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Monks, C. Dale, David W. Monks, Tom Basden, Arthur Selders, Suzanne Poland e Edward Rayburn. "Soil Temperature, Soil Moisture, Weed Control, and Tomato (Lycopersicon esculentum) Response to Mulching". Weed Technology 11, n. 3 (settembre 1997): 561–66. http://dx.doi.org/10.1017/s0890037x00045425.
Testo completoAbstract (sommario):
Shredded newspaper (2.5, 7.6, 12.7, and 17.8 cm depth), chopped newspaper (2.5 and 7.6 cm), wheat straw (15.2 cm), black plastic, and plastic landscape fabric were evaluated during 1993 and 1994 in West Virginia for their effect on soil temperature, soil moisture, weed control, and yield in tomato. Shredded newspaper and wheat straw applied at 0, 2, 4, or 6 weeks after transplanting (WAT) and napropamide (2.1 kg ai/ha) plus metribuzin (0.28 kg ai/ha) applied at transplanting were evaluated during 1992 and 1993 in North Carolina for effect on weed control and tomato yield. Results from West Virginia indicated that shredded (7.6 cm) and chopped (7.6 cm) newspaper conserved moisture similar to higher application rates of the shredded material. Higher newspaper mulching rates reduced soil temperature compared to black plastic and bare ground. Chopped newspaper controlled weeds more consistently than other treatments. At least 7.6 cm of chopped newspaper mulch was required to control weeds at least 90%. Wheat straw was not as effective in controlling weeds as 7.6 cm or greater of newspaper mulch. Chopped newspaper provided higher tomato yields than shredded newspaper applied at the same rates. Mulches applied at 0, 2, or 4 WAT resulted in weed control similar to the chemical treatment. In North Carolina, mulches applied 2 or 4 WAT resulted in tomato yields similar to the chemical treatment. Shredded and chopped newspaper have potential as a mulching material but may vary in effect in different environments and vegetable crops.
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Aziz, Fahrurrozi, e Katrine A. Stewart. "EFFECT OF SPECTRAL QUALITIES OF PLASTIC MULCH ON WEED DEVELOPMENT AND GROWTH". HortScience 29, n. 4 (aprile 1994): 251c—251. http://dx.doi.org/10.21273/hortsci.29.4.251c.
Testo completoAbstract (sommario):
The types of plastic mulch used in horticultural production often fulfill only a few of the grower's needs. Black plastic mulch controls weeds, but can burn young plants. Clear mulch, while warming the soil and enhancing early crop growth, allows prolific weed growth and development. Accordingly, an experiment using a randomized complete-block design with-four replications was set up to compare the effects of black, microperforated black, silver, and wavelength-selective (IRT-76) green mulches, and bare soil on weed growth and development, and on soil temperature and moisture. Each mulch was evaluated for its optical properties. All mulches significantly reduced final stands of seeded weeds compared with bare soil. IRT-76 green had the warmest mean soil temperatures, followed by silver, black, and microperforated black mulches, and bare soil. Soil moisture content was generally higher under plastic mulches than bare soil.
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Kumar, Vipin, Annu Kumari, Andrew J. Price, Ram Swaroop Bana, Vijay Singh e Shanti Devi Bamboriya. "Impact of Futuristic Climate Variables on Weed Biology and Herbicidal Efficacy: A Review". Agronomy 13, n. 2 (15 febbraio 2023): 559. http://dx.doi.org/10.3390/agronomy13020559.
Testo completoAbstract (sommario):
Our changing climate will likely have serious implications on agriculture production through its effects on food and feed crop yield and quality, forage and livestock production, and pest dynamics, including troublesome weed control. With regards to weeds, climatic variables control many plant physiology functions that impact flowering, fruiting, and seed dormancy; therefore, an altered climate can result in a weed species composition shift within agro-ecosystems. Weed species will likely adapt to a changing climate due to their high phenotypic plasticity and vast genetic diversity. Higher temperatures and CO2 concentrations, and altered moisture conditions, not only affect the growth of weeds, but also impact the effectiveness of herbicides in controlling weeds. Therefore, weed biology, growth characteristics, and their management are predicted to be affected greatly by changing climatic conditions. This manuscript attempted to compile the available information on general principles of weed response to changing climatic conditions, including elevated CO2 and temperature under diverse rainfall patterns and drought. Likewise, we have also attempted to highlight the effect of soil moisture dynamics on the efficacy of various herbicides under diverse agro-ecosystems.
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Wright, Shawn R., Harold D. Coble, C. David Raper e Thomas W. Rufty. "Comparative responses of soybean (Glycine max), sicklepod (Senna obtusifolia), and Palmer amaranth (Amaranthus palmeri) to root zone and aerial temperatures". Weed Science 47, n. 2 (aprile 1999): 167–74. http://dx.doi.org/10.1017/s004317450009158x.
Testo completoAbstract (sommario):
Experiments were conducted to compare germination efficiencies and vegetative growth of soybean and the competing weed species, sicklepod and Palmer amaranth, over a range of temperatures in the root zone and aerial environments. From genetic origins we hypothesized that the weeds would have a higher temperature optimum, which would help explain competitive interactions seen in the southeastern U.S. Germination experiments indicated that germination efficiency of the weeds was much more sensitive to low temperature than soybean, being markedly inhibited below 18 C. Similarly, experiments in an automated, temperature-controlled hydroponic system revealed that the weed species were less tolerant of low root zone temperature but more tolerant of high root zone temperature than soybean. At 16 C, dry weight of soybean was 74% of the control dry weight at 24 C, whereas dry weights of sicklepod and Palmer amaranth were 5 and 20% of the control, respectively. At 32 C, soybean root dry weight was only 80% of the 24 C treatment, whereas root dry weight of the weed species was not significantly different. When plants were grown at a low aerial temperature, growth of all plants was strongly inhibited] but the negative effects were somewhat more severe in the weed species than with soybean. An increase in aerial temperature from 26/22 C to 34/30 C (day/night) had a positive influence on dry matter accumulation of the weed species, stimulating sicklepod 150 to 200% and Palmer amaranth 150 to 1,600% compared to their respective controls, whereas soybean remained at about 80 to 90% of the control. All species grew taller with increasing temperature. Leaf area of the weeds increased but leaf area of soybean did not increase. Consistent with our original hypothesis, the results clearly show that the weeds, which originate from warm geographical regions, respond more negatively than soybean to low temperatures in the growth environment but more positively to high temperatures. The temperature characteristics help to explain why the intensity of weed pressure increases as the soybean growing season progresses, even after canopy closure.
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Park, Hyun-Hwa, Do-Jin Lee e Yong-In Kuk. "Effects of Various Environmental Conditions on the Growth of Amaranthus patulus Bertol. and Changes of Herbicide Efficacy Caused by Increasing Temperatures". Agronomy 11, n. 9 (3 settembre 2021): 1773. http://dx.doi.org/10.3390/agronomy11091773.
Testo completoAbstract (sommario):
Understanding the effects of climate change on weed growth and herbicide activity is important for optimizing herbicide applications for effective weed control in the future. Therefore, this study examined how climate change affects the growth of Amaranthus patulus and the efficacy of soil and foliar herbicides at different temperatures. Although the control values for A. patulus differed between herbicides and temperature, the control values increased with increasing time after the herbicide treatments. Under growth conditions in which the temperature remained constant, the efficacy of soil-applied herbicides, ethalfluralin, metolachlor, linuron, and alachlor, on A. patulus was highest when the weeds were grown at high temperature. In particular, 100% control values of A. patulus were achieved in response to metolachlor treatments at the total recommended dosage in growth chambers at 35 °C. The efficacy of foliar herbicides, glufosinate-ammonium, bentazone, and mecoprop, on A. patulus was also highest when the plant was grown at high temperature, except for glyphosate isopropylamine, which had similar efficacy rates regardless of the temperature. A. patulus was 100% controlled in response to glufosinate-ammonium, bentazone, and mecoprop at the recommended dosages in growth chambers at 30 and 35 °C. Under growth conditions in which the temperature changed from day to night, the efficacy of soil-applied herbicides, alachlor and linuron, on A. patulus was highest when the weeds were grown at high temperature. On the other hand, the efficacy of the soil-applied herbicides metolachlor and linuron on A. patulus was similar regardless of the temperature. The efficacy of foliar herbicides, glyphosate isopropylamine, glufosinate-ammonium, bentazone, and mecoprop, on A. patulus was highest when the weeds were grown at high temperature. Although herbicide efficacy varied depending on whether the weeds were grown at constant or alternating temperatures, herbicide efficacy was generally highest when the temperature was high.
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Kirigiah, Richard, Masinde Peter e Mworia G. Erick. "Effect of Plastic Mulch Color and Transplanting Stage on Baby Corn Plant Performance". European Journal of Agriculture and Food Sciences 4, n. 5 (20 ottobre 2022): 103–11. http://dx.doi.org/10.24018/ejfood.2022.4.5.567.
Testo completoAbstract (sommario):
Different colored plastic mulches have been developed and used in various crop production methods. The main goals of using colored plastic mulches are to modify the radiation budget and reduce soil water loss. In addition, it aids in controlling weed and insect infestation as well as soil temperature, water use effectiveness, plant development, yield, and quality. The growth and development of baby corn depend on several geographical and climatic conditions in its surrounding (air and soil). This study determined the effect of different colored plastic mulches on soil temperature and the performance of two baby corn varieties (Pan 14 and Thai Gold). Black plastic mulches showed significantly higher soil temperatures, followed by transparent films, yellow films, and non-mulched, respectively. However, there were no significant changes in soil temperatures over the 17 weeks for specific plastic mulches. Pan 14 produced a higher yield and displayed improved vegetative growth compared to Thai Gold under similar conditions. Transparent plastic mulches showed the best yield and vegetative growth for both varieties but could not effectively control weeds. Black plastic mulches produced significantly higher yield and vegetative performance than non-mulched but were lower than the transparent film performance. Additionally, black plastic mulches showed better performance on weed minimization. The combined results indicated that the effect of colored plastic mulches is highly significant on soil temperature, moisture, and water-holding capacity. While black plastics increase soil temperature, transparent and yellow decrease it.
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Tremmel, D. C., e D. T. Patterson. "Effects of elevated CO2 and temperature on development in soybean and five weeds". Canadian Journal of Plant Science 74, n. 1 (1 gennaio 1994): 43–50. http://dx.doi.org/10.4141/cjps94-009.
Testo completoAbstract (sommario):
Developmental rates of soybean [Glycine max (L.) Merr. 'Braxton'], johnsongrass [Sorghum halepense (L.) Pers.], quackgrass [Elytrigia repens (L.) Nevski], redroot pigweed (Amaranthus retroflexus L.), sicklepod (Cassia obtusifolia L.), and velvetleaf (Abutilon theophrasti Medic.) were compared among plants grown in all combinations of two temperature levels (avg. day/night of 26/19 °C and 30/23 °C) and two CO2 levels (350 and 700 ppm). Neither temperature nor CO2 affected johnsongrass tillering rate, but plants began tillering earlier at higher temperatures. Adverse effects of higher temperatures on quackgrass development were alleviated by elevated CO2 conditions. Plastochron rate was higher at higher temperatures in all dicot species (soybean, redroot pigweed, sicklepod, and velvetleaf), and was higher at elevated CO2 in all dicots except velvetleaf. Calculating plastochron rates on a degree day basis removed differences between temperature treatments, but did not affect responses to CO2. Responses of dicot branch and branch leaf production to treatments varied among species. Branch production per day increased with higher temperatures in redroot pigweed, decreased with higher temperatures in sicklepod, and was unaffected by temperature in soybean. The relationship between main axis and branch developmental rates was altered by temperature in soybean, and by both temperature and CO2 in sicklepod, but was unaffected by either treatment in redroot pigweed. These results indicate that developmental responses to temperature and CO2 depend on both the species and the aspect of development being considered. Key words: Plastochron index, CO2 by temperature interaction, johnsongrass, quackgrass, redroot pigweed, sicklepod, velvetleaf
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Martinez-Ghersa, Maria A., Emilio H. Satorre e Claudio M. Ghersa. "Effect of soil water content and temperature on dormancy breaking and germination of three weeds". Weed Science 45, n. 6 (dicembre 1997): 791–97. http://dx.doi.org/10.1017/s0043174500088986.
Testo completoAbstract (sommario):
In laboratory experiments, we studied barnyardgrass, common lambsquarters, and redroot pigweed seed dormancy release by alternating temperatures under different soil water regimes, to determine whether that response serves as a mechanism for assuring seedling establishment. Alternating temperatures were important in breaking seed dormancy in the three weeds, but the species' response to alternating temperatures differed with soil water content. For redroot pigweed and newly dispersed seeds of barnyardgrass, dormancy breaking by alternating temperatures occurred only when soil water content was high enough for germination. Moreover, adverse incubation conditions (constant temperature and low water content) induced secondary dormancy in these seeds. Seventy percent of seeds incubated in open boxes emerged before the soil reached wilting point, when seeds were incubated at temperatures high enough for a high germination rate. A dormancy breaking mechanism that triggers a high rate of germination may be important in assuring success of seedling establishment where rainfall patterns result in wetting and drying cycles of the soil, especially in soil types that lose water rapidly from the surface layers.
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Swanton, Clarence J., Jian Zhong Huang, William Deen, Matthijs Tollenaar, Anil Shrestha e Hamid Rahimian. "Effects of temperature and photoperiod onSetaria viridis". Weed Science 47, n. 4 (agosto 1999): 446–53. http://dx.doi.org/10.1017/s0043174500092067.
Testo completoAbstract (sommario):
Understanding the environmental variables influencing the phenological development of weeds is essential for simulation model development. Temperature and photoperiod are important variables governing the phenological development of weeds. Growth cabinet studies were conducted to characterize the phenological development ofSetaria viridisin response to variations in temperature and photoperiod and to determine the duration of the juvenile phase and the effect of temperature and photoperiod on reproductive development.Setaria viridiswas adapted to a temperature range from 6.5 to 47 C. Phenological development ofS. viridiswas described accurately in terms of thermal days (cumulative day degrees above a base temperature) and biological days (Bd: chronological days at the optimum temperature and photoperiod). Four developmental phases ofS. viridiswere described: (1) a juvenile (photoperiod insensitive) phase of 2.6 Bd; (2) a photoperiod-sensitive inductive phase of 2.2 Bd; (3) a photoperiod-sensitive postinductive phase of 6.0 Bd; and (4) a photoperiod-insensitive inductive phase of 10.9 Bd. Photoperiod sensitivity ofS. viridisdid not differ with stage of development when expressed as a rate. Interpretation of constant sensitivity to photoperiod will simplify simulation of weed phenology in mechanistic models.
10
WEAVER, S. E., C. S. TAN e P. BRAIN. "EFFECT OF TEMPERATURE AND SOIL MOISTURE ON TIME OF EMERGENCE OF TOMATOES AND FOUR WEED SPECIES". Canadian Journal of Plant Science 68, n. 3 (1 luglio 1988): 877–86. http://dx.doi.org/10.4141/cjps88-105.
Testo completoAbstract (sommario):
The relative times to emergence of seedlings of tomato (Lycopersicon esculentum L.) and four weed species were compared at five alternating temperatures and five levels of available soil moisture in a growth chamber. Weed seeds were sown either on the soil surface or 1.5 cm below it. A cumulative distribution function was used to describe the time required for emergence under a given set of conditions. Time to 50% emergence, base temperatures and accumulated degree days required for 50% emergence were calculated for each species. In general, total emergence decreased as soil moisture decreased, but the species differed in the optimum temperature for emergence. Time to 50% emergence decreased with increasing temperature and increased slightly with decreasing soil moisture. Base temperatures and thermal times required for 50% emergence varied among species, but were relatively insensitive to soil moisture above a critical level. Differences in relative times to emergence of crop and weeds in response to temperature can be used to suggest optimal crop sowing dates and to estimate potential crop yield losses.Key words: Germination, Solanum ptycanthum, Amaranthus powellii, Setaria viridis, Chenopodium album, Lycopersicon esculentum
11
Gandía, María Luisa, Carlos Casanova, Francisco Javier Sánchez, José Luís Tenorio e María Inés Santín-Montanyá. "Arable Weed Patterns According to Temperature and Latitude Gradient in Central and Southern Spain". Atmosphere 11, n. 8 (13 agosto 2020): 853. http://dx.doi.org/10.3390/atmos11080853.
Testo completoAbstract (sommario):
(1) Background: In agro-ecosystems, the success of the crops has a strong connection to biodiversity in the landscape. In the face of climate change, it is important to understand the response to environmental variation of weed species by means of their distribution. In the last century, biodiversity has been impacted due to a variety of stresses related to climate change. Although the composition of vegetation tends to change at a slower rate than climate change, we hypothesize species present in weed communities are distributed in diverse patterns as a response to the climate. Therefore, the general aim of this paper is to investigate the effect of temperature, using latitude as an indicator, on the composition and distribution of weed communities in agro-ecosystems. (2) Methods: Weeds were monitored in georeferenced cereal fields which spanned south and central Spanish regions. The graphic representation according to latitude allowed us to identify groups of weeds and associate them to a temperature range. We classified weeds as generalist, regional, or local according to the range of distribution. (3) Results: The monitoring of species led to the classification of weeds as generalist, regional or local species according to latitude and associated temperature ranges. Three weed species that were present in all latitude/temperature regions, were classified as generalist (Linaria micrantha (Cav) Hoffmanns & Link, Sonchus oleraceous L., and Sysimbrium irium L.). The species were classified as regional or local when their presence was limited to restricted latitude/temperature ranges. One weed, Stellaria media (L.) Vill., was considered a local species and its distribution dynamics can be considered an indicator of temperature. (4) Conclusions: The novel methodology used in this study to assign weed distribution as an indicator of climatic conditions could be applied to evaluate climate gradients around the world.
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Tremmel, David C., e David T. Patterson. "Responses of soybean and five weeds to CO2 enrichment under two temperature regimes". Canadian Journal of Plant Science 73, n. 4 (1 ottobre 1993): 1249–60. http://dx.doi.org/10.4141/cjps93-164.
Testo completoAbstract (sommario):
Rising atmospheric CO2 levels could affect plant growth both directly, through effects on physiology, and indirectly, through the effects of possible CO2-induced temperature increases. In this study we examined the interacting effects of CO2 enrichment and temperature on the growth and allocation of soybean and five weeds. Individual plants of soybean [Glycine max (L.) Merr. ’Braxton’], johnsongrass [Sorghum halepense (L.) Pers.], quackgrass [Elytrigia repens (L.) Nevski], redroot pigweed (Amaranthus retroflexus L.), sicklepod (Cassia obtusifolia L.), and velvetleaf (Abutilon theophrasti Medic.) were grown in growth chambers in all combinations of two temperatures (avg. day/night of 26/19 °C and 30/23 °C) and two CO2 concentrations (350 and 700 ppm) for 35 d. Leaf area and plant biomass were greater at higher temperatures, regardless of CO2 level, in all species except quackgrass. Quackgrass (C3) produced its greatest leaf area and biomass at elevated CO2, whereas johnsongrass (C4) showed little response. Redroot pigweed (C4) and the C3 dicotyledenous species (soybean, sicklepod, velvetleaf) produced their greatest biomass at high CO2, though effects on leaf area were less consistent or absent. In general, when significant CO2 by temperature interactions were found, CO2 responses were smallest at higher temperatures. These differential responses to elevated CO2 concentrations may cause changes in the relative importance of competitive pressure from these weeds. Key words: CO2 by temperature interaction, soybean, johnsongrass, quackgrass, redroot pigweed, sicklepod, velvetleaf
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Martinez, Nayeli, e Erick De la Barrera. "Germination Ecophysiology for Three Peri-urban Ephemeral Weeds from Morelia, Michoacan, Mexico". La Granja 31, n. 1 (28 febbraio 2020): 47–55. http://dx.doi.org/10.17163/lgr.n31.2020.03.
Testo completoAbstract (sommario):
The environmental requirements leading to germination were determined by three common species found during the June-October 2009 rainy season in a peri-urban site from Morelia, Michoacan, Mexico, where the construction of a campus of the Universidad Nacional Autonoma de Mexico (UNAM) was underway. In particular, we evaluated responses in the laboratory to low-temperature stratification, day/night air temperature, and water potential for the native Onagraceae Lopezia racemosa and Ludwigia octovalvis, and the exotic Polygonaceae Rumex crispus. Low-temperature stratification had no effect on germination by L. racemosa, for which maximum germination averaging 88% was optimal at 25/15 and 30/20 ºC. Germination at 21 d was halved at –0.5 MPa and completely inhibited at –1.0 MPa. The seeds of L. octovalvis were also insensitive to low temperature stratification and their germination never exceeded 70%, with the two highest temperatures of 30/20 and 35/25 ºC being the optimum. For this species germination was maximal at 0.0 MPa, decreasing significantly under every treatment with a minimum germination of 21% for seeds incubated at –0.1 MPa. Germination for the exotic R. crispus was delayed by low-temperature stratification, although all its seeds germinated regardless of the temperature or water potential treatment. While the environmental requirements for germination of ephemeral species often match the typical climate of their growing season, the differential responses found for the species considered in the present study provide some insight into the mechanisms leading to changes in species composition for communities from disturbed environments, including the displacement of native species and the proliferation of exotic, potentially invasive plants.
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Karkanis, A., G. Ntatsi, A. Alemardan, S. Petropoulos e D. Bilalis. "Interference of weeds in vegetable crop cultivation, in the changing climate of Southern Europe with emphasis on drought and elevated temperatures: a review". Journal of Agricultural Science 156, n. 10 (dicembre 2018): 1175–85. http://dx.doi.org/10.1017/s0021859619000108.
Testo completoAbstract (sommario):
AbstractIt is challenging to predict the changes in weed flora that may occur because of changes in global climate. Limited data are available on the effect of climate change and drought conditions on weed flora and their competitiveness in Southern Europe. Future predictions by scientists indicate reduced and untimely rainfall, along with increased temperatures in this region. Weeds possess a variety of developmental and physiological mechanisms, including senescing, increased leaf cuticular wax deposition, well-developed palisade parenchyma in the leaves, high root/shoot ratio, stomatal closure, peroxidase accumulation and symbiosis with endophytes that enable them to adapt to drought and high temperatures. Because of high adaptability of weeds to adverse environmental conditions, it can be assumed that under future warmer and drier environmental conditions, their growth will be favoured, while the competitiveness of vegetable crops against weeds will be decreased. It is important to highlight that the predicted decrease in overall rainfall levels throughout the year may lead to increased problems of herbicide residues (carryover effects) to following crops. The current paper provides an up-to-date overview of the adaptation mechanisms of weed species commonly found in Southern Europe, in order to expand the available knowledge regarding their response to drought and elevated temperatures. Emphasis is placed on revealing the effects of drought and increased temperatures on vegetable–weed competition and, most importantly, its effect on vegetable crop yield.
15
RODENBURG, J., H. MEINKE e D. E. JOHNSON. "Challenges for weed management in African rice systems in a changing climate". Journal of Agricultural Science 149, n. 4 (25 febbraio 2011): 427–35. http://dx.doi.org/10.1017/s0021859611000207.
Testo completoAbstract (sommario):
SUMMARYGlobal changes including increases in temperature, atmospheric greenhouse gases, soil degradation and competition for land and water resources, will have multiple impacts on rice production systems in Africa. These changes will affect weed communities, and management approaches must be adapted to take this into account. Higher temperatures and limited water availability will generally advantage C4over C3plants (e.g. rice). Conversely, elevated carbon dioxide (CO2) levels will improve the competitiveness of rice relative to C4weeds, which comprise many of the problem weeds of rice. Increased atmospheric CO2levels may also improve tolerance of rice against parasitic weeds, while prevalence of parasitic species may be amplified by soil degradation and more frequent droughts or floods. Elevated CO2levels tend to promote growth below-ground relative to above-ground, particularly in perennial (C3) species. This may render mechanical control of weeds within a cropping season less effective or even counterproductive. Increased CO2levels, rainfall and temperature may also reduce the effectiveness of chemical control, while the implementation of adaptation technologies, such as water-saving irrigation regimes, will have negative consequences for rice–weed competition. Rain-fed production systems are prevalent throughout Africa and these are likely to be most vulnerable to direct effects of climate change (e.g. higher temperatures and changes in rainfall patterns). Effective weed management strategies in these environments could encompass off-season tillage, the use of well-adapted cultivars (i.e. those with drought and heat tolerance, high weed competitiveness and parasitic weed resistance or tolerance) and rotations, intercropping or short, off-season fallows with weed-suppressive legumes including those that suppress parasitic weeds. In irrigated, non-flooded rice systems, weeds are expected to become more serious. Specifically, perennial rhizomatous C3weeds and species adapted to hydromorphic conditions are expected to increase in prevalence. By implementing an integrated weed management strategy primarily targeted at weed prevention, dependency on flood water, herbicides and mechanical control can be lessened. Off-season deep tillage, stale seed bed techniques, use of clean seeds and irrigation water, competitive cultivars, timely transplanting at optimum spacing and judicious fertilizer timings are suitable candidate components for such a strategy. Integrated, novel approaches must be developed to assist farmers in coping with the challenges of weed control in the future.
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Alberto, AMP, LH Ziska, CR Cervancia e PA Manalo. "The Influence of Increasing Carbon Dioxide and Temperature on Competitive Interactions Between a C3 Crop, Rice (Oryza sativa) and a C4 Weed (Echinochloa glabrescens)". Functional Plant Biology 23, n. 6 (1996): 795. http://dx.doi.org/10.1071/pp9960795.
Testo completoAbstract (sommario):
Many of the most troublesome weeds in agricultural systems are C4 plants. As atmospheric CO2 increases it is conceivable that competitive ability of these weeds could be reduced relative to C3 crops such as rice. At the International Rice Research Institute (IRRI) in the Philippines, rice (IR72) and one of its associated C4 weeds, Echinochloa glabrescens, were grown from seeding to maturity using replacement series mixtures (100:0, 75:25, 50:50, 25:75, and 0:100, % rice:%weed) at two different CO2 concentrations (393 and 594 μL L-1) in naturally sunlit glasshouses. Since increasing CO2 may also result in elevated growth temperatures, the response of rice to each CO2 concentration was also examined at daylnight temperatures of 27/21 and 37/29�C. At 27/21�C, increasing the CO2 concentration resulted in a significant increase in above ground biomass (+47%) and seed yield (+55%) of rice when averaged over all mixtures. For E. glabrescens, the C4 species, no significant effect of CO2 concentration on biomass or yield was observed. When grown in mixture, the proportion of rice biomass increased significantly relative to that of the C4 weed at all mixtures at elevated CO2. Evaluation of changes in competitiveness (by calculation of plant relative yield (PRY) and replacement series diagrams) of the two species demonstrated that, at elevated CO2, the competitiveness of rice was increased relative to that of E. glabrescens. However, at the higher growth temperature (37/29�C), growth and reproductive stimulation of rice by elevated CO2 was reduced compared to the lower growth temperature. This resulted in a reduction in the proportion of rice:weed biomass present in all mixtures relative to 27/21�C and a greater reduction in PRY in rice relative to E. glabrescens. Data from this experiment suggest that competitiveness could be enhanced in a C3 crop (rice) relative to a C4 weed (E. glabrescens) with elevated CO2 alone, but that simultaneous increases in CO2 and temperature could still favour a C4 species.
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MURAKAMI, Toshio, Yasuo DOI e Hirohiko MORITA. "Effect of temperature on leaf-emergence of paddy weeds in the cold region and regional differences." Journal of Weed Science and Technology 32, n. 2 (1987): 112–22. http://dx.doi.org/10.3719/weed.32.112.
Testo completo
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Brainard, Daniel C., William S. Curran, Robin R. Bellinder, Mathieu Ngouajio, Mark J. VanGessel, Milton J. Haar, W. Thomas Lanini e John B. Masiunas. "Temperature and Relative Humidity Affect Weed Response to Vinegar and Clove Oil". Weed Technology 27, n. 1 (marzo 2013): 156–64. http://dx.doi.org/10.1614/wt-d-12-00073.1.
Testo completoAbstract (sommario):
Nonsynthetic herbicides offer a potentially useful addition to the suite of weed management tools available to organic growers, but limited information is available to guide the optimal use of these products. The objectives of this research were to (1) evaluate the efficacy of clove oil– and vinegar-based herbicides on weeds across multiple states, and (2) assess the potential role of temperature, relative humidity (RH), and cloud cover in explaining inter-state variations in results. From 2006 to 2008, a total of 20 field trials were conducted in seven states using an identical protocol. Seeds of brown mustard were sown and herbicides applied to both mustard and emerged weeds when mustard reached the three- to four-leaf stage. Treatments included clove oil at 2.5, 5, 7.5, and 10% v/v concentrations at 54 L ha−1, and vinegar at 5, 10, 15, and 20% v/v concentrations at 107 L ha−1. Results varied widely across trials. In general, concentrations of at least 7.5% for clove oil and 15% for vinegar were needed for adequate control of mustard. Both products were more effective at suppressing mustard thanAmaranthusspp. or common lambsquarters. Poor control was observed for annual grasses. No significant effects of cloud cover on the efficacy of either product were detected. In contrast, RH was positively correlated with control of brown mustard by both clove oil and vinegar with improved control at higher RH. Temperature had no detectable effect on the efficacy of clove oil, but higher temperatures improved control of brown mustard by vinegar.
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Petrikovszki, Renáta, Mihály Zalai, Franciska Tóthné Bogdányi e Ferenc Tóth. "The Effect of Organic Mulching and Irrigation on the Weed Species Composition and the Soil Weed Seed Bank of Tomato". Plants 9, n. 1 (3 gennaio 2020): 66. http://dx.doi.org/10.3390/plants9010066.
Testo completoAbstract (sommario):
Mulching is a management technique to control weeds in organic and integrated tomato production. Our experiment was designed to investigate the impact of organic mulch combined with irrigation on the weed species composition and weed seed bank of open-field tomato. For three consecutive years (2016–2018), treatment of microplots included mulch only, irrigation only, mulch and irrigation combined, and the untreated control. Marginal microplots (bordered by the surrounding mown grassland) were distinguished from inner microplots to check margin effect. We collected soil samples from different depths and let the weed seeds germinate in a greenhouse. Germinated weed seedlings were counted and identified. The number of weeds, and time needed for weeding was reduced by mulching, temperature, sampling date, and the succession of the study years. Irrigation, on the other hand, had no effect on weeding time. Margin effect and year had the highest influence on weed species composition. Regarding seed bank, year and mulching had the highest influence. The importance of other variables remained low, with mulching being the strongest explained variable. Regardless of treatments, weed composition of the study area was transformed during the three-year study.
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Lalbiakdika, H. Lalruatsanga e F. Lalnunmawia. "Allelopathic effect of common weeds on germination and seedling growth of rice in wetland paddy fields of Mizoram, India". Plant, Soil and Environment 68, No. 8 (29 agosto 2022): 393–400. http://dx.doi.org/10.17221/167/2022-pse.
Testo completoAbstract (sommario):
Weed invasion of crops contested for environmental resources alongside releasing a certain chemical into the soil and thereby lowering yield potential. The possible allelopathic influence of aqueous extract from leaves and shoots of Alternanthera philoxeroides (Mart.) Griseb., Ludwigia octovalvis (Jacq.) P.H. Raven and Persicaria hydropiper (L.) Delarbe on germination and seedling growth of rice (Oryza sativa L.) was investigated in this study. To prepare the extract, powdered air-dried leaves and shoots of certain weeds were soaked in distilled water (1 : 10) for 24 h at room temperature, and a different dilution was made from the stock. Aqueous extracts from various plant parts were found to suppress seed germination and the development of rice seedlings. As the extract concentration increases, the intensity of inhibition on germination, shoot length, root length and dry matter reduction increases. The average percent inhibition (API) of leaf extract treatments, namely 8% and 10% A. philoxeroides, 8% and 10% L. octovalvis, and 10% P. hydropiper, was found to be greater than 45%. Shoot extracts containing 2% A. philoxeroides, 2% and 4% L. octovalvis, and 2% P. hydropiper have less than 15% average percent inhibition. According to the findings, different weeds contain allelochemicals of variable types and quantities, and different portions of the same weed have distinct effects on germination and rice seedling development.
21
Nakatani, Keiko, e Tokuichi Kusanagi. "Effect of photoperiod and temperature on growth characteristics, especially heading or flower bud appearance of upland weeds." Journal of Weed Science and Technology 36, n. 1 (1991): 74–81. http://dx.doi.org/10.3719/weed.36.74.
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Mas-Ud, Mustapha, Fuseini Dokurugu e James Seutra Kaba. "Effectiveness of cowpea (Vigna unguiculata L.) living mulch on weed suppression and yield of maize (Zea mays L.)". Open Agriculture 6, n. 1 (1 gennaio 2021): 489–97. http://dx.doi.org/10.1515/opag-2021-0031.
Testo completoAbstract (sommario):
Abstract Weed control plays a vital role in achieving higher maize yield. We tested the hypothesis that interseeding cowpea as living mulch with maize will reduce biomass and diversity of weeds, and improve soil physical properties and maize yield. In 2017/2018 cropping seasons, a 2 × 4 factorial experiment was laid in a randomized complete block design with three replications at the Savelugu Municipality of Northern Ghana. The factorial treatment consisted of three cowpea varieties interseeded with two maize genotypes and a control (maize with no living mulch). Our result showed that, in both seasons, weed biomass and diversity, soil temperature, and grain yield were significantly (p < 0.05) higher in control plots than in cowpea living mulch plots at all growth stages of both maize varieties. However, maize growth was not affected by weeds at tasseling. We established that cowpea varieties as living mulch in maize cropping have similar effect on soil moisture and temperature but have varying degrees of suppressing weeds and improving maize yield. The cowpea living mulch had weed biomass of 0.5 t ha−1 compared to 2.6 t ha−1 in the control. In addition, living mulch plots had maize grain of 2 t ha−1 and stover yield of 3 t ha−1 compared to 0.98 and 2 t ha−1 respectively in the control. In conclusion, choosing the appropriate time for intercropping living mulches and selection of plant species (growth and canopy cover) for living mulch are essential in suppressing growth of weeds.
23
Rylander, Haley, Anusuya Rangarajan, Ryan M. Maher, Mark G. Hutton, Nicholas W. Rowley, Margaret T. McGrath e Zachary F. Sexton. "Black Plastic Tarps Advance Organic Reduced Tillage I: Impact on Soils, Weed Seed Survival, and Crop Residue". HortScience 55, n. 6 (giugno 2020): 819–25. http://dx.doi.org/10.21273/hortsci14792-19.
Testo completoAbstract (sommario):
Intensive tillage degrades soil structure, decreases soil organic matter, and can cause soil compaction and erosion over time. Organic vegetable farmers are often dependent on tillage to incorporate crop residue, control weeds, and prepare seedbeds. Black, impermeable, polyethylene tarps applied on the soil surface and removed at planting can help suppress weeds before planting and reduce farmers’ reliance on tillage. However, little is known about how black tarps affect planting conditions and how they can be used to advance reduced tillage production systems. This study investigated the effects of tarp use and tarp duration on the soil environment, surface cover crop residue, and weed suppression to assess the efficacy of using tarps to improve reduced- and no-till practices for organic vegetable production. Experiments were conducted at three sites in the northeastern United States (Freeville, NY; Riverhead, NY; and Monmouth, ME) for 2 years. Following the termination of an oat cover crop, tarps were applied over untilled soils and left in place for four time periods: untarped (control), 3 to 5 weeks (short), 6 to 8 weeks (mid), and 10 or more weeks (long) before two removal dates. Soil moisture and temperature, cover crop residue, soil inorganic nitrogen, weed seed survival, and weed percent cover were measured after tarp removal. Soil moisture and temperature were generally higher under tarps at the time of removal compared with untarped areas at 10% to 55% and 1 to 3 °C, respectively, but the effects were inconsistent. Tarps significantly increased soil nitrate concentrations by 2-times to 21-times with longer tarp durations, resulting in higher concentrations compared with untarped controls. Tarps did not affect the amount of soil covered by cover crop residue and had no consistent effects on weed seed survival of Amaranthus powellii S. Wats. or Chenopodium album L., two common annual weed species in the Northeast. Tarping for at least 3 weeks reduced the weed percent cover by 95% to 100% at the time of removal. Increasing tarp duration beyond 3 weeks did not affect any measures except soil nitrate concentrations. These results indicate that tarps can facilitate the use of reduced-till and no-till practices for organic vegetables by creating a nutrient-rich and moist soil environment free of emerged weeds before planting without soil disturbance.
24
Norsworthy, Jason K., Jeremy K. Green, Tom Barber, Trent L. Roberts e Michael J. Walsh. "Seed destruction of weeds in southern US crops using heat and narrow-windrow burning". Weed Technology 34, n. 4 (30 marzo 2020): 589–96. http://dx.doi.org/10.1017/wet.2020.36.
Testo completoAbstract (sommario):
AbstractNarrow-windrow burning has been a successful form of harvest weed seed control in Australian cropping systems, but little is known about the efficacy of narrow-windrow burning on weed seeds infesting U.S. cropping systems. An experiment was conducted using a high-fire kiln that exposed various grass and broadleaf weed seeds to temperatures of 200, 300, 400, 500, and 600 C for 20, 40, 60, and 80 s to determine the temperature and time needed to kill weed seeds. Weeds evaluated included Italian ryegrass, barnyardgrass, johnsongrass, sicklepod, Palmer amaranth, prickly sida, velvetleaf, pitted morningglory, and hemp sesbania. Two field experiments were also conducted over consecutive growing seasons, with the first experiment aimed at determining the amount of heat produced during burning of narrow windrows of soybean harvest residues (chaff and straw) and the effect of this heat on weed seed mortality. The second field experiment aimed to determine the effect of wind speed on the duration and intensity of burning narrow windrows of soybean harvest residues. Following exposure to the highest temperature and longest duration in the kiln, only sicklepod showed any survival (<1% average); however, in most cases, the seeds were completely destroyed (ash). A heat index of only 22,600 was needed to kill all seeds of Palmer amaranth, barnyardgrass, and Italian ryegrass. In the field, all seeds of the evaluated weed species were completely destroyed by narrow-windrow burning of 1.08 to 1.95 kg m−2 of soybean residues. The burn duration of the soybean harvest residues declined as wind speed increased. Findings from the kiln and field experiments show that complete kill is likely for weed seeds concentrated into narrow windrows of burned soybean residues. Given the low cost of implementation of narrow-windrow burning and the seed kill efficacy on various weed species, this strategy may be an attractive option for destroying weed seed.
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Jitsuyama, Yutaka, e Shinji Ichikawa. "Possible Weed Establishment Control by Applying Cryogens to Fields Before Snowfalls". Weed Technology 25, n. 3 (settembre 2011): 454–58. http://dx.doi.org/10.1614/wt-d-09-00073.1.
Testo completoAbstract (sommario):
Cryogens are defined as substances that produce low temperatures. In this study, cryogens refer to salts added to snow or ice to cool underlying soil, resulting in reduced weed establishment. In laboratory experiments, bags of ice mixed with cryogens were able to reach temperatures as low as −17 C. In soil-filled pots stored at 4 C, bags of cryogenic salts filled with ice chips reduced the soil temperatures to below 0 C and reduced the establishment of weeds significantly without salinity effects. The cryogen magnesium chloride-6-hydrate (MC) that was effective in pot experiments was tested in an oat field in 2008 and 2009. Plastic bags containing concentrated solutions of MC, perforated at the top, were placed on bare soil just before snowfall. Contact of snow with MC was expected to decrease the surface soil temperature enough to cause freezing injury to seeds in the soil. Although overall effects on weed establishment were small, the cryogenic effect did significantly reduce corn spurry establishment in 2008, and significantly reduced overall weed establishment in both years. These results show that weed management with cryogenic salts is possible in principle, but requires further technical improvements to be practical in the field.
26
Conklin, Katie L., e Rodney G. Lym. "Effect of Temperature and Moisture on Aminocyclopyrachlor Soil Half-Life". Weed Technology 27, n. 3 (settembre 2013): 552–56. http://dx.doi.org/10.1614/wt-d-12-00147.1.
Testo completoAbstract (sommario):
Aminocyclopyrachlor will control a variety of invasive weeds but may injure sensitive plant species if seeded into treated soil too soon after application. Aminocyclopyrachlor 50% dissipation time (DT50) ranged from 3 to > 112 d in four soils from the Northern Great Plains. The DT50was dependent on several factors including soil type, moisture content, and temperature. Across four different soil textures, aminocyclopyrachlor dissipation generally increased as soil moisture content increased, but moisture had less of an impact in sandy soils. Aminocyclopyrachlor dissipation also increased as temperature increased in the four soils. The most rapid dissipation occurred in soils with higher clay content, which also had the highest organic matter content of the soils evaluated, and an average DT50of less than 20 d. Seeding sensitive pasture, range, or crop species after aminocyclopyrachlor applications should be done with caution since the herbicide has potential for long persistence in the soil.
27
Taira, T., M. Asai, T. Shibuya e Y. Yogo. "Effect of temperature and buried periods under submerged soil condition on germination ability of annual upland weeds". Journal of Weed Science and Technology 50, Supplement (2005): 76–77. http://dx.doi.org/10.3719/weed.50.supplement_76.
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28
Gill, J., C. Laguë, N. Lehoux, G. Péloquin, J. Coulombe e S. Yelle. "Propane Burner Characterization for Thermal Weeding". HortScience 30, n. 4 (luglio 1995): 819E—819. http://dx.doi.org/10.21273/hortsci.30.4.819e.
Testo completoAbstract (sommario):
To develop new alternatives to chemical pesticides in agriculture, a research program was elaborated on the use of propane flamers for weed control. One part of this project is the evaluation of different propane burners commercially available. We measured the temperature distribution within the burner flames and the fuel consumption of three different types of burner. Flame characterization allowed for the selection of appropriate burners and settings for specific applications. We also investigated the effect of preemergence thermal weeding on crop establishment for 10 different crops. The use of flaming in preemergence of crops is an effective method for controlling weeds, especially for younger and broadleaf weeds. Depending on the crop, thermal weeding can affect the emergence rate when applied just before seedling emergence.
29
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.
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30
SEMB, K. "Growth characteristics of spring barley and selected weeds. II. Effect of temperature and irradiance in growth chambers". Weed Research 36, n. 4 (agosto 1996): 353–67. http://dx.doi.org/10.1111/j.1365-3180.1996.tb01665.x.
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31
Wallace, Rebekah D., Timothy L. Grey, Theodore M. Webster e William K. Vencill. "Increased Purple Nutsedge (Cyperus rotundus) Tuber Sprouting with Diurnally Fluctuating Temperatures". Weed Science 61, n. 1 (marzo 2013): 126–30. http://dx.doi.org/10.1614/ws-d-12-00055.1.
Testo completoAbstract (sommario):
Purple nutsedge is among the most troublesome weeds of vegetables in the Southeast US and a substantial impediment in the search for methyl bromide alternatives. Greater understanding of the environmental cues that regulate tuber sprouting may assist in improved nutsedge management. Experiments were conducted to evaluate the effect of diurnal temperature variation on sprouting of purple nutsedge tubers. Two temperature regimes were evaluated: the first averaged 28 C, with daily fluctuations ranging from 0 to 19.5 C; the second temperature regime averaged 16 C, with daily fluctuations ranging from 0 to 18.5 C. When average temperature was 28 C, cumulative tuber sprouting ranged from 88 to 92%, with no detectable differences among diurnal fluctuations. The high average temperature in the first study may have negated any type of enforced sprouting suppression. However, when average temperature was lowered to 16 C (simulating early spring diurnal fluctuations under polyethylene mulch), there was a positive linear correlation between maximum tuber sprouting and temperature variation. With an average temperature of 16 C, the absence of temperature variation resulted in 52% purple nutsedge sprouting, while 87% sprouting occurred when daily temperature varied 18.5 C at the same average temperature. The use of various types of mulching material can affect average soil temperatures and diurnal variations, potentially shifting nutsedge emergence. Further studies are needed to determine if these data on tuber sprouting in response to alternating temperatures can facilitate more efficient weed management.
32
Potvin, Catherine, e Boyd R. Strain. "Effects of CO2 enrichment and temperature on growth in two C4 weeds, Echinochloa crus-galli and Eleusine indica". Canadian Journal of Botany 63, n. 9 (1 settembre 1985): 1495–99. http://dx.doi.org/10.1139/b85-206.
Testo completoAbstract (sommario):
Mathematical growth analyses were carried out on two C4 grasses, Echinochloa crus-galli and Eleusine indica, to test the influence of CO2 enrichment and temperature on growth. Echinochloa populations from Québec, North Carolina, and Mississippi and a single population of Eleusine from Mississippi were grown for 48 days at two CO2 concentrations (350 and 675 μL∙L−1) and three temperature regimes (28:22, 24:18, and 21:15 °C). CO2 enrichment generated an increased root dry weight and induced an earlier development of inflorescences. Net assimilation rate, the only other parameter to respond to CO2 enrichment, was higher for plants grown at high CO2 concentrations during the first harvest interval. Biomass partitioning was affected by temperature. Root dry weight was greater in plants grown at 21:15 °C while more leaf area was produced in warmer temperature regimes. Only plants from Québec maintained normal growth rates under the 21:15 °C regime, suggesting that northern C4 plants are better suited for growth at low temperatures than southern ones.
33
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.
34
Korres, Nicholas E., e Franck E. Dayan. "Effects of Climate Change on Crops and Weeds: The Need for Climate-smart Adaptation Paradigm". Outlooks on Pest Management 31, n. 5 (1 ottobre 2020): 210–15. http://dx.doi.org/10.1564/v31_oct_04.
Testo completoAbstract (sommario):
The net effect of climate change on agriculture is likely to be negative despite the potential beneficial effects some crops and regions might receive. While increases in atmospheric CO2 are projected to stimulate growth in C3 crops and improve water use efficiency in C4 crops, climate impacts, particularly temperature increase, heat waves, droughts and flooding, will probably reduce yield potential. These negative effects will be compounded by increased weed interference and competition with the crop. The new type of "carbon farmer" should adapt to climate change and implement farming practices that focus on agricultural production models that mitigate climate change and promote "nature" and sustainability. Everything is already at least possible in one form or another, and the challenge is now to make it a reality.
35
Nussbaum, Emily S., Allen F. Wiese, Donald E. Crutchfield, Ellis W. Chenault e Dwane Lavake. "The Effects of Temperature and Rainfall on Emergence and Growth of Eight Weeds". Weed Science 33, n. 2 (marzo 1985): 165–70. http://dx.doi.org/10.1017/s0043174500082035.
Testo completoAbstract (sommario):
From 1976 to 1981, emergence date, height, and dry weight per plant were taken for eight weed species grown at Bushland, TX, at two stand densities. Height and dry weight per plant were related to precipitation and degree-days for air and soil temperatures using base temperatures of 10, 15.5, or 21 C. Kochia [Kochia scoparia(L.) Schrad. ♯ KCHSC] emerged early in March and was followed by poison suckleya [Suckleya suckleyana(Torr.) Rydb. ♯ SUKSU], sunflower (Helianthus annuusL. ♯ HELAN), and common cocklebur (Xanthium pensylvanicumWallr. ♯ XANPE) in early April. Buffalobu(Solanum rostratumDunal. ♯ SOLCU), puncturevine (Tribulus terrestrisL. ♯ TRBTE), lanceleaf sage (Salvia reflexaHornem. ♯SALRE), and barnyardgrass (Echinochloa crus-galliL. Beauv. ♯ECHCG) emerged in late April. The weeds began to increase in height during May but plants did not start increasing in weight until June. Kochia, common cocklebur, and sunflower grew tallest, produced most dry matter, made most efficient use of water, and weighed most per plant. Heat unit accumulations were strongly correlated with plant height.
36
Kitiş, Yasin Emre, Onur Kolören e Feyzullah Nezihi Uygur. "Yeni Tesis Mandalina Bahçesinde Malç Tekstili Uygulamasının Yabancı Ot Kontrolü ve Mandalina Gelişimine Etkileri". Turkish Journal of Agriculture - Food Science and Technology 5, n. 6 (12 luglio 2017): 568. http://dx.doi.org/10.24925/turjaf.v5i6.568-580.729.
Testo completoAbstract (sommario):
In this study, material that we call mulch textile was investigated as compared with conventional polyethylene mulch nylon and mechanical and chemical control that are widely used in farmer’s conditions to weed control in newly established citrus orchards. Two different thickness of polyethylene mulch, three different thickness of mulch textiles, mowing and herbicide (glyphosate) applications were made in newly established mandarin orchard in a three-year-period (2004-2005-2006). Effects of the applications on density and coverage of weeds and height, stem thickness and leaf area of cultural plants were investigated. According to general evaluation of results of the study, mowing 23.4%, chemical control 88.4%, polyethylene mulch 99.6%, mulch textiles 100% controlled weeds than weedy control. At the most increase of height, stem thickness and leaf area of mandarin was obtained from herbicide and mulch treatments. It was determined that soil temperature and moisture are preserved by mulch applications.
37
Ali Al-Shebly, Hayder Azeez. "Effect of Aspergillus flavus on Seed Germination and Seedlings Growth of Barley and Some of Associated Weeds". IOP Conference Series: Earth and Environmental Science 1060, n. 1 (1 luglio 2022): 012119. http://dx.doi.org/10.1088/1755-1315/1060/1/012119.
Testo completoAbstract (sommario):
Abstract The research was conducted during the 2021 growing season which included a series of experiments to investigate the effect the fungus Aspergillus flavus presence on germination and growth of barley and some barley weeds including annual ryegrass Lolium rigidum, darnel Lolium temulentum and yellow sweet clover Melilotus officinalis. Results of isolation and identification of fungi associated with seedlings roots of barley and the weeds showed that A. flavus was the most prevalent fungus associated with roots and surrounding soil recording the highest frequency among all the found fungi. In plastic pots, Aspergillus flavus was added to the potting soil and tested for its the effect on seed germination and seedlings growth of barley and weeds under study. The results showed after 20 days of planting that the fungus led to an increase in the percentage of germination and fresh weight and lengths of barley seedlings while the presence of the fungus decreased germination and seedlings growth of studied weeds with the highest negative impact on the darnel. Incubation at different temperatures were tested for their effects on A. flavus growth, and results showed that the fungus grows higher when incubated at relatively high temperatures (25-35°C), while the lowest growth was at 15 °C and the fungus did not grow at 10 °C.
38
Scherner, Ananda, Bo Melander, Peter K. Jensen, Per Kudsk e Luis A. Avila. "Germination of Winter Annual Grass Weeds under a Range of Temperatures and Water Potentials". Weed Science 65, n. 4 (8 maggio 2017): 468–78. http://dx.doi.org/10.1017/wsc.2017.7.
Testo completoAbstract (sommario):
Silky windgrass and annual bluegrass are among the most troublesome weeds in northern European winter crops, while problems with rattail fescue have been especially linked to direct-drilling practices. This study investigated the germination patterns of silky windgrass, annual bluegrass, and rattail fescue in multiple water potentials and temperature regimes. Temperature and water potential effects were similar between silky windgrass and rattail fescue, but differed from annual bluegrass. The three grass weeds were able to germinate under low water potential (−1.0 MPa), although water potentials ≤−0.25 MPa strongly delayed their germination. Silky windgrass and rattail fescue seeds were able to germinate at 1 C, while the minimum temperature for annual bluegrass germination was 5 C. Germination of silky windgrass and rattail fescue was very similar across temperature and water potentials, which implies similar emergence flushes under field conditions, allowing management interventions to follow the same scheme.
39
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.
40
Matsuo, Kazuyuki, e Tetsuo Kubota. "Effects of Stratification and Temperature on Germination of Annual Upland Weeds in Tohoku District." Journal of Weed Science and Technology 38, n. 2 (1993): 90–96. http://dx.doi.org/10.3719/weed.38.90.
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41
Kostyuk, A. V., e N. G. Lukacheva. "THE EFFECIENCY OF LEAF EFFECT HERBICIDES FOR CORN CROPS". Siberian Herald of Agricultural Science 48, n. 4 (23 ottobre 2018): 20–26. http://dx.doi.org/10.26898/0370-8799-2018-4-3.
Testo completoAbstract (sommario):
The efficiency of leaf effect herbicides in corn crops was studied. The study was carried out in 2001–2016 in the experimental fields of Primorye on brown meadow podzolized soils containing 3-4% of humus in the arable horizon. In 2001–2010 corn of hybrid population Slavyanka was sown and in 2015–2016 – ZPTK196, with a seeding rate of 70.000 seeds/ha. Herbicides Milagro (1.0 and 1.5 l/ha), Titus (0.04 kg/ha), Cordus (0.04 kg/ ha) and Doublon Gold (0.07 kg/ha) in tank mixture with Luvaram (0.82 l/ha) or Dianatom (0.4 l/ ha) enhanced the effect of preparations on weed plants, especially on common ragweed (Ambrosia artemisiifolia). Biological efficiency increased to 74–90%, and yield – by 0.43–1.80 t/ha. The use of herbicide Basis (0.02 and 0.025 kg/ha) led to the increase in corn grain yield to 1.43–2.06 t/ ha. Resistant to this herbicide was dayflower (Commelina communis), which, due to the lack of other weeds, increased the above-ground mass to 1.3 kg / m2.. The application of herbicide MaisTer provided the yield increase up to 2.09–2.41 t/ha. It was observed that for more reliable suppression of common ragweed, herbicide MaisTer (0.125 and 0.15 kg/ha) should be used no later than the phase of three pairs of leaves when the air temperature does not exceed 200C. The herbicides Titus Plus (0.34 and 0.38 kg/ha) and Stellar (1.5l/ ha) almost completely purified the corn from weeds, which contributed to the preservation of 2.07–3.59 t/ha of corn.
42
Ruttledge, Annemieke, Ralph D. B. Whalley, Gregory Falzon, David Backhouse e Brian M. Sindel. "The role of soil temperature and seed dormancy in the creation and maintenance of persistent seed banks of Nassella trichotoma (serrated tussock) on the Northern Tablelands of New South Wales". Rangeland Journal 42, n. 2 (2020): 85. http://dx.doi.org/10.1071/rj20008.
Testo completoAbstract (sommario):
A large and persistent soil seed bank characterises many important grass weeds, including Nassella trichotoma (Nees) Hack. ex Arechav. (serrated tussock), a major weed in Australia and other countries. In the present study we examined the effects of constant and alternating temperatures in regulating primary and secondary dormancy and the creation and maintenance of its soil seed bank in northern NSW, Australia. One-month-old seeds were stored at 4, 25°C, 40/10°C and 40°C, in a laboratory, and germination tests were conducted every two weeks. Few seeds germinated following storage at 4°C, compared with seeds stored at 25°C, 40/10°C and 40°C. Nylon bags containing freshly harvested seeds were buried among N. trichotoma stands in early summer, and germination tests conducted following exhumation after each season over the next 12 months. Seeds buried over summer and summer plus autumn had higher germination than seeds buried over summer plus autumn plus winter, but germination increased again in the subsequent spring. Seeds stored for zero, three, six and 12 months at laboratory temperatures were placed on a thermogradient plate with 81 temperature combinations, followed by incubation at constant 25°C of un-germinated seeds. Constant high or low temperatures prolonged primary dormancy or induced secondary dormancy whereas alternating temperatures tended to break dormancy. Few temperature combinations resulted in more than 80% germination.
43
Martelloni, Luisa, Christian Frasconi, Mino Sportelli, Marco Fontanelli, Michele Raffaelli e Andrea Peruzzi. "The Use of Different Hot Foam Doses for Weed Control". Agronomy 9, n. 9 (28 agosto 2019): 490. http://dx.doi.org/10.3390/agronomy9090490.
Testo completoAbstract (sommario):
Thermal weed control technology plays an important role in managing weeds in synthetic herbicide-free systems, particularly in organic agriculture. The use of hot foam represents an evolution of the hot water weed control thermal method, modified by the addition of biodegradable foaming agents. The aim of this study was to test the weeding effect of different five hot foam doses, in two sites of different weed composition fields [i.e., Festuca arundinacea (Schreb.), Taraxacum officinale (Weber) and Plantago lanceolata (L.)], by evaluating the devitalisation of weeds, their regrowth, the weed dry biomass at the end of the experiment and the temperature of hot foam as affected by different foam doses. The results showed that the effect of the hot foam doses differed with the different infested weed species experiments. In the Festuca arundinacea (Schreb.) infested field, all doses from 3.33 L m−2 to 8.33 L m−2 led to a 100% weed cover devitalisation and a lower weed dry biomass compared to the dose of 1.67 L m−2, whereas the weed regrowth was similar when all doses were applied. In the Taraxacum officinale (Weber) and Plantago lanceolata (L.) infested fields, doses from 5.00 L m−2 to 8.33 L m−2 in site I and from 3.33 L m−2 to 8.33 L m−2 in site II led to 100% of weed cover devitalisation. The highest doses of 6.67 L m−2 and 8.33 L m−2 led to a slower weed regrowth and a lower weed dry biomass compared to the other doses. The time needed for weeds to again cover 50%, after the 100% devitalisation, was, on average, one month when all doses were applied in the Festuca arundinacea (Schreb.) infested field, whereas in the Taraxacum officinale (Weber) and Plantago lanceolata (L.) fields, this delay was estimated only when doses of 6.67 L m−2 and 8.33 L m−2 were used in site I and a dose of 8.33 L m−2 in site II. Thus, in the Festuca arundinacea (Schreb.) field experiments hot foam doses from 3.33 L m−2 to 8.33 L m−2 were effective in controlling weeds, and the use of the lowest dose (i.e., 3.33 L m−2) is recommended. However, for Taraxacum officinale (Weber) and Plantago lanceolata (L.) the highest doses are recommended (i.e., 6.67 L m−2 and 8.33 L m−2), as these led to 100% weed devitalisation, slower regrowth, and lower weed dry biomass than other doses. A delay in the regrowth of weeds by 30 days can lead to the hypothesis that the future application of hot foam as a desiccant in no-till field bands, before the transplant of high-income vegetable crops, will provide a competitive advantage against weeds.
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Kashiyama, Tadayoshi, Shigetaka Okano e Masahito Mochizuki. "Effect of Process Variable on Temperature Distribution in the Heat-Affected Zone of Temper Bead Welds". QUARTERLY JOURNAL OF THE JAPAN WELDING SOCIETY 35, n. 2 (2017): 13s—17s. http://dx.doi.org/10.2207/qjjws.35.13s.
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Brown, Bryan, e Eric R. Gallandt. "A Systems Comparison of Contrasting Organic Weed Management Strategies". Weed Science 66, n. 1 (2 agosto 2017): 109–20. http://dx.doi.org/10.1017/wsc.2017.34.
Testo completoAbstract (sommario):
Weed management strategies differ in their ability to control weeds, and often have unique agroecological implications. To provide growers with an improved sense of trade-offs between weed control and ecological effects, we implemented several prominent organic weed management strategies in yellow onion in 2014 and 2015. Strategies included cultivation of weed seedlings during the early, weed-sensitive “critical period” of the crop; frequent cultivation events to ensure “zero seed rain”; and weed suppression with polyethylene or natural mulches. As expected, end-of-season weed biomass and weed seed production were greatest in the critical period system and nearly zero for the zero seed rain system. Weeds were also well controlled in natural mulch systems. Average onion yield per treatment was 50.7 Mg ha−1. In 2014, the critical period system and the polyethylene mulch systems demonstrated yield loss, likely due to weed competition and excessive soil temperature, respectively. Onion soluble solids content was also diminished in these systems in 2014, but bulb firmness was greatest in unmulched systems. Carabid beetles, earthworms, soil compaction, soil nitrate, and microbial biomass were affected by weed management strategy, with natural-mulched systems generally performing most favorably. However, these effects were not substantial enough to affect yield of a subsequent sweet corn crop grown in weed-free conditions. In contrast, sweet corn managed with only early-season cultivations demonstrated yield loss (P=0.004) in plots where the critical period treatment was implemented the prior year, indicating that weed competition resulting from abundant weed seed production in that system was the most influential legacy effect of the weed management strategies.
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Agusta, H., D. Guntoro, B. Arifin, M. Syakir e M. B. Yunindanova. "Rice Waste Hydrolyzation at Subcritical Temperature to Produce Bioherbicide to Control Terrestrial Weeds". IOP Conference Series: Earth and Environmental Science 950, n. 1 (1 gennaio 2022): 012030. http://dx.doi.org/10.1088/1755-1315/950/1/012030.
Testo completoAbstract (sommario):
Abstract Thermal anaerobic hydrolyzation process on rice husk with higher lignin content produced organic complexes constituents including phenolic groups. Phenolic groups expose herbicide effects on growing vegetations, where the process in nature mainly require anaerobic condition. The degradation rate in nature is very slow with very low concentration availability. Thermal hydrolyzation is an appropriate choice to produce phenolics herbicide for sustainable pesticide management and application. This study aimed to identify the potency of rice husk extract by thermal hydrolyzation process as an organic herbicide to control terrestrial weeds. The hydrolyzation was processed in 60-90 bars and 280±20 °C for 30±10 minutes. The existence of the phenolic groups in the hydrolysate was considered for generic active ingredients to control weed in the terrestrial ecosystem. Its damage impact was tested on Borreria alata, Eleusine indica, Cyperus kyllingia, Paspalum conjugatum, Asystasia intrusa, and Axonopus compressus. The assay covered the growth at pre-emergence, early post-emergence, and post-emergence growing stages. The rice waste hydrolysate was capable to suppress the growth of the weed growth especially at the pre-emergence stage at 30-64%, and at early post-emergence stages at the suppressing rate of 77-100%. However, the suppressing affectivity is lower at the post-emergence stage which only 17-25%.
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Monnig, Nicholas, Thomas L. Clark, Wayne C. Bailey e Kevin W. Bradley. "Impact of Fall and Early Spring Herbicide Applications on Insect Injury and Soil Conditions in No-Till Corn". Weed Technology 21, n. 4 (dicembre 2007): 1002–9. http://dx.doi.org/10.1614/wt-06-192.1.
Testo completoAbstract (sommario):
Field studies were established at two Missouri locations in 2004 and 2005 to evaluate the effects of fall and early spring herbicide applications on soil temperature, soil moisture content, and insect injury in no-till corn production systems. Both experiments received applications of simazine plus 2,4-D, rimsulfuron plus thifensulfuron plus 2,4-D, and glyphosate plus 2,4-D in the fall, 45 d prior to planting (45 d EPP), 30 d prior to planting (30 d EPP), and 7 d prior to planting (7 d EPP). During a period from April 1 to April 14, simazine plus 2,4-D applied 45 d EPP resulted in higher soil temperatures at a 5-cm depth compared to the untreated control. However, there were few differences in soil temperature present from April 15 to May 1. Soil moisture readings taken during this same time period correlated with soil temperature readings. Measurements of soil moisture taken at 1 and 3 wk after planting (WAP) revealed significantly lower soil moisture readings in the untreated compared to herbicide treated plots. This lower soil moisture content allowed untreated plots to warm up more rapidly and thereby eliminated any negative impacts that dense stands of winter annual weeds may have had on soil temperature. Evaluations of corn flea beetle and lepidopteron injury taken at the V2, V4, and V6 corn leaf stages revealed significant differences in injury as a result of these treatments. When dense stands of winter and summer annual weeds were left uncontrolled, corn flea beetle injury was significantly lower than in plots treated with a herbicide. However, when a post herbicide application was made to remove all weed species prior to the V6 sampling date, differences in corn flea beetle injury between the untreated and herbicide treated plots were eliminated. Additionally, removal of all weed species led to higher lepidopteron injury in the untreated.
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Vleeshouwers, L. M. "Modelling the Effect of Temperature, Soil Penetration Resistance, Burial Depth and Seed Weight on Pre-emergence Growth of Weeds". Annals of Botany 79, n. 5 (1 maggio 1997): 553–63. http://dx.doi.org/10.1006/anbo/79.5.553.
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Sharpe, Shaun M., Nathan S. Boyd, Peter J. Dittmar, Greg E. MacDonald e Rebecca L. Darnell. "Effect of Temperature on Clopyralid Safety in Strawberry". Weed Technology 32, n. 3 (2 febbraio 2018): 347–51. http://dx.doi.org/10.1017/wet.2017.119.
Testo completoAbstract (sommario):
AbstractStrawberry is an important horticultural crop in Florida. The long growing season and escapes from fumigation and PRE herbicides necessitate POST weed management to maximize harvest potential and efficiency. Alternatives to hand-weeding are desirable, but clopyralid is the only broadleaf herbicide registered for use. Weed control may be improved by early-season clopyralid applications, but at risk of high temperature and increased strawberry injury. The effect of temperature on clopyralid safety on strawberry is unknown. We undertook a growth chamber experiment using a completely randomized design to determine crop safety under various temperature conditions across acclimation, herbicide application, and post-application periods. There was no effect of clopyralid on the number of strawberry leaves across all temperatures. Damage to the strawberry manifested as leaf malformations. Acclimation temperatures affected clopyralid-associated injury (p=0.0309), with increased leaf malformations at higher temperatures (27 C) compared to lower (18 C) temperatures. Pre-treatment temperatures did not affect clopyralid injury. Post-application temperature also affected clopyralid injury (p=0.0161), with increased leaf malformations at higher temperatures compared to lower ones. Clopyralid application did not reduce flowering or biomass production in the growth chamber. If leaf malformations are to be avoided, consideration to growing conditions prior to application is advisable, especially if applying clopyralid early in the season.
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NEGREIROS, ANDRÉIA MITSA PAIVA, NAAMA JÉSSICA DE ASSIS MELO, MÁRCIA MICHELLE DE QUEIROZ AMBRÓSIO, GLAUBER HENRIQUE DE SOUSA NUNES e RUI SALES JÚNIOR. "GROWTH RATE, PATHOGENICITY AND FUNGICIDE SENSITIVITY OF Macrophomina spp. FROM WEEDS, MELON AND WATERMELON ROOTS". Revista Caatinga 35, n. 3 (settembre 2022): 537–47. http://dx.doi.org/10.1590/1983-21252022v35n304rc.
Testo completoAbstract (sommario):
ABSTRACT Macrophomina (Botryosphaeriaceae) is one of the main genera of soilborne phytopathogenic fungi, which causes root and seed rot in more than 800 host plants worldwide. Recent phylogenetic studies identified the species M. phaseolina and M. pseudophaseolina in Trianthema portulacastrum and Boerhavia diffusa in melon and watermelon production areas in northeastern Brazil. Therefore, the objective of this study was: i) to verify the effect of temperature and salinity on the mycelial growth of M. phaseolina, M. pseudophaseolina and M. euphorbiicola, ii) to assess their pathogenicity on melon and watermelon seedlings, and iii) to determine their sensitivity to the fungicide carbendazim. The optimal temperature for mycelial growth rate (MGR) for Macrophomina spp. ranged from 27.18 ºC (CMM4771 – M. pseudophaseolina) to 31.80 ºC (CMM4763 – M. phaseolina). For the effect of salinity on mycelial growth of Macrophomina isolates, the EC50 ranged from 103.76 (CMM4868 – M. euphorbiicola) to 315.25 mM (CMM4801 – M. pseudophaseolina). The pathogenicity test demonstrated that M. phaseolina, M. pseudophaseolina and M. euphorbiicola are pathogenic on melon with M. phaseolina exhibiting a higher level of virulence. Macrophomina euphorbiicola isolates did not cause disease in watermelon. The most sensitive isolates to the fungicide carbendazim were CMM4868, CMM4867 (M. euphorbiicola) and CMM1531 (M. phaseolina) with EC50 of 0.003, 0.012 and 0.012 mg.L-1 a.i., respectively. All Macrophomina spp. used in these experiments were pathogenic to the tested melon and watermelon cultivars with the exception of the M. euphorbiicola isolate that did not cause damage to watermelon.