarh, Doctorganj and Bawanpur of the Vikasnagar block of Doon Valley in the month of August and September. A total of 24 weeds of rice fields were recorded in the selected sites. Lindernia anagallis, Cyperus iria and Echinochloa colona are the dominant weed species in the month of August, with the heighest IVI values (73.36, 57.69 and 67.45) in Babugarh, Doctorganj and Bawanpur respectively. Meanwhile, in September the highest IVI values (65.84, 53.66 and 94.56) were reported for weed species Caesulia axillaris, Cyperus difformis and Fimbristylis miliacea for the selected villages of Vikasnagar block of the Valley. Maximum diversity 2.54 was reported in the village Doctorganj during the month of September.
27
Scavo, Aurelio. "Allelopathic effects of Cynara cardunculus L. extracts". Bullettin of the Gioenia Academy of Natural Sciences of Catania 53, n. 383 (17 novembre 2020): MISC4—MISC5. http://dx.doi.org/10.35352/gioenia.v53i383.91.
Testo completoAbstract (sommario):
Weeds are recognized as the most important biotic factor affecting yields in agroecosystems. The negative effects derived from the irrational use of herbicides have led to an increasing interest to eco-friendly practices for weed control, including the manipulation of allelopathic mechanisms. The present study aims to explore the potential use of Cynara cardunculus L. leaf extracts for the biological control of weeds and pathogen microorganisms. In a first trial, the allelopathic effects of its leaf aqueous extracts were demonstrated on seed germination of six common weeds. Secondly, the set-up of the most efficient extraction method of its allelochemicals in terms of costs, yields and inhibitory activity was realized, selecting dried leaves as the best plant material and ethanol and ethyl acetate as the best solvents. Moreover, new C. cardunculus allelochemicals (cynaratriol, desacylcynaropicrin, 11,13-dihydro-desacylcynaropicrin and pinoresinol) were purified. Third, the effect of genotype, harvest time and light stress (by plant shading) was evaluated on the phytotoxicity, quantity and composition of sesquiterpene lactones in C. cardunculus leaf extracts through a new UHPLC-MS/MS analysis method. Wild and cultivated cardoon showed the highest concentrations, while spring was the best harvest time. Moreover, light stress stimulated the synthesis of these allelochemicals. In a second trial, the effects resulting from 3-years cultivation, in two different areas, with globe artichoke, cultivated and wild cardoon were studied on the quali/quantitative composition of the weed soil seed bank and on soil eubacterial communities. In both areas, C. cardunculus reduced the weed seed bank size compared to controls. Nevertheless, the presence of cultivated cardoon had a negative influence towards Bacillus subtilis and a positive one on Pseudomonas putida and Azospirillum brasilense. Lastly, cultivated cardoon leaf extracts were assessed in vitro for the control of several microorganisms of agriculture and food interest. All the extracts showed an important antimicrobial activity, especially when using ethanol as extracting solvent.
28
Singh, Kuldeep, Samunder Singh e R. K. Pannu. "Temperature, pH and light effect on germination and growth behavior of grassy weeds of direct-seeded rice". Indian Journal of Weed Science 52, n. 1 (2020): 21. http://dx.doi.org/10.5958/0974-8164.2020.00003.9.
Testo completo
29
Ohadi, Sara, Hamid R. Mashhadi e Reza Tavakol-Afshari. "Seasonal Changes in Germination Responses of Seeds of the Winter Annual Weed Littleseed Canarygrass (Phalaris minor) to Light". Weed Science 57, n. 6 (dicembre 2009): 613–19. http://dx.doi.org/10.1614/ws-09-084.1.
Testo completoAbstract (sommario):
Photocontrol of weeds requires knowledge about the response of weeds to light and its changes over time. Thus, littleseed canarygrass germination, as an important weed in winter crops, in response to the light environment was evaluated in seeds retrieved from different burial (10, 20, and 40 cm, under irrigated or nonirrigated conditions) or storage (room temperature 25 C and cold 3 C) conditions for 1 yr. Seeds buried in the soil showed a cyclical germination behavior when tested at 20 C, with high germination percentages (68%) occurring in August, October, and December and low percentages (12%) in February and April, with another late germination in June. Germination percentages were mostly higher for seeds incubated in light than in darkness and seeds were more likely to positively respond to light in June than at the other retrieval dates, with differences as great as 60% having been observed under irrigated conditions and at depths of 20 and 40 cm. The most outstanding effect of light as a germination stimulus was observed for seeds stored at room temperature where germination in light was always 20 to 35% higher than that in darkness. The viability of seeds did not change over time in seeds kept at room or cold temperature. However, the proportion of surviving seeds was reduced by 35 to 65% when buried in the soil. Littleseed canarygrass seeds tended to survive more when buried 40 cm deep and the differences between irrigated and nonirrigated conditions were only detectable at 10 cm deep, with higher seed mortalities under irrigated conditions. Information gained in this study would be useful in developing weed control programs for this species.
30
Patterson, David T. "Effects of Environmental Stress on Weed/Crop Interactions". Weed Science 43, n. 3 (settembre 1995): 483–90. http://dx.doi.org/10.1017/s0043174500081510.
Testo completoAbstract (sommario):
All environmental factors that influence plant growth potentially can affect the ability of weeds and crops to exploit the environmental resources for which plants compete. Stressful levels of environmental factors such as temperature, light, and water and nutrient availability influence weed/crop interactions directly and also may interfere with (or enhance) weed control. Weed and crop species differing in photosynthetic pathway (C3vs C4) are likely to respond differently to many of these factors. Long-term changes in the atmospheric concentrations of CO2and other radiatively-active “greenhouse gases” may exert direct physiological and indirect climatic effects on weed/crop interactions and influence weed management strategies. This review focuses on the effects of temperature, light, soil nutrients, water stress, and CO2concentration on weed/crop interactions with consideration of the potential impact of climate change.
31
Ronay, Inbal, Jhonathan E. Ephrath, Hanan Eizenberg, Dan G. Blumberg e Shimrit Maman. "Hyperspectral Reflectance and Indices for Characterizing the Dynamics of Crop–Weed Competition for Water". Remote Sensing 13, n. 3 (1 febbraio 2021): 513. http://dx.doi.org/10.3390/rs13030513.
Testo completoAbstract (sommario):
Understanding the spectral characteristics of crops in response to stress caused by weeds is a basic step in improving the precision of agricultural technologies that manage weeds in the field. This research focused on the competition between corn (Zea mays) and redroot pigweed (Amaranthus retroflexus), a common weed that strongly reduces corn yield. The aim of this research was to characterize the physiological changes that occur in corn during early growth because of crop–weed competition and to examine the ability to detect the effect of competition through hyperspectral measurements. A greenhouse experiment was conducted, and corn plants were examined during early growth, with and without weed competition. Hyperspectral measurements were combined with physiological measurements to examine the reflectance and photosynthetic activity of corn. Changes were expected to appear mainly in the short-wave infrared region (SWIR) due to competition for water. Relative water content (RWC), chlorophyll content, photosynthetic rate, and stomatal conductance were reduced in the presence of weeds, and intercellular CO2 levels increased. Deeper SWIR light absorption occurred in the weed treatment as expected, accompanied by spectral changes in the visible (VIS) and near infrared (NIR) ranges. The results highlight the potential of using spectral measurements as an indicator of competition for water.
32
Milberg, Per, e Lars Andersson. "Seasonal variation in dormancy and light sensitivity in buried seeds of eight annual weed species". Canadian Journal of Botany 75, n. 11 (1 novembre 1997): 1998–2004. http://dx.doi.org/10.1139/b97-911.
Testo completoAbstract (sommario):
We recorded germination in three different light environments (light, dark, and after a short light exposure) in eight annual weed species. Seeds were buried outdoors at the end of November 1994 and exhumed monthly from March 1995 to April 1996. All species exhibited substantial seasonal changes in dormancy level, and the patterns suggest that seeds of Papaver rhoeas germinate strictly in the autumn; Capsella bursa-pastoris, Descurainia sophia, Spergula arvensis, and Urtica urens mainly in the autumn; Chenopodium suecicum strictly in the spring; and Matricaria perforata mainly in the spring. Lapsana communis showed inconsistent dormancy changes over the year. All species had acquired a light requirement for germination after being in the soil, and in many cases the short light exposure (1050 μmol∙m−2) was enough to fulfil this requirement. The demonstrated seasonal changes in light sensitivity in several of the species will have to be taken into account in attempts to photocontrol weeds. By using the short-light treatment, we were able to detect seasonal dormancy changes that would not have been obvious by testing for germination in only light and darkness. Hence, light is not a simple dichotomous factor in its effect on germination. Key words: dormancy, germination, light, seed, Sweden, weed.
33
D, Kavitha. "ALLELOPATHIC POTENTIAL OF CYPERUS ROTUNDUS L. AND CYNODAN DACTYLON L. ON GERMINATION AND GROWTH RESPONSES OF SOME RICE CULTIVARS". Kongunadu Research Journal 2, n. 2 (30 dicembre 2015): 118–22. http://dx.doi.org/10.26524/krj107.
Testo completoAbstract (sommario):
Weeds are enemies to the crop plants and have harmful effects on agricultural crops due to several factors such as competition for space, light and nutrients and allelopathy. In the present study,various concentrations (0,5,10,15,20 and 25%) of whole plant aqueous extractsof weeds, Cyperus rotundusL.( Purple nut sedge) and Cynodan dactylon(L.) Pers. (Bermuda grass) were tested for assessing their allelopathic potential on seed germination and seedling growth of some rice (Oryza sativa L.) cultivars i.e.ADT-36,BPT5204 and IR-20 using pot culture experiments. The experimental results revealed that all the concentrations of both the weed extracts had inhibition on germination percentage, seedling length, number of,dry weight and chlorophyll contents of 15 day old seedlings of all the three rice cultivars and the inhibitory effect of the extracts was concentration dependent. However, at 5% of C. rotundus and10% of C. dactylon extracts did notaffect seed germination of IR-20 . Among the rice cultivars,the higher degree of growth inhibition was observed in ADT-36followed by BPT-5204 and IR-20 . The weed C.rotundusexhibited more intense on growth suppression of rice cultivars thanC.dactylon.
34
Brainard, D. C., e R. R. Bellinder. "Weed suppression in a broccoli–winter rye intercropping system". Weed Science 52, n. 2 (aprile 2004): 281–90. http://dx.doi.org/10.1614/ws-03-031r.
Testo completoAbstract (sommario):
Interseeded cover crops have the potential to maintain and improve soil quality, reduce the incidence of insect pests, and suppress weeds in vegetable production systems. However, the successful use of interseeded cover crops has been limited by their tendency to either inadequately suppress weeds or suppress both weeds and the crop. We hypothesized that in irrigated broccoli production, winter rye could suppress annual weeds through rapid emergence and shading, without adversely affecting the taller transplanted broccoli crop. In field experiments conducted in New York from 1999–2001, broccoli was cultivated at 0, 10, or 10 and 20 d after broccoli transplanting (DAT), with or without rye at the final cultivation. Rye interseeded at 0 DAT suppressed weeds and improved yields relative to unweeded controls but resulted in broccoli yield losses relative to weed-free controls in 2 of 3 years. Rye seeded at either 10 or 20 DAT did not reduce broccoli yields but had little effect on weeds for a given level of cultivation and resulted in Powell amaranth seed production of up to 28,000 seeds m−2. Rye interseeded at 0 DAT reduced light availability to weeds in 2000 but not in 2001 when Powell amaranth avoided shading from rye through rapid emergence and vertical growth. In greenhouse pot experiments, low temperatures for 7 d after seeding delayed the emergence of Powell amaranth by 3 d relative to rye and increased the suppression of Powell amaranth by rye from 61 to 85%. Our results suggest that winter rye may be more successfully integrated into broccoli production (1) when sown at higher densities, (2) in locations or seasons (e.g., spring) with lower initial temperatures, and (3) in combination with other weed management tools.
35
Dhaliwal, Salwinder Singh, Sandeep Sharma, Arvind Kumar Shukla, Vivek Sharma, Makhan Singh Bhullar, Tarundeep Kaur Dhaliwal, Mohammed Alorabi, Saqer S. Alotaibi, Ahmed Gaber e Akbar Hossain. "Removal of Biomass and Nutrients by Weeds and Direct-Seeded Rice under Conservation Agriculture in Light-Textured Soils of North-Western India". Plants 10, n. 11 (11 novembre 2021): 2431. http://dx.doi.org/10.3390/plants10112431.
Testo completoAbstract (sommario):
The escalating scarcity of irrigation water, transplantation of rice on light-textured soils and labour cost acted as major drivers for the transition towards direct-seeded rice (DSR) cultivation from the conventionally flooded transplanting system. Despite these advantages, DSR is a challenge in light texture soil due to heavy weed infestation and a slight decline in crop yield. The weeds compete for nutrients and have an adverse effect on the growth and yield of crops. Hence, to assess the removal of macro and micronutrients by weeds and direct-seeded rice, a field experiment was carried out on sandy loam soil for two consecutive Kharif seasons (2018 and 2019). Three treatments from rice, namely: DSR under zero tillage (DSR-ZT), DSR under conventional tillage (DSR-CT) and DSR under reduced tillage (DSR-RT) were taken as main plots with three tillage treatments in wheat, namely: Conventional tillage without rice straw (CTW-R), Zero tillage without rice straw (ZTW-R) and Zero tillage with straw as mulch using Happy Seeder (ZTW+R) as subplots, replicated thrice. Among the rice establishment methods, DSR-RT showed an edge in terms of rice grain and straw yield (6.18 and 8.14 Mg ha−1, respectively) as well as macro- and micronutrient uptake by rice. Under management practices, ZTW+R proved as an efficient strategy in terms of yield and nutrient uptake by crops. The contribution of weeds towards biomass production was maximum under the ZTW-R (9.44%) treatment followed by DSR-ZT (7.72%). The nutrient budgeting showed that macro- and micronutrient removal by weeds was minimum under reduced tillage (24.51 and 50.35%, respectively), whereas it was 21.88 and 44.87% when wheat was grown under conventional tillage without rice straw. In overall, the research study concluded that weeds on an average remove 25.65 % macronutrients (N, P, K) and 51.47% of micronutrients (Zn, Cu, Fe and Mn) in DSR under rice-wheat cropping system.
36
Chaudhary, Amit, Bishnu Bilash Adhikari e Jiban Shrestha. "Effect of weed species on drought tolerant rice genotypes at Sundarbazar, Lamjung, Nepal". Open Agriculture 4, n. 1 (8 marzo 2019): 65–78. http://dx.doi.org/10.1515/opag-2019-0006.
Testo completoAbstract (sommario):
Abstract Weeds compete with rice for water, nutrients, space and light. The effect of weeds on productivity of rice genotypes were studied at research field of Institute of Agriculture and Animal Science, Lamjung Campus, Lamjung, Nepal in 2016. Eight rice genotypes (IR-87684- 18-1-2-3, IR-83388-3-3-140-4, IR-8839-39-1-6-4, IR-87759-7- 1-2-3, IR-88966-22-1-1-1, IR-88839-3-1-2-2, IR-88869-2-2-2-2, and Sukhadhan-3) and two weed management practices (Weeded condition and non weeded condition) were studied in randomized complete block design (RCBD) with three replications. Results showed that weeding operation significantly increased the growth traits and final yield of rice genotypes. Non-significant results among tested genotypes were obtained for grain yield and straw yield however the maximum grain yield (3.68 t ha-1) and straw yield (5.99 t ha-1) were found in IR-88839- 39-1-6-4 which might be due to highest test grain weight (30.64 g), tallest plant height (105.7m) and lower sterility percentage (21.84%). Similarly, the relative grain yield loss due to weed infestation was 41.8%. The highest grain yield (3.99 t ha-1) and straw yield (6.90 t ha-1) was found in weeded plots compared to non-weeded plots (2.321 t ha-1 and 6.43 t ha-1, respectively). Among weed species, Rotala indica was found most dominant (1091 m-2) and proportion 18%) followed by Eriocaulon cinereum (245.83 m-2 and 12%). Interaction effect between variety and weed population showed non-significant results for all growth and yield attributes. The plots having highest number of weed population showed greater loss of rice yield. Thus this study suggests that weeding should be carried out to achieve higher rice production.
37
Tsvei, Ya, R. Ivanina e Yu Dubovyi. "Ecological controlling weed abundance in winter wheat crops". Karantin i zahist roslin, n. 1 (19 marzo 2020): 16–19. http://dx.doi.org/10.36495/2312-0614.2020.01.16-19.
Testo completoAbstract (sommario):
Goal. To study the effectiveness of fertilizers and crop rotation factor in controlling weed abundance in winter wheat crops.
Methods. Long-term field and analytical.
Results. Research data on the effectiveness of fertilizers and legumes predecessors in controlling weed abundance in winter wheat crops are presented. It has been established that the basis of weeding of winter wheat crops in the spring tillage phase was one- and dicotyledonous species, at the time of harvest — mostly by mass dicotyledonous. In the composition of the weeds, the largest competition for winter wheat crops for light and nutrients was created by Chenopodium album — 3.4—4.3 g/m2, Capsella bursa-pastoris L. — 0.6—4.0, Spergula vulgaris — 0.3—2.9, Fallopia convolvulus — 1.0—1.1 g/ m2. The use of mineral fertilizers significantly reduced the number of weeds in winter wheat crops at the beginning of the growing season and their mass at the time of harvest. Legume predecessors had not significant effect on the dynamics of weed development in winter wheat agrocenosis.
Conclusions. The application of mineral fertilizers has been identified as an effective measure todecreaseweeds abundance and their mass in winter wheat crops. At the fertilizer doses N60Р60К60 the number of weeds in the spring tillage phase decreased by 6.3—6.5 times as compared to the control without fertilizers, and the mass of weeds at the time of harvest — by 2.6—3.0 times. Under the clover predecessor, the mass of dicotyledonous weeds at the time of harvest compared to the spring vetch was slightly higher with the predominance of Capsella bursa-pastoris L. — 2.5 g/m2 and Chenopodium album — 2.3 g/m2. Increasing the nitrogen dose for winter wheat from 60 to 90 kg/ha only in the clover rotation chain slightly increased the weed mass at the time of harvest. The total weeds mass in comparison with the nitrogen dose of 60 kg/ha increased by 2.7 g/m2.
38
Biramahire, Bienvenu, Kwame Sarpong Appiah, Seishu Tojo, Yoshiharu Fujii e Tadashi Chosa. "Influence of Mowing and Trampling on the Allelopathy and Weed Suppression Potential of Digitaria ciliaris and Cyperus microiria". Sustainability 14, n. 24 (13 dicembre 2022): 16665. http://dx.doi.org/10.3390/su142416665.
Testo completoAbstract (sommario):
A long-term, sustainable solution to weed infestation is extremely desirable because weeds have the potential to reduce crop productivity and the aesthetic appeal of the environment. In this study, the impacts of mowing and varying degrees of trampling pressure on the suppression of weeds, alongside wound-induced changes in the allelopathic potential, of the rhizosphere soil and the root exudates of southern crabgrass (Digitaria ciliaris) and Asian flatsedge (Cyperus microiria) were evaluated under both field and greenhouse conditions. The field study results showed that all trampling treatments induced the relative suppression of weed growth. Grass weeds showed higher resistance to trampling than broad-leaved weeds. However, laboratory bioassays showed that light trampling caused a significant increase in the growth-inhibitory effects of southern crabgrass rhizosphere soil on lettuce. Moreover, mowing (9.11% of control) and trampling (16.4% of control) resulted in a marginal increase in the growth-inhibitory effects of root exudates released from southern crabgrass. Furthermore, the growth-inhibitory activities of the Asian flatsedge rhizosphere soil were significantly reduced after heavy trampling pressure. Moreover, mowing and trampling resulted in marginal reductions in the growth-inhibitory activities of root exudates released from Asian flatsedge against lettuce (i.e., 18.7% and 28.5%, respectively). In general, mowing and varying degrees of trampling induced contrasting and integrated impacts on weed suppression as well as the allelopathic potential of both southern crabgrass and Asian flatsedge.
39
Everaarts, A. P. "Effects of competition with weeds on growth, development and yield of groundnuts." Netherlands Journal of Agricultural Science 40, n. 1 (1 marzo 1992): 73–90. http://dx.doi.org/10.18174/njas.v40i1.16530.
Testo completoAbstract (sommario):
Competition between weeds and groundnuts was studied in two field experiments in the inland Zanderij area of Suriname. The crop was kept weed-free or without weed control for increasing periods of time after planting. Observations made at the end of each period with or without weed control provided an analysis of the growth of a crop with weed control and of a crop without weed control. Uncontrolled weed growth was concentrated between the rows. Competition with weeds reduced ground cover and LAI of the crop. DM accumulation was affected, resulting in lower yields. Plant density and number of branches per plant were not influenced. Weed competition increased stem length and reduced the number of leaves and pods per plant. Timing of flowering was not influenced. Competition for nutrients was absent, but there was competition for light and water. About 15 weed-free days after planting were sufficient to prevent yield losses. Yield losses were due to a reduction in number of pods per plant. Competition should especially be prevented in the period when the number of pods per plant is established, i.e. around 35-60 days after planting. (Abstract retrieved from CAB Abstracts by CABI’s permission)
40
Fagundes Marques, Ricardo, Guilherme Sasso Ferreira Souza, Maria Renata Rocha Pereira, Sidnei Roberto de Marchi e Dagoberto Martins. "Sowing depth and light intensity in the emergence and development of monocotyledonous weeds". Bioscience Journal 38 (23 settembre 2022): e38083. http://dx.doi.org/10.14393/bj-v38n0a2022-60820.
Testo completoAbstract (sommario):
This study aimed to evaluate the effects of different sowing depths and light intensities on the emergence and development of the monocot weed species, Urochloa decumbens and Cenchrus echinatus, under field conditions. Each species constituted an experiment, and the experimental design was completely randomized with four replicates. The treatments were arranged in a 6 x 4 factorial scheme, with six sowing depths (0.5, 1.0, 2.0, 4.0, 8.0, and 12.0 cm) associated with four solar radiation intensities (100%, 70%, 50%, and 30%) obtained through the use of shading screens. Seedling emergence capacity was evaluated daily to obtain the emergence percentage and speed index. Plant height, floral induction time, and plant dry matter at flowering were measured. Even when subjected to different solar radiation intensities, U. decumbens and C. echinatus seedlings emerged at all the sowing depths. Sowing between 2.0- and 4.0-cm depths favored the emergence of seedlings of U. decumbens and C. echinatus. However, sowing at 12-cm depth reduced the emergence of both species regardless of the solar radiation intensity. Urichloa decumbens plants grown under conditions of greater shading showed the lowest values of height and dry matter accumulation during flowering. High levels of shading facilitated only the etiolation of C. echinatus plants. Increased shading flowering time in both species compared to full sunlight.
41
Hassannejad, S., e A. R. Mobli. "Effects of Some Cover Crops on Light Extinction and Weed Coverage in Sunflower Field". Cercetari Agronomice in Moldova 47, n. 2 (8 luglio 2014): 29–40. http://dx.doi.org/10.2478/cerce-2014-0014.
Testo completoAbstract (sommario):
Abstract In order to evaluate the effects of some cover crops on extinction coefficient and weed cover percentage in sunflower, a field experiment was conducted based on a randomized complete block design with nine treatments and three replicates at the Agricultural Research Station, Tabriz University of Iran, during growing season 2012-2013. Treatments were triticale, hairy vetch, rapeseed, triticale + hairy vetch, triticale + rapeseed, hairy vetch + rapeseed, application of trifluralin herbicide, and controls (weed infested and weed free without planting cover crop). Result indicated than once established, living mulches can rapidly occupy the open space between the rows of the main crop and use the light that would otherwise be available to weeds. In the all cover crops treatments, the light extinction coefficient was increased and weed cover percentage was reduced. Highest reduction in total weed species was observed in hairy vetch + rapeseed and triticale + rapeseed cover crop 61.92% and 61.43 %, respectively, compared to weed infested, so this treatment was better than trifluralin application. It concluded that cover crops could be considered as integrated strategies for weed sustainable management.
42
Kural, Leyla, e Reyyan Yergin Özkan. "Allelopathic potential of white cabbage on some plants". Plant, Soil and Environment 66, No. 11 (2 novembre 2020): 559–63. http://dx.doi.org/10.17221/386/2020-pse.
Testo completoAbstract (sommario):
The aim of this study carried out in 2017–2018 was to determine the effect of white cabbage (Brassica oleracea L.), which is known to have an allelopathic effect on the germination of some weed and cultural crops seeds. In addition to weeds, Amaranthus retroflexus L., Chenopodium album L. and Solanum nigrum L., cultural plants such as Zea mays L., Beta vulgaris L., were used in this study. It has been shown that the seed germination rate was decreased by the increased concentration of white cabbage post-harvest leaves extractions, which were made with different concentrations of aqueous and methanol extracts (30, 40, and 50%). The methanol extract was found to be more effective in germination. According to these results, S. nigrum and Z. mays seeds were less affected than A. retroflexus, C. album and B. vulgaris seeds. In the light of these data, it is observed that extracts obtained from white cabbage can be effective on some weeds; however, it was concluded that in order to reach more definite conclusions, studies on the subject should be increased, and similar studies should be continued under greenhouse or field conditions.
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Albrecht, Alfredo Junior Paiola, Arthur Arrobas Martins Barroso, Henrique Fabrício Placido, André Felipe Moreira Silva, Leandro Paiola Albrecht, Fábio Henrique Krenchinski, Ricardo Victoria Filho e Luisa Carolina Baccin. "Factors influencing the germination and emergence of tall windmill grass (Chloris polydactyla) and swollen fingergrass (Chloris barbata)". MAY 2020, n. 14(05):2020 (20 maggio 2020): 795–801. http://dx.doi.org/10.21475/ajcs.20.14.05.p2243.
Testo completoAbstract (sommario):
This study characterized the germination of seeds of Chloris polydactyla (synonymy Chloris elata) and Chloris barbata at varying temperature, luminosity, soil texture and cover. The first experiment WAS conducted in laboratory to determine the temperature and light effects on germination of these species. The experimental design was a 2x7 factorial, where 2 represents the absence/presence of light and 7 temperatures 15, 20, 25, 30, 35, 40 and 45°C. The second experiment was conducted in greenhouse to determine effect of edaphic factors on seedling emergence, in a 3x6 factorial arrangement, consisting of 3 soil textures (sandy, medium and clayey) and 6 sowing depths (0, 1, 2, 4, 6 and 8 cm). The third experiment was conducted in greenhouse to determine soil cover effects and to evaluate the percentage reduction of dry matter of weeds, where the treatments were mulching with 0, 5, 10, 15 and 20 t ha-1 sugarcane straw. All experiments were conducted in completely randomized design, analyzed separately for each species. No seed was germinated under absence of light. Both species achieved better germination in medium textured soil. It was observed that the emergence of the species was low even without straw. Chloris showed better germination under higher temperatures of 30ºC and 35ºC, although exhibited a drastic decline in the emergence with the increase in soil depth or mulching with sugarcane straw. Greater germination of these weeds occurs in medium textured soils.
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Kaizu, Yutaka, Tetsuo Shimada, Yusuke Takahashi, Sho Igarashi, Hiroyuki Yamada, Kenichi Furuhashi e Kenji Imou. "Development of a Small Electric Robot Boat for Mowing Aquatic Weeds". Transactions of the ASABE 64, n. 3 (2021): 1073–82. http://dx.doi.org/10.13031/trans.14295.
Testo completoAbstract (sommario):
HighlightsA small, automatically guided electric robot boat was developed to control the growth of aquatic plants in lakes.The robot boat was able to mow without becoming entangled with aquatic plants due to the paddle propulsion mechanism.The average speed was 0.41 m s-1, and the lateral deviation from the set path was 9.4 cm.The growth restraint effect was confirmed using aerial images collected by a drone.Abstract. At present, aquatic plants are becoming a problem in various lakes. Aquatic weeds that grow to high densities cause decreases in the oxygen concentration in the water, accumulation of sludge, and adverse effects on water use facilities and fisheries. Although there are large machines for cutting and harvesting aquatic plants, their use is limited due to their high cost, large size, and heavy weight. On the other hand, manual cutting is very labor intensive and inefficient. Therefore, in this research, we developed a labor-saving and low-cost robot boat to mow aquatic plants. This robot boat is automatically controlled by a real-time kinematic global navigational satellite system (RTK-GNSS) and is characterized by its small size, light weight, excellent portability, and low energy consumption. In addition, a paddle mechanism that replaces a conventional propeller was introduced as a propulsion mechanism to prevent entanglement of water plants and enable long-term automatic navigation. Mowing lotus (Nelumbo nucifera) in Lake Izunuma, Miyagi prefecture, Japan, confirmed that mowing could be properly conducted with a lateral deviation of 9.4 cm, average speed of 0.41 m s-1, and average power consumption of 518 W even when lotus was at its densest growth. If the cutting width of the robot boat was 1.2 m and the sidelap width was 0.3 m, the theoretical field work rate would be 0.133 ha h-1. Images captured by a drone confirmed that cutting with the robot boat was effective in suppressing the growth of lotus. It was found that the effect of suppressing growth was maximized by mowing at the time when the stopping leaves appeared in the late growth stage of lotus. Keywords: Autonomous navigation, Lotus, Moving baseline, Robot operation system, RTK-GNSS, Virtual private network.
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Masiunas, John, Elizabeth Wahle, Laurel Barmore e Albert Morgan. "A Foam Mulching System to Control Weeds in Tomatoes and Sweet Basil". HortTechnology 13, n. 2 (gennaio 2003): 324–28. http://dx.doi.org/10.21273/horttech.13.2.0324.
Testo completoAbstract (sommario):
A foam mulch system was developed that can be applied as an aqueous mixture of cotton and cellulose fibers, gums, starches, surfactants and saponins and dries to an one inch thick mat. This mulch may overcome the difficulty in applying and lack of persistence with natural mulches. Foam mulch also has the advantage of being able to be incorporated into the soil without requiring disposal like some plastic mulches. The objective of our study was to determine the effect of foam mulch and its color on weed control within the crop row and on yields of basil (Ocimum basilicum) and tomatoes (Lycopersicon esculentum). The foam mulch maintained its integrity for the entire growing season and provided weed control within the crop row comparable to black plastic mulch. The only weeds that emerged in the crop row were through holes in either the black or foam mulch. Foam mulch color did not affect weed control because regardless of color it did not allow light penetration andserved as a physical barrier impeding weed emergence. Basil shoot biomass was not affected by mulch treatment. Mulch color affected early, ripe fruit, and total yield of tomato. Tomato yields in the blue foam were greater than other treatments. Yields in the black foam mulch were similar to those in black plastic mulch. Further research is needed to characterize the effects of foam mulch on crop microenvironment. Currently foam mulch is being commercialized for use in the home landscape and other highvalue situations.
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Batish, Daizy R., Harminder Pal Singh, Ravinder K. Kohli, Shalinder Kaur, Dinesh B. Saxena e Surender Yadav. "Assessment of Phytotoxicity of Parthenin". Zeitschrift für Naturforschung C 62, n. 5-6 (1 giugno 2007): 367–72. http://dx.doi.org/10.1515/znc-2007-5-609.
Testo completoAbstract (sommario):
Phytotoxicity of parthenin, a sesquiterpene lactone, was evaluated against four weedy species (Amaranthus viridis, Cassia occidentalis, Echinochloa crus-galli, and Phalaris minor) through a series of experiments conducted under laboratory or greenhouse conditions to assess its herbicidal potential. Under laboratory conditions, parthenin (0.5 - 2 mm) severely reduced seedling growth (root and shoot) and dry weight of test weeds. However, the effect was greater on root growth. Parthenin (1 mm) suppressed the mitotic activity in the onion root tip cells that could possibly be responsible for the reduction in seedling growth. Both pre- and post-emergent application of parthenin caused a significant loss of chlorophyll pigments and affected photosynthesis. Parthenin (≥1 mm) caused an excessive electrolyte leakage in the plant tissues which was light-dependent. The root inhibition was associated with swelling and blackening of the root tip, shriveling and damage to the epidermal tissue and non-formation of root hairs. The study concludes that parthenin possesses weed-suppressing potential (both pre- and post-).
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Dias-Filho, Moacyr Bernardino. "Physiological responses of two tropical weeds to shade: II. Leaf gas exchange and nitrogen content". Pesquisa Agropecuária Brasileira 34, n. 6 (giugno 1999): 952–61. http://dx.doi.org/10.1590/s0100-204x1999000600005.
Testo completoAbstract (sommario):
Ipomoea asarifolia (Desr.) Roem. & Schultz (Convolvulaceae) and Stachytarpheta cayennensis (Rich) Vahl. (Verbenaceae), two weeds found in pastures and crop areas in the Brazilian Amazonia, Brazil, were grown in controlled environment cabinets under high (800-1000 µmol m-² s-¹) and low (200-350 µmol m-² s-¹) light regimes during a 40-day period. The objective was to determine the effect of shade on photosynthetic features and leaf nitrogen content of I. asarifolia and S. cayennensis. High-irradiance grown I. asarifolia leaves had significantly higher dark respiration and light saturated rates of photosynthesis than low-irradiance leaves. No significant differences for these traits, between treatments, were observed in S. cayennensis. Low-irradiance leaves of both species displayed higher CO2 assimilation rates under low irradiance. High-irradiance grown leaves of both species had less nitrogen per unit of weight. Low-irradiance S. cayennensis had more nitrogen per unit of leaf area than high-irradiance plants; however, I. asarifolia showed no consistent pattern for this variable through time. For S. cayennensis, leaf nitrogen content and CO2 assimilation were inversely correlated to the amount of biomass allocated to developing reproductive structures. These results are discussed in relation to their ecological and weed management implications.
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Papenfus, Heino B., Manoj G. Kulkarni, Martin Pošta, Jeffrey F. Finnie e Johannes Van Staden. "Smoke-Isolated Trimethylbutenolide Inhibits Seed Germination of Different Weed Species by Reducing Amylase Activity". Weed Science 63, n. 1 (marzo 2015): 312–20. http://dx.doi.org/10.1614/ws-d-14-00068.1.
Testo completoAbstract (sommario):
Weeds pose a great problem to farmers worldwide, and controlling weeds demands a high input cost for herbicides and labor. Because of current environmental regulations, a limited number of herbicides are commercially available (with limited modes of action) to control weeds. Smoke water and the biologically active compounds isolated from smoke affect seed germination in a significant way. Smoke water (SW) and karrikinolide (KAR1, the germination stimulant isolated from smoke) have been tested extensively for their ability to promote seed germination in a vast array of plant species. In addition to KAR1, a germination inhibitor, trimethylbutenolide (TMB), was also isolated from plant-derived smoke. The effects of SW, KAR1, and TMB were tested on five major weed species of South Africa: fleabane, hairy wild lettuce, bugweed, spilanthes, and fameflower. Seeds of these weed species were subjected to 16/8 h light/dark conditions or to constant dark conditions at constant temperatures of 20, 25, 30 C and alternating 30/20 C. SW and KAR1significantly increased germination, whereas TMB significantly inhibited germination of these weed species. Furthermore, TMB treatment reduced the amylase activity of the tested weed seeds compared with the water control. These results indicate the possibility of manipulating germination of certain weed seeds by SW, KAR1, and TMB. Thus, smoke and smoke-isolated compounds could potentially be used in new weed management strategies.
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Karki, Tika Bahadur, Shrawan K. Sah, Resam B. Thapa, Andrew J. McDonald, Adam S. Davis e Yajna G. Khadka. "Weeds and Their Effect on the Performance of Maize and Finger Millet in Mid-Hills of Nepal". International Journal of Applied Sciences and Biotechnology 2, n. 3 (25 settembre 2014): 275–78. http://dx.doi.org/10.3126/ijasbt.v2i3.10790.
Testo completoAbstract (sommario):
Relay cropping of maize with fingermillet (maize/fingermillet) is the predominant cropping system for sustaining food security situation in the hilly regions of Nepal. In this region weed pressure severely reduces crop yields. Basic information on weed species composition, biomass production and their effect on crop yields and economics are lacking for this region. This information will be necessary to develop effective weed management strategies for the future. In light of this an empirical study was carried out in two representatives mid hill districts of Parbat and Baglung during summer season of 2010/2011 in Nepal. A total of 10 major weed species with densities of 172 in Parbat and 311 per 0.25m2 area in Baglung were observed. The highest percentage of both relative and absolute densities were recorded for Ageratum conyzoides in Parbat and Polygonum chinensis in Baglung. Weed infestation under farmers practice of crop management reduced the grain yield of maize by 1.985 Mt ha-1 (117%) in Baglung and 1.760 Mt ha-1 (108%) in Parbat. Similarly, in finger millet it was 0.489 Mt ha-1 (63%) in Baglung and 0.403 Mt ha-1 in Parbat. Similarly, the combined yield of both the crops was also significantly reduced by 79.3% and 61.7% in Baglung and Parbat respectively. Hence, weeds are directly affecting the crop performance in the region. Therefore, there is an urgent need to develop an alternative crop production system in the hills. DOI: http://dx.doi.org/10.3126/ijasbt.v2i3.10790Int J Appl Sci Biotechnol, Vol. 2(3): 275-278
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Matyuk, Nikolay, Valery Polin e Anton Ananyev. "Effectiveness of herbicides in the destruction of weeds and carrion of spring rapeseed in the link of the crop rotation of spring rapeseed - spring wheat in the conditions of the Tula region". АгроЭкоИнфо 3, n. 51 (27 giugno 2022): 19. http://dx.doi.org/10.51419/202123319.
Testo completoAbstract (sommario):
Studies conducted in the production conditions of the Tula region have shown that the cultivation of spring wheat after spring rapeseed using technologies without the use of dump plowing at the early stages of crop development leads to a problem with the fall of spring rapeseed. As a weed, it rises simultaneously or earlier than spring wheat, develops faster, competing with the crop for nutrients, soil moisture and light. The task of the research was to determine the optimal timing of the use of various herbicides and their tank mixtures in order to destroy weeds and, above all, rapeseed carrion. It has been found that their use is more effective in the middle of the tillering phase of spring wheat, as this avoids the negative effects of drugs on the culture, effectively destroying weeds and rapeseed carrion. The use of herbicides in the middle of the tillering phase of the crop led to an increase in the yield of spring wheat by 0.33 - 0.48 t/ha compared with the control variant. Keywords: SPRING WHEAT, RAPESEED CARRION, CROP ROTATION, WEEDS, HERBICIDES, YIELD