Letteratura scientifica selezionata sul tema "Effect of chemicals on weeds"
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Articoli di riviste sul tema "Effect of chemicals on weeds"
1
Roberts, Warren, Jim Shrefler, Jim Duthie, Jonathan Edelson e Wes Watkins. "Watermelon Weed Control: Current and Future Possibilities". HortScience 32, n. 3 (giugno 1997): 428E—428. http://dx.doi.org/10.21273/hortsci.32.3.428e.
Testo completoAbstract (sommario):
Watermelon is the major fresh-market vegetable grown in Oklahoma, but growers have few labeled herbicides from which to choose. Grower surveys in Oklahoma have identified weed control as the major production problem facing watermelon producers. In 1995 and 1996, various mechanical and chemical weed control strategies have been explored. `Allsweet' watermelons were grown with various combinations of labeled and unlabeled herbicides, as well as mechanical control treatments. Treatments included bensulide, clomazone, DCPA, ethalfluralin, glyphosate, halosulfuron, napropamide, naptalam, paraquat, pendimethalin sethoxydim, and trifluralin. Certain chemicals were used in combination. Paraquat and glyphosate were used as wipe-on materials. Glyphosate and paraquat could not be applied until weeds were taller than the watermelon foliage, causing serious weed competition. In general, superior results were obtained from hand-weeded plots, trifluralin, and DCPA. Halosulfuron gave superior control of broadleaf weeds, but had a negligible effect on grasses. Napropamide gave good control of grasses and broadleaf weeds other than solanaceous weeds. No chemical, when used alone, gave satisfactory control throughout the growing season. Early cultivation, followed by chemical application at layby, appears to be one of the better treatments.
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Vaczkó, Gábor, László Hódi, Melinda Tar, Péter Jakab e István Kristó. "The effect of different weed control technologies on weed species composition of maize". Review on Agriculture and Rural Development 7, n. 1-2 (1 novembre 2019): 67–71. http://dx.doi.org/10.14232/rard.2018.1-2.67-71.
Testo completoAbstract (sommario):
In our investigation we used different weed control technologies in the different phenology states of the maize. The farm experiment has been carried out in Hungary, Kunágota, on flat surface, homogeneous quality chernozem soil, on 1000 m2 plots, in 4 replications.
The experiment can be regarded as 9 weed-control strategies where, in addition to the untreated control, two chemicals are applied (Laudis, Capreno) in different doses, two mechanical weed-control technologies, and two combination of chemicals and mechanicals weed-control technologies were used. Mechanical weed-control place connected to the herbicide treatments in different times: until 4-6-leave age weedless, in 4-6-leave age hoed once, in 4-6-leave age cultivation once.
Our results were assessed by chemical efficiency examination in five periods. Our resoult show that the two tested herbicides were efficient against weeds. Laudis was more effective, than Capreno against Setaria pumila. The dose enlargement of Capreno only slightly increased the herbicidal efficiency. The decreased dosage of Capreno was not efficient enough against Abutilon theophrasti.
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Nwosisi, Nandwani e Hui. "Mulch Treatment Effect on Weed Biomass and Yields of Organic Sweetpotato Cultivars". Agronomy 9, n. 4 (13 aprile 2019): 190. http://dx.doi.org/10.3390/agronomy9040190.
Testo completoAbstract (sommario):
Weeds are a challenge, particularly in organic agriculture, due to restrictions on the application of synthetic herbicides and chemicals. A preliminary cultivar evaluation trial of organic sweetpotato was conducted in 2015 at Tennessee State University certified organic farm. Three mulches: wheat straw, pine needle, and black plastic mulch, along with a control (no mulch), were evaluated for their weed management abilities in a sweetpotato field. Four cultivars of sweetpotato were planted in 0.91 m wide mulch beds with 0.3 m row spacing anddrip irrigated with four replications. Data was collected during the growing season on the dry weight of weeds that emerged in a quadrat and yield components at harvest. Results of two-way ANOVA revealed that mulch treatments affected the weed biomass, weed density, and cull yields. Though the use of mulches had no significant effect on other yield components of sweetpotato in this study; it was beneficial for weed management.
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Batish, D. R., H. P. Singh, D. B. Saxena e R. K. Kohli. "Weed suppressing ability of parthenin a sesquiterpene lactone from Parthenium hysterophorus". New Zealand Plant Protection 55 (1 agosto 2002): 218–21. http://dx.doi.org/10.30843/nzpp.2002.55.3893.
Testo completoAbstract (sommario):
To find alternate chemicals with novel mode of action allelochemicals which are natural plant products are being investigated This study was undertaken to explore the effect of parthenin (chemically a sesquiterpene lactone from Parthenium hysterophorus L) on two weed species viz Amaranthus viridis and Chenopodium murale In a laboratory bioassay germination seedling growth and dry weight accumulation of the weeds were significantly reduced by treating with parthenin The chlorophyll content and the respiratory activity were also significantly affected in the treated plants The study concluded that phytotoxicity of parthenin could be useful as a natural herbicide for future weed management programmes
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ADETUNJI, Charles Oluwaseun, Julius Kola OLOKE, Gandham S. PRASAD e Isaac Oluseun ADEJUMO. "Effect of Lasiodiplodia pseudotheobromae Isolates, a Potential Bioherbicide for Amaranthus hybridus L. in Maize Culture". Notulae Scientia Biologicae 9, n. 1 (30 marzo 2017): 131–37. http://dx.doi.org/10.15835/nsb9110018.
Testo completoAbstract (sommario):
The use of phytopathogenic fungi in biological control of weeds may represent a promising alternative to the use of chemicals and may lead to the sustainability of agro-ecosystems. In the current study, strain C1136 was developed into various formulations and their activities were compared with a chemical herbicides using glyphosate in a screen house, applying standard procedure. All the bioherbicide treatments gave significantly higher yield component on the following parameters: tasselling, number of cobs, day of silking, number of ears, number of grain/cob, weight of 100 grains, number of cob, weight of cob, and length of cob from maize when compared to the chemical-treated herbicides and weedy cheek. Moreover, the bioherbicidal formulation coded BH4 (32 g of semolina + 6 g kaolin + 20 mL of glycerol + mutant strain of Lasiodiplodia pseudotheobromae + glucose+ sucrose + fructose + dextrose + lactose sugar + peptone) showed the highest activities when compared to other formulations. Conclusively, this study revealed that Lasiodiplodia pseudotheobromae C1136 strain has bioherbicidal activity and could therefore be exploited for large scale production of bioherbicides for weed control in conventional farming, to improve yield and enhance food security.
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Gavryushina, I. V., S. A. Semina e S. M. Nadezhkin. "GROWING CONDITIONS INFLUENCE ON MAIZE CROPS PHYTOSANITARY STATE". Scientific Life 15, n. 9 (30 settembre 2020): 1215–23. http://dx.doi.org/10.35679/1991-9476-2020-15-9-1215-1223.
Testo completoAbstract (sommario):
An important place in the set of measures aimed at increasing the yield of maize is occupied by the methods of using fertilizers, herbicides and growth regulators. The yield of maize is largely determined by the phytosanitary state of crops. Maize has an average competitiveness and is sensitive to the presence of an excessive amount of weed-field component in agrocenoses. The article presents the results of three-year studies on the use of the pre-emergence herbicide DualGold and the postemergence herbicide Elumisna in various agrophonics, and shows their role in reducing the weediness of crops in the early maturing hybrid of maize Ladoga 181 MB. The possibility of using the growth regulator Zircon using herbicides has been studied. The observations showed that three weeks after the application of the post-emergence herbicide, the combined use of herbicides had a more effective effect on the state of maize crops - the total weediness decreased by 77.3 ... 79.1%. In the same variants, weeds accumulated the smallest dry biomass - 14.4 ... 17.8 g against an unfertilized background and 23.8 ... 25.1 g when applying mineral fertilizers. For harvesting, the greatest biological efficiency was also noted with complex herbicide treatment - 53.7 ... 62.3%. A significant decrease in the dry weight of weeds was established due to chemical weeding: against an unfertilized background by 7.9 ... 9.1 times, with fertilization - by 4.2 ... 6.9 times. The complex application of the growth regulator Zircon with herbicides contributed to a decrease in the number and weight of weeds by the time of harvesting maize, did not increase the adaptation of weeds to the effects of chemicals.
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Mennan, Husrev, e Mathieu Ngouajio. "Effect of Brassica Cover Crops and Hazelnut Husk Mulch on Weed Control in Hazelnut Orchards". HortTechnology 22, n. 1 (febbraio 2012): 99–105. http://dx.doi.org/10.21273/horttech.22.1.99.
Testo completoAbstract (sommario):
Weed management is critical in hazelnut (Corylus avellana) production. Weeds reduce nutrient availability, interfere with tree growth, and reduce hand-harvesting efficiency. Field experiments were conducted from Fall 2006 to 2010 to test effects of brassica (Brassica sp.) cover crops and hazelnut husk mulch as alternative weed management strategies in hazelnut. The cover crop treatments consisted of rape (Brassica napus), field mustard (Brassica rapa), oriental mustard (Brassica juncea), and fallow with no cover crop. Hazelnut husk was surface-applied at two thicknesses, 5- and 10-cm-thick layer. Dry biomass production by the cover crops was relatively consistent among years with oriental mustard producing the most biomass. Throughout the growing seasons, the cover crops reduced weed density, weed dry weight, and the number of weed species when compared with the fallow treatment. The most effective cover crop at suppressing weeds was oriental mustard. Hazelnut husk applied as a 10-cm-thick layer on the ground was highly effective at controlling weeds up to 180 days after application and reduced total weed dry weight by 83% at the end of the season. Our findings indicate that brassica cover crops or hazelnut husk may help control annual weed species in hazelnut orchards during early summer. However, these strategies should be combined with other methods like chemicals or cultivation for adequate weed management.
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Garcia De Arevalo, Rafael C., Carmen A. Lusarreta, Carmen B. Neyra, Mercedes A. Sanchez e Pedro J. H. Algarra. "Chemical Control of Annual Weeds in Field Beans (Vicia faba) in Central Spain". Weed Science 40, n. 1 (marzo 1992): 96–100. http://dx.doi.org/10.1017/s0043174500057027.
Testo completoAbstract (sommario):
Field studies were conducted over 3 yr to investigate the effect of chemicals on field beans density and weed control. Predominant weed species were common lambsquarters, fumitory, henbit, corn poppy, prostrate knotweed, and wild mustard. All herbicide treatments except linuron injured field beans. Mean field beans survival at harvest was 78% in alachlor and 84% in alachlor containing treatments. Only 5% survived atrazine at 1.9 kg ai ha−1. Ethalfluralin, pendimethalin, simazine, terbutylazine plus terbutryn, and trifluralin treatments produced plant survival values of 56, 82, 86, 74, and 71%, respectively. Chemical control of the main weed species overshadowed the detrimental effect on field beans density, and thus most herbicide treatments except alachlor resulted in increased dry beans yield. The best overall results occurred with linuron, simazine, terbuthylazine plus terbutryn, and pendimethalin which increased dry beans yields 76, 63, 56, and 40%, respectively, over the control plots. Common lambsquarters was the dominant weed, and prostrate knotweed and corn poppy were the most difficult and the easiest species to control, respectively.
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Zdražílková, Magda. "Comparison of the seed bank with the aboveground vegetation of field weeds in the neighbourhood of Mikulov in South Moravia". Acta Universitatis Agriculturae et Silviculturae Mendelianae Brunensis 59, n. 1 (2011): 277–90. http://dx.doi.org/10.11118/actaun201159010277.
Testo completoAbstract (sommario):
The processed set of phytosociological relevés indicated that at the present time the field weed associations are composed particularly of species of wide ecological amplitude. The rare and endangered species appeared only on localities usually not much affected by chemicals. Most of the endangered species of field weeds were found to survive primarily on small private farms, in the headland of fields or on field edges near the natural reserves.The results indicated that the type of crop had a significant effect on the composition of the current aboveground vegetation. There is a close relationship between the type of crop and the applied cultural practice. Its effect is much more important than the effect of the overall method of management. However, long-term application of herbicides may eliminate some weed species from the seed bank and as a consequence also from the current vegetation. That is the reason why crop rotation is so important for preserving the species diversity of weeds in tandem with limited applications of herbicides.
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Carrubba, Alessandra, Andrea Labruzzo, Andrea Comparato, Serena Muccilli e Alfio Spina. "Use of Plant Water Extracts for Weed Control in Durum Wheat (Triticum turgidum L. Subsp. durum Desf.)". Agronomy 10, n. 3 (6 marzo 2020): 364. http://dx.doi.org/10.3390/agronomy10030364.
Testo completoAbstract (sommario):
The use of plant water extracts to control weeds is gaining attention in environmentally-friendly agriculture, but the study of the effect that such extracts may exert on the yield of durum wheat is still unexplored. In 2014 and 2016, the herbicidal potential of several plant water extracts was field tested on durum wheat (cv Valbelice). In 2014, extracts obtained from Artemisia arborescens, Rhus coriaria, Lantana camara, Thymus vulgaris, and Euphorbia characias were used, whereas in 2016 only A. arborescens and R. coriaria were tested as “donor” plants. In both years, weed incidence was evaluated, together with the major yield parameters of wheat. None of the treatments (including chemicals) could eradicate weeds from the field. In 2014, dicots were in general prevailing in plots treated with extracts of E. characias, while monocots prevailed after treatments with L. camara and R. coriaria. In 2016, lower weed biomass and diversity level were found, and only Avena and Phalaris were detected at harvest time. Treatment with plant water extracts affected grain yields, but it seems likely that those effects are not due to the diverse incidence of weeds in treated and untreated plots, rather to some direct action exerted by allelopathic substances.
Tesi sul tema "Effect of chemicals on weeds"
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Omami, Elizabeth Nabwile, of Western Sydney Hawkesbury University, of Agriculture Horticulture and Social Ecology Faculty e School of Horticulture. "Amaranthus retroflexus seed dormancy and germination responses to environmental factors and chemical stimulants". THESIS_FAHSE_HOR_Omami_E.xml, 1993. http://handle.uws.edu.au:8081/1959.7/66.
Testo completoAbstract (sommario):
A large number of weed seeds in the soil persist because of seed dormancy, and depletion of the seed bank through manipulation of seed dormancy has been suggested as one of the goals in weed control. This study was designed to investigate some of the factors which control dormancy and germination in Amaranthus retroflexus seeds. Germination studies were conducted at different temperatures, and either in continuous white light or in the dark. Higher temperatures increased germination and, although light interacted with temperature, its effect on germination varied with the temperature. In an attempt to determine changes in dormancy during dry storage, two lots of seeds were stored dry at different temperatures. Loss in dormancy increased with an increase in storage temperature and duration, but the time required for maximum germination varied according to the seedlot. Seeds germinated to higher percentages at high temperatures, but storage at higher temperatures and for prolonged duration resulted in seeds gaining the ability to germinate at lower temperatures. Changes in dormancy under field conditions were also examined. Seeds were buried at different depths and for different durations and they all lost viability with time, but this loss was greater in surface-sown and shallowly buried seeds. Dormancy was broken during cold periods and induced as warmer periods progressed. The effects of chemical stimulants on dormancy and germination were investigated. The response of seeds to ethephon and nitrate were assessed at different temperatures either at continuous white light or in the dark. Germination increased with the concentration of the chemicals, and a greater response was observed at lower temperatures. The response to light varied depending on temperatureMaster of Science (Hons)
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Omami, Elizabeth Nabwile. "Amaranthus retroflexus seed dormancy and germination responses to environmental factors and chemical stimulants". Thesis, [S.l. : s.n.], 1993. http://handle.uws.edu.au:8081/1959.7/66.
Testo completoAbstract (sommario):
A large number of weed seeds in the soil persist because of seed dormancy, and depletion of the seed bank through manipulation of seed dormancy has been suggested as one of the goals in weed control. This study was designed to investigate some of the factors which control dormancy and germination in Amaranthus retroflexus seeds. Germination studies were conducted at different temperatures, and either in continuous white light or in the dark. Higher temperatures increased germination and, although light interacted with temperature, its effect on germination varied with the temperature. In an attempt to determine changes in dormancy during dry storage, two lots of seeds were stored dry at different temperatures. Loss in dormancy increased with an increase in storage temperature and duration, but the time required for maximum germination varied according to the seedlot. Seeds germinated to higher percentages at high temperatures, but storage at higher temperatures and for prolonged duration resulted in seeds gaining the ability to germinate at lower temperatures. Changes in dormancy under field conditions were also examined. Seeds were buried at different depths and for different durations and they all lost viability with time, but this loss was greater in surface-sown and shallowly buried seeds. Dormancy was broken during cold periods and induced as warmer periods progressed. The effects of chemical stimulants on dormancy and germination were investigated. The response of seeds to ethephon and nitrate were assessed at different temperatures either at continuous white light or in the dark. Germination increased with the concentration of the chemicals, and a greater response was observed at lower temperatures. The response to light varied depending on temperature
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Dodds, Darrin Matthew. "Adjuvant effects on herbicide absorption and translocation". Diss., Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11022007-143506.
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Somireddy, Upender Reddy. "Effect of Herbicide-Organic Mulch Combinations on Weed Control and Herbicide Persistence". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1325255792.
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Filby, Amy Louisa. "Molecular effect pathways of endocrine disrupting chemicals in fish". Thesis, University of Exeter, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.439828.
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Umeda, Kai. "Effect of Halosulfuron on Rotational Crops". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2002. http://hdl.handle.net/10150/214957.
Testo completoAbstract (sommario):
A field test was conducted to evaluate and determine the safety of halosulfuron on typical rotational crops such as lettuce, broccoli, spinach, onion, alfalfa, barley, field corn, and melons after an initial application on cantaloupes. Halosulfuron at 0.05 or 0.1 lb AI/A applied on cantaloupes did not detrimentally affect crop stand establishment, height, or whole plant fresh weights when alfalfa, barley, spinach, lettuce, onion, and broccoli were planted at approximately 4 to 5 MAT. Cantaloupes and field corn planted at 1 YAT were not affected in establishing a stand and in growing during the early season as height or vine lengths were measured. At 15 to 16 MAT, lettuce, onion, and broccoli were not affected in establishing a stand. Watermelon planted at 1 YAT exhibited slight stand reduction and crop injury with halosulfuron applied PREE. Alfalfa planted after PREE applications indicated slightly depressed height and yield compared to POST treatments and the untreated check. Spinach planted where POST applications were made on cantaloupes tended to show a slight reduction in fresh weight at 15 to 16 MAT. Halosulfuron does not appear to be a major deterrent to typical crop rotational schemes in the diverse desert agricultural systems.
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Umeda, K., e N. Lund. "Effect of Prowl and Prefar Herbicides on Onions". College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2001. http://hdl.handle.net/10150/214935.
Testo completoAbstract (sommario):
Significant onion height reduction was observed when Prowl (pendimethalin) and Prefar (bensulide) herbicide combinations were applied preemergence (PREE). The onions resumed growth but the height was still slightly reduced later in the growing season compared to the handweeded check and the standard herbicide treatment, Dacthal (DCPA). The onion crop stand emerged initially but later in the season, a significant crop stand reduction was observed for the higher rate of Prowl at 0.5 lb AI/A plus Prefar. A lower rate of Prowl at 0.25 lb AI/A plus Prefar also caused a reduction of the onion stand compared to the handweeded check or Dacthal.
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Coberly, Samantha W. "The effect of household chemicals on deciduous and permanent tooth class". Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/6807.
Testo completoAbstract (sommario):
Dental anthropology was wide ranging implications for the field of anthropology. Teeth have become important sources of data about the individual as well as possibly being able to identify them. One problem that can arise is the chemical destruction of teeth whether it be diagenesis in an archaeological context or deliberately in a forensic context. In terms of deliberate destruction of the body several household chemicals are cheap and easily assessable. The purpose of this research is to look at how six household chemicals affect both deciduous and permanent tooth classes. The six chemicals include, Vinegar (acetic acid), Bleach (sodium hypochlorite), Biz (Sodium per carbonate), Lye (Sodium Hydroxide) Ammonia and the control (tap water). The teeth were placed in jars containing the chemical for twenty-four hours. Every hour the weight and mesial/distal length were measured. Of the six chemicals, vinegar affected the teeth the most.Thesis (M.A.)--Wichita State University, Fairmount College of Liberal Arts and Sciences, Dept. of Anthropology
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Turan, Nahid. "The effect of plasticisers and related chemicals on sulphate supply enzymes". Thesis, University of Birmingham, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.433746.
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Delacruz, C. Ligia. "The effect of natural toxicants and other chemicals on the kidney". Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/847359/.
Testo completoAbstract (sommario):
Repeated administration of ochratoxin A (OTA) caused renal morphological dose-related changes, that were associated with proximal tubular and glomerular damage the latter showing oedema and prominent PAS staining suggestive of glomerular basement membrane thickening. On the other hand, the combined administration of repeated doses of OTA and aflatoxin B[1] (2. 5 mg and 100 ug per kg, respectively), appeared to have a synergistic effect, characterized by severe disruption of proximal tubules and general morphological derrangement of the glomerulus, involving intense and faint staining nuclei (suggestive of cell necrosis) and cytoplasmic vacuolation, which was not seen with either toxin alone. When clinical biochemical parameters were measured after repeated administration of a low dose of OTA, enzymuria, glucosuria, polyuria and proteinuria were observed, with glucose and alkaline phosphatase as the most sensitive parameters. Metabolic studies performed in vitro showed that isolated pig and rat glomeruli incorporate different amino acids linearly for several hours at different rates and perform oxidative metabolism of glucose and fatty acids to CO[2] also linearly. For pig glomeruli the order of amino acid incorporation was LEU >> PRO = HIS > LYS > GLY and for rat glomeruli it was TRP >> PHE > TYR = LEU > PRO > HIS. The same amino acids were incorporated in a similar way in rat tubules, but the incorporation rate is 10-fold lower. When de novo synthesis of protein by pig glomeruli exposed to different chemicals was assessed, using proline (PRO) as the precursor, adriamycin (ADR) and ethacrynic acid (ETA) inhibited protein synthesis more than 2-bromoethanamine (BEA) and streptomycin (STR), and much more than puromycin aminonucleoside (PAN). When isolated rat glomeruli were exposed to low concentrations of OTA, there was a generalized inhibition on de novo synthesis of protein from the six amino acids tested and the aromatic amino acids (TRP, TYR and PHE) were more sensitive to OTA effect than PRO. Low concentrations of OTA (10 - 100 uM) enhanced glomerular and tubular glucose metabolism to CO[2] and only high concentrations of the mycotoxin (1000 uM) caused significant inhibition of glomerular and proximal tubular linolenic acid metabolism.
Libri sul tema "Effect of chemicals on weeds"
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Cantrell, Rick L. A guide to silvicultural herbicide use in the southern United States. Auburn, Ala: Auburn University, School of Forestry, Alabama Agricultural Experiment Station, 1985.
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Cantrell, Rick L. A guide to silvicultural herbicide use in the Southern United States: Special forms. Auburn University, Ala: Alabama Agricultural Experiment Station, 1985.
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Simard, S. Nine-year response of Engelmann spruce and the Willow Complex to chemical and manual release treatments on a ICHmw2 site near Vernon. Victoria, B.C: Canadian Forest Service, 1996.
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Simard, S. Nine-year response of Douglas-fir and the Mixed Hardwood-Shrub Complex to chemical and manual release treatments on an ICHmw2 site near Salmon Arm. Victoria, B.C: Canadian Forest Service, 1996.
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Weeding without chemicals. New York: Skyhorse Pub., 2012.
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Scott, R. C. Recommended chemicals for weed and brush control. Little Rock]: University of Arkansas Division of Agriculture, Cooperative Extension Services, 2006.
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Mallory-Smith, Carol. Herbicide-resistant weeds and their management. [Moscow, Idaho]: University of Idaho Cooperativae Extension System, 1993.
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Mallory-Smith, Carol. Herbicide-resistant weeds and their management. [Moscow, Idaho]: University of Idaho Cooperativae Extension System, 1993.
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Mallory-Smith, Carol. Herbicide-resistant weeds and their management. [Moscow, Idaho]: University of Idaho Cooperativae Extension System, 1993.
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Mallory-Smith, Carol. Herbicide-resistant weeds and their management. [Moscow, Idaho]: University of Idaho Cooperativae Extension System, 1999.
Cerca il testo completoCapitoli di libri sul tema "Effect of chemicals on weeds"
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Moore, Kenneth E., A. S. Heller e Arthur L. Lowe. "Chemical Composition of Nuclear Reactor Vessel Welds". In Effects of Radiation on Materials: 12th International Symposium Volume II, 1046–58. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 1985. http://dx.doi.org/10.1520/stp87019850030.
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Saha, Biswanath, Heena Kauser, Meena Khwairakpam e Ajay S. Kalamdhad. "Effect and Management of Various Terrestrial Weeds—Review". In Lecture Notes in Civil Engineering, 231–38. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-0990-2_17.
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Andrews, D. F., e A. M. Herzberg. "Effect of Chemicals on Earthworm Populations". In Springer Series in Statistics, 301–6. New York, NY: Springer New York, 1985. http://dx.doi.org/10.1007/978-1-4612-5098-2_53.
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Rana, Neha, Aruna V. Varanasi e Brent A. Sellers. "Effect of Environmental Factors on Weed Germination and Management". In Biology, Physiology and Molecular Biology of Weeds, 27–44. Boca Raton, FL: CRC Press, 2017. | “A science publishers book.”: CRC Press, 2017. http://dx.doi.org/10.1201/9781315121031-3.
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Weekers, F., Ph Thonart, Ph Jacques, D. Springael, M. Mergeay e L. Diels. "Effect of Drying on Bioremediation Bacteria Properties". In Biotechnology for Fuels and Chemicals, 311–22. Totowa, NJ: Humana Press, 1998. http://dx.doi.org/10.1007/978-1-4612-1814-2_30.
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Phalen, R. N. "Testing of Protective Effect against Liquid Chemicals". In Protective Gloves for Occupational Use, 121–40. 3a ed. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003126874-12.
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Du, Liping, Aleš Prokop e Robert D. Tanner. "Effect of Bubble Size on Foam Fractionation of Ovalbumin". In Biotechnology for Fuels and Chemicals, 1075–91. Totowa, NJ: Humana Press, 2002. http://dx.doi.org/10.1007/978-1-4612-0119-9_87.
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Burapatana, Vorakan, Ernest E. Butler, Gaurav Chauhan, Sean Hartig, Helen Kincaid, Tong Wang, Shayrizal Samsudin e Robert D. Tanner. "Effect of Lidocaine on Ovalbumin and Egg Albumin Foam Stability". In Biotechnology for Fuels and Chemicals, 905–11. Totowa, NJ: Humana Press, 2003. http://dx.doi.org/10.1007/978-1-4612-0057-4_76.
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Bredwell, M. D., M. D. Telgenhoff, S. Barnard e R. M. Worden. "Effect of Surfactants on Carbon Monoxide Fermentations by Butyribacterium methylotrophicum". In Biotechnology for Fuels and Chemicals, 637–47. Totowa, NJ: Humana Press, 1997. http://dx.doi.org/10.1007/978-1-4612-2312-2_56.
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Gottschalk, Leda M. F., Ronaldo Nobrega e Elba P. S. Bon. "Effect of Aeration on Lignin Peroxidase Production by Streptomyces viridosporus T7A". In Biotechnology for Fuels and Chemicals, 799–807. Totowa, NJ: Humana Press, 2003. http://dx.doi.org/10.1007/978-1-4612-0057-4_67.
Testo completoAtti di convegni sul tema "Effect of chemicals on weeds"
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Reátegui, Eduardo, Erik Reynolds, Lisa Kasinkas, Amit Aggarwal, Michael J. Sadowsky, Alptekin Aksan e Lawrence P. Wackett. "Reactive Biomaterial for the Treatment of Herbicide Contaminated Drinking Water: Atrazine Dechlorination". In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80205.
Testo completoAbstract (sommario):
The herbicide atrazine is used for control of broadleaf weeds, principally in corn, sorghum, and sugarcane [1]. Atrazine is currently used in 70 countries at an estimated annual rate of 111,000 tons [2, 3]. Atrazine is typically applied early in the planting season. However, Heavy rainfall events, shortly after application may lead to detectable atrazine concentrations in waterways and in drinking-water supplies. The United States Environmental Protection Agency established a 3 ppb limit of atrazine in drinking water. In some instances, municipal water treatment plants use chemicals and other treatment processes, such as activated carbon, to reduce atrazine to below the 3 ppb legal limit for drinking water.
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SPRUOGIS, Vidmantas, Anželika DAUTARTĖ, Romualdas ZEMECKIS, Edmundas BARTKEVIČIUS e Aida STIKLIENĖ. "THE INFLUENCE OF BIOORGANIC PREPARATIONS ON THE PRODUCTIVITY OF CONVENTIONALY GROWN WINTER WHEAT ACTIVATING AND SAVING THE USE OF SYNTHETIC CHEMICALS". In RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.080.
Testo completoAbstract (sommario):
The influence of Raskila bioorganic fertilisers on the productivity of conventional winter wheat ‘Olivin’, was investigated in order to stimulate and save synthetic herbicide Arrat and fungicide Tango Super for spring spraying. Scheme of treatment: 1. Control; 2. Winter wheat sprayed (BBCH 20-29) with fertilizer Raskila 3 l ha-1; 3. Winter wheat sprayed (BBCH 20-29) with Arrat 0.2 kg ha-1+Tango super 1.5 l ha-1; 4. Winter wheat sprayed (BBCH 20-29) with Arrat 0.2 kg ha-1+Tango super 1.5 l ha-1+Raskila 3.0 l ha-1; 5. Winter wheat sprayed (BBCH 20-29) with Arrat 0.1 kg ha-1+Tango super 0.75 l ha-1+Raskila 3.0 l ha-1. The best result in the period of 2014-2016 was received after application of the following combination in spring: Arrat + Tango super + Raskila. This combination allows to reduce the rate of pesticides in half (50%), the differences compared to control are significant, statistically reliable. A statistically significant increase in the following winter wheat ‘Olivin’ quality parameters was found: protein 13.1-14.8%, gluten 24.3-29.7%, number of falls 228-292 s, starch 65.7-70.0%. Application of Raskila fertilizers has raised the grain quality class. The best results were in variants 3 and 4, where the I class of grain quality was achieved. Combination of Raskila fertilisers and pesticides: herbicide Arrat and fungicide Tango super statistically significantly increased the following winter wheat ‘Olivin’ characteristics - plant height 101.2-104.2 cm, ear length 6.9-7.1 cm, grain number per ear 28,96- 30.02, grain yield 6.71-7.03 t ha-1. Application of Raskila fertilizer 1.0 l ha-1 and herbicide Arrat 0.1 kg ha-1 decreased the number of weeds from 62.5 to 57.6 units per m2 and the weed weight decreased from 41.30 to 33.70 g m2. Stronger wheat crop overshadowed weeds better. Combination of Raskila and Tango super reduced the prevalence and severity of diseases in winter wheat such as Septoria spp., Pyrenophora tritici-repentis, Erysiphe graminis, powdery rust (Puccinia recondita).
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ČESONIENĖ, Laima, Kristina LINGYTĖ, Daiva ŠILEIKIENĖ e Midona DAPKIENĖ. "GROUNDWATER QUALITY DYNAMICS IN THE TERRITORY OF FORMER PESTICIDE WAREHOUSE". In RURAL DEVELOPMENT. Aleksandras Stulginskis University, 2018. http://dx.doi.org/10.15544/rd.2017.097.
Testo completoAbstract (sommario):
Pesticides are used in intensive farming to help fight plant pests and diseases (insecticides, fungicides), kill weeds (herbicides), as well as accelerate the growth of seeds (defoliants), but until 1992 pesticides were kept in improperly equipped warehouses, there was no maintenance or accounting of the pesticides. Consequently, the environment of the warehouse was often polluted. Such sources of pollution are hazardous to the environment. Economic activities in the area have been carried out from 1980 to 1994. Various agricultural chemicals have been stored and used there. Later, in 1997, chemicals (fertilizers and plant protection chemicals) stored in the territory of the warehouse have been collected and removed from the territory. During the inventory of 2009, no chemical substances were found in the territory. In 2010, an investigation carried out in the territory of the pesticide warehouse revealed unacceptable levels of pollution in the soil and the groundwater by pesticides and other toxic and neutral chemicals. In 2012, the polluted territory was cleaned eliminating the remains of buildings, and removing the soil polluted by the pesticides. The aim of the study was to evaluate the impact of the territory of the former pesticide warehouse in Kaunas District Municipality, Bubių Village on the groundwater during the period from 2012 to 2016. The results have shown that the groundwater is mostly polluted with nitrogen compounds, as well as the tendency in increase of chlorides, sodium, and calcium. Minimum and unchanging concentrations of the pesticides (DDD, DDE, DDT) were determined throughout the investigation.
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Shi, Lei, Hua Liu, Yumei Wei, Ming Ma e Rui Jiang. "The Persistence of Invasion and Diffusion Model of Poisonous Weeds with Allee Effect". In 2017 International Conference on Applied Mathematics, Modeling and Simulation (AMMS 2017). Paris, France: Atlantis Press, 2017. http://dx.doi.org/10.2991/amms-17.2017.36.
Testo completo
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Choi, Kyoung Joon, Seung Chang Yoo, Chi Bum Bahn e Ji Hyun Kim. "Investigation of Microstructural Changes due to Thermal Aging in Dissimilar Metal Welds". In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28699.
Testo completoAbstract (sommario):
To investigate the effect of long-term thermal aging on the fusion boundary region between low-alloy steel A533 Gr. B and weld metal Alloy 152, a representative dissimilar weld mockup composed of Alloy 690/Alloy 152/A533 Gr. B was aged in laboratory furnaces under accelerated temperature conditions. The aging time was determined using the diffusion equation. The heat treatment was performed at 450°C for 60-y equivalent time (5,500 h) to simulate thermal aging effects. An additional aging heat treatment was also performed at 400°C for 15- and 30-y equivalent times (6,450 and 12,911 h, respectively) to determine the effects of temperature on aged microstructures. The characterization was mainly conducted in the microstructure of the fusion boundary region in the weld root region using scanning electron microscopy, transmission electron microscopy, and three-dimensional atom probe tomography. It was determined that the region near the fusion boundary was generally divided into several regions, such as a dilution zone (that included a chemical gradient in the weld side), fusion boundary, and heat-affected zone in the low-alloy steel. The results of this study showed that heat treatment increased Cr content in the dilution zone, but the chemical gradient in the weld side near the fusion boundary persisted. For the microstructure, it was observed that treatment induced the formation and growth of Cr precipitates in the fusion boundary region of the dissimilar metal joints due to the thermodynamic driving force. At two heat treatment conditions (400 and 450°C), although the extent of the results described above differed, the trend in the results appeared to be the same. This microstructure information can improve the understanding of cracking-resistant change when structural changes occur. Furthermore, such data will be important for assessing the effects of aging on structural components and for evaluating the long-term operation of nuclear power plants.
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Yuce, H. H., A. D. Hasse e P. L. Key. "Effect Of Common Chemicals On The Mechanical Properties Of Optical Fibers". In O-E/Fiber LASE '88, a cura di Roger A. Greenwell, Dilip K. Paul e Shekhar G. Wadekar. SPIE, 1989. http://dx.doi.org/10.1117/12.960047.
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Arbab, M. Hassan, Antao Chen, Eric I. Thorsos, Dale P. Winebrenner e Lisa M. Zurk. "Effect of surface scattering on terahertz time domain spectroscopy of chemicals". In Integrated Optoelectronic Devices 2008, a cura di Kurt J. Linden e Laurence P. Sadwick. SPIE, 2008. http://dx.doi.org/10.1117/12.769015.
Testo completo
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Krustev, Angel, Boian Alexandrov e Jerry Kovacich. "Modified GTAW Orbital Tube-to-Tubesheet Welding Technique, and the Effect of a Copper Weld Retainer During Welding of Alloy 825". In ASME 2017 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/pvp2017-65971.
Testo completoAbstract (sommario):
Tube-to-tubesheet welds are an essential part of the design of heat exchangers used in power generation, petro-chemical, chemical processing, pharmaceutical, and food processing industries. The tube-to-tubesheet welds are typically produced using gas tungsten arc welding (GTAW) with or without the addition of filler wire, and involve carbon steels and various creep and corrosion resistant alloys. The weld heat input in tube-to-tubesheet welds is an essential parameter that controls the productivity and weld quality, in terms of weld bead geometry and heat affected zone microstructure and properties. A modified GTAW tube-to-tubesheet orbital welding head that utilizes a copper weld retainer is described in this paper. The copper weld retainer provides a heat sink during welding, and supports the molten weld metal. This permits the use of a relatively high heat input, required for a single pass welding with filler wire addition. Furthermore, the copper retainer limits the amount of weld overlap into the tube bore. The application of the modified orbital welding technique, which helped for resolving a suspected liquation cracking problem in Alloy 825 tube to 316L stainless steel tubesheet welds, is presented.
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Nalasavagan, Kausalyah, Harun bin Abdul Rahman, Mohd Fairuz bin Azman e Rizal bin Bakar. "Managing Accelerated Water Breakthrough in High Permeability Contrast Waterflood Reservoirs, and Achieving Production Conformance Through Injection Redistribution Strategy". In ADIPEC. SPE, 2022. http://dx.doi.org/10.2118/211195-ms.
Testo completoAbstract (sommario):
Abstract Waterflooding for pressure maintenance often seems straightforward with key objective being voidage replacement as demonstrated through material balance. Even though pressure maintenance can be achieved, it may not directly translate into higher production if efficient sweep is not attained, and oil has been bypassed. This paper demonstrates a real case study at Field S on how swift and integrated mitigation plan successfully addressed the production impairment during the initial water injection period. Field S started injection through newly drilled peripheral water injectors to fill up the voidage created by earlier production volumes hence tempered the pressure decline. Reservoir response was observed from downhole pressure gauges as early as after the first few days of injection in several producers. The first water breakthrough was then identified few months after at the most up-dip wells and resulted in producers died off. At the expense of voidage replacement ratio (VRR) performance, intermittent flow strategy was deployed as temporary measure, to revive and keep the producers flowing, while flow diverter chemicals have been under evaluation to serve as a more sustainable solution. Impacted producers were determined to have good connectivity with the injectors as shown by streamline analysis, diagnostic plot, salinity measurement and log correlation. This is easily validated with pressure response recorded via PDG (pressure downhole gauge) throughout injection period. It was observed that high permeability contrast ratio presence across multiple sand lobes at the affected producers with the highest permeability was recorded up to Darcy range. While such contrast was absent at injectors, this specific sand lobe still effectively provides the preferential flow path between injectors to producers and lead to channeling effect. Managing drawdown through choke optimization was ineffective as the short distance between injectors and producers allows rapid water charging through the high permeability streak. However, shutting-in injection temporarily managed to slow down water production almost promptly. Subsequently, intermittent injection strategy implementation enabled certain amount of solution gas being liberated to provide in-situ gas lift effect inside the tubing for continuous production. The producers were successfully put back on production within weeks with close monitoring and surveillance. Next step, flow diverter chemical will be injected to partially block the channeling path, hence maximizing the well potential and oil recovery. Production upset caused by early water breakthrough is a common issue in waterflood reservoir. However, by understanding the root cause, supported by prudent surveillance practices and operation flexibility, the production downtime can be minimized as showcased in this paper. Besides, geological and petrophysical input are pivotal in understanding reservoir or well performance issues.
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Manu, J., e Vasudeva Madav. "Hydrodynamic effect of elastic and inelastic collisions in fluidized bubbling bed reactor". In NATIONAL CONFERENCE ON ENERGY AND CHEMICALS FROM BIOMASS (NCECB). AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0005565.
Testo completoRapporti di organizzazioni sul tema "Effect of chemicals on weeds"
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Miles, Gaines E., Yael Edan, F. Tom Turpin, Avshalom Grinstein, Thomas N. Jordan, Amots Hetzroni, Stephen C. Weller, Marvin M. Schreiber e Okan K. Ersoy. Expert Sensor for Site Specification Application of Agricultural Chemicals. United States Department of Agriculture, agosto 1995. http://dx.doi.org/10.32747/1995.7570567.bard.
Testo completoAbstract (sommario):
In this work multispectral reflectance images are used in conjunction with a neural network classifier for the purpose of detecting and classifying weeds under real field conditions. Multispectral reflectance images which contained different combinations of weeds and crops were taken under actual field conditions. This multispectral reflectance information was used to develop algorithms that could segment the plants from the background as well as classify them into weeds or crops. In order to segment the plants from the background the multispectrial reflectance of plants and background were studied and a relationship was derived. It was found that using a ratio of two wavelenght reflectance images (750nm and 670nm) it was possible to segment the plants from the background. Once ths was accomplished it was then possible to classify the segmented images into weed or crop by use of the neural network. The neural network developed for this work is a modification of the standard learning vector quantization algorithm. This neural network was modified by replacing the time-varying adaptation gain with a constant adaptation gain and a binary reinforcement function. This improved accuracy and training time as well as introducing several new properties such as hill climbing and momentum addition. The network was trained and tested with different wavelength combinations in order to find the best results. Finally, the results of the classifier were evaluated using a pixel based method and a block based method. In the pixel based method every single pixel is evaluated to test whether it was classified correctly or not and the best weed classification results were 81% and its associated crop classification accuracy is 57%. In the block based classification method, the image was divided into blocks and each block was evaluated to determine whether they contained weeds or not. Different block sizes and thesholds were tested. The best results for this method were 97% for a block size of 8 inches and a pixel threshold of 60. A simulation model was developed to 1) quantify the effectiveness of a site-specific sprayer, 2) evaluate influence of diffeent design parameters on efficiency of the site-specific sprayer. In each iteration of this model, infected areas (weed patches) in the field were randomly generated and the amount of required herbicides for spraying these areas were calculated. The effectiveness of the sprayer was estimated for different stain sizes, nozzle types (conic and flat), nozzle sizes and stain detection levels of the identification system. Simulation results indicated that the flat nozzle is much more effective as compared to the conic nozzle and its relative efficiency is greater for small nozzle sizes. By using a site-specific sprayer, the average ratio between the spraying areas and the stain areas is about 1.1 to 1.8 which can save up to 92% of herbicides, especially when the proportion of the stain areas is small.
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Lorenz, P. B. The effect of alkaline agents on retention of EOR chemicals. Office of Scientific and Technical Information (OSTI), luglio 1991. http://dx.doi.org/10.2172/5629326.
Testo completo
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Petit, Sylvain, Joannie Chin, Amanda Forster, Michael Riley e Kirk Rice. Effect of artificial perspiration and cleaning chemicals on mechanical and chemical properties of ballistic fibers. Gaithersburg, MD: National Institute of Standards and Technology, 2008. http://dx.doi.org/10.6028/nist.ir.7494.
Testo completo
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VanderGheynst, Jean, Michael Raviv, Jim Stapleton e Dror Minz. Effect of Combined Solarization and in Solum Compost Decomposition on Soil Health. United States Department of Agriculture, ottobre 2013. http://dx.doi.org/10.32747/2013.7594388.bard.
Testo completoAbstract (sommario):
In soil solarization, moist soil is covered with a transparent plastic film, resulting in passive solar heating which inactivates soil-borne pathogen/weed propagules. Although solarization is an effective alternative to soil fumigation and chemical pesticide application, it is not widely used due to its long duration, which coincides with the growing season of some crops, thereby causing a loss of income. The basis of this project was that solarization of amended soil would be utilized more widely if growers could adopt the practice without losing production. In this research we examined three factors expected to contribute to greater utilization of solarization: 1) investigation of techniques that increase soil temperature, thereby reducing the time required for solarization; 2) development and validation of predictive soil heating models to enable informed decisions regarding soil and solarization management that accommodate the crop production cycle, and 3) elucidation of the contributions of microbial activity and microbial community structure to soil heating during solarization. Laboratory studies and a field trial were performed to determine heat generation in soil amended with compost during solarization. Respiration was measured in amended soil samples prior to and following solarization as a function of soil depth. Additionally, phytotoxicity was estimated through measurement of germination and early growth of lettuce seedlings in greenhouse assays, and samples were subjected to 16S ribosomal RNA gene sequencing to characterize microbial communities. Amendment of soil with 10% (g/g) compost containing 16.9 mg CO2/g dry weight organic carbon resulted in soil temperatures that were 2oC to 4oC higher than soil alone. Approximately 85% of total organic carbon within the amended soil was exhausted during 22 days of solarization. There was no significant difference in residual respiration with soil depth down to 17.4 cm. Although freshly amended soil proved highly inhibitory to lettuce seed germination and seedling growth, phytotoxicity was not detected in solarized amended soil after 22 days of field solarization. The sequencing data obtained from field samples revealed similar microbial species richness and evenness in both solarized amended and non-amended soil. However, amendment led to enrichment of a community different from that of non-amended soil after solarization. Moreover, community structure varied by soil depth in solarized soil. Coupled with temperature data from soil during solarization, community data highlighted how thermal gradients in soil influence community structure and indicated microorganisms that may contribute to increased soil heating during solarization. Reliable predictive tools are necessary to characterize the solarization process and to minimize the opportunity cost incurred by farmers due to growing season abbreviation, however, current models do not accurately predict temperatures for soils with internal heat generation associated with the microbial breakdown of the soil amendment. To address the need for a more robust model, a first-order source term was developed to model the internal heat source during amended soil solarization. This source term was then incorporated into an existing “soil only” model and validated against data collected from amended soil field trials. The expanded model outperformed both the existing stable-soil model and a constant source term model, predicting daily peak temperatures to within 0.1°C during the critical first week of solarization. Overall the results suggest that amendment of soil with compost prior to solarization may be of value in agricultural soil disinfestations operations, however additional work is needed to determine the effects of soil type and organic matter source on efficacy. Furthermore, models can be developed to predict soil temperature during solarization, however, additional work is needed to couple heat transfer models with pathogen and weed inactivation models to better estimate solarization duration necessary for disinfestation.
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Sessa, Guido, e Gregory Martin. A functional genomics approach to dissect resistance of tomato to bacterial spot disease. United States Department of Agriculture, gennaio 2004. http://dx.doi.org/10.32747/2004.7695876.bard.
Testo completoAbstract (sommario):
The research problem. Bacterial spot disease in tomato is of great economic importance worldwide and it is particularly severe in warm and moist areas affecting yield and quality of tomato fruits. Causal agent of spot disease is the Gram-negative bacterium Xanthomonas campestris pv. vesicatoria (Xcv), which can be a contaminant on tomato seeds, or survive in plant debris and in association with certain weeds. Despite the economic significance of spot disease, plant protection against Xcvby cultural practices and chemical control have so far proven unsuccessful. In addition, breeding for resistance to bacterial spot in tomato has been undermined by the genetic complexity of the available sources of resistance and by the multiple races of the pathogen. Genetic resistance to specific Xcvraces have been identified in tomato lines that develop a hypersensitive response and additional defense responses upon bacterial challenge. Central goals of this research were: 1. To identify plant genes involved in signaling and defense responses that result in the onset of resistance. 2. To characterize molecular properties and mode of action of bacterial proteins, which function as avirulence or virulence factors during the interaction between Xcvand resistant or susceptible tomato plants, respectively. Our main achievements during this research program are in three major areas: 1. Identification of differentially expressed genes during the resistance response of tomato to Xcvrace T3. A combination of suppression subtractive hybridization and microarray analysis identified a large set of tomato genes that are induced or repressed during the response of resistant plants to avirulent XcvT3 bacteria. These genes were grouped in clusters based on coordinate expression kinetics, and classified into over 20 functional classes. Among them we identified genes that are directly modulated by expression of the type III effector protein AvrXv3 and genes that are induced also during the tomato resistance response to Pseudomonas syringae pv. tomato. 2. Characterization of molecular and biochemical properties of the tomato LeMPK3MAP kinase. A detailed molecular and biochemical analysis was performed for LeMPK3 MAP kinase, which was among the genes induced by XcvT3 in resistant tomato plants. LeMPK3 was induced at the mRNA level by different pathogens, elicitors, and wounding, but not by defense-related plant hormones. Moreover, an induction of LeMPK3 kinase activity was observed in resistant tomato plants upon Xcvinfection. LeMPK3 was biochemically defined as a dual-specificity MAP kinase, and extensively characterized in vitro in terms of kinase activity, sites and mechanism of autophosphorylation, divalent cation preference, Kₘand Vₘₐₓ values for ATP. 3. Characteriztion of molecular properties of the Xcveffector protein AvrRxv. The avirulence gene avrRxvis involved in the genetic interaction that determines tomato resistance to Xcvrace T1. We found that AvrRxv functions inside the plant cell, localizes to the cytoplasm, and is sufficient to confer avirulence to virulent Xcvstrains. In addition, we showed that the AvrRxv cysteine protease catalytic core is essential for host recognition. Finally, insights into cellular processes activated by AvrRxv expression in resistant plants were obtained by microarray analysis of 8,600 tomato genes. Scientific and agricultural significance: The findings of these activities depict a comprehensive and detailed picture of cellular processes taking place during the onset of tomato resistance to Xcv. In this research, a large pool of genes, which may be involved in the control and execution of plant defense responses, was identified and the stage is set for the dissection of signaling pathways specifically triggered by Xcv.
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Belkin, Shimshon, Sylvia Daunert e Mona Wells. Whole-Cell Biosensor Panel for Agricultural Endocrine Disruptors. United States Department of Agriculture, dicembre 2010. http://dx.doi.org/10.32747/2010.7696542.bard.
Testo completoAbstract (sommario):
Objectives: The overall objective as defined in the approved proposal was the development of a whole-cell sensor panel for the detection of endocrine disruption activities of agriculturally relevant chemicals. To achieve this goal several specific objectives were outlined: (a) The development of new genetically engineered wholecell sensor strains; (b) the combination of multiple strains into a single sensor panel to effect multiple response modes; (c) development of a computerized algorithm to analyze the panel responses; (d) laboratory testing and calibration; (e) field testing. In the course of the project, mostly due to the change in the US partner, three modifications were introduced to the original objectives: (a) the scope of the project was expanded to include pharmaceuticals (with a focus on antibiotics) in addition to endocrine disrupting chemicals, (b) the computerized algorithm was not fully developed and (c) the field test was not carried out. Background: Chemical agents, such as pesticides applied at inappropriate levels, may compromise water quality or contaminate soils and hence threaten human populations. In recent years, two classes of compounds have been increasingly implicated as emerging risks in agriculturally-related pollution: endocrine disrupting compounds (EDCs) and pharmaceuticals. The latter group may reach the environment by the use of wastewater effluents, whereas many pesticides have been implicated as EDCs. Both groups pose a threat in proportion to their bioavailability, since that which is biounavailable or can be rendered so is a priori not a threat; bioavailability, in turn, is mediated by complex matrices such as soils. Genetically engineered biosensor bacteria hold great promise for sensing bioavailability because the sensor is a live soil- and water-compatible organism with biological response dynamics, and because its response can be genetically “tailored” to report on general toxicity, on bioavailability, and on the presence of specific classes of toxicants. In the present project we have developed a bacterial-based sensor panel incorporating multiple strains of genetically engineered biosensors for the purpose of detecting different types of biological effects. The overall objective as defined in the approved proposal was the development of a whole-cell sensor panel for the detection of endocrine disruption activities of agriculturally relevant chemicals. To achieve this goal several specific objectives were outlined: (a) The development of new genetically engineered wholecell sensor strains; (b) the combination of multiple strains into a single sensor panel to effect multiple response modes; (c) development of a computerized algorithm to analyze the panel responses; (d) laboratory testing and calibration; (e) field testing. In the course of the project, mostly due to the change in the US partner, three modifications were introduced to the original objectives: (a) the scope of the project was expanded to include pharmaceuticals (with a focus on antibiotics) in addition to endocrine disrupting chemicals, (b) the computerized algorithm was not fully developed and (c) the field test was not carried out. Major achievements: (a) construction of innovative bacterial sensor strains for accurate and sensitive detection of agriculturally-relevant pollutants, with a focus on endocrine disrupting compounds (UK and HUJ) and antibiotics (HUJ); (b) optimization of methods for long-term preservation of the reporter bacteria, either by direct deposition on solid surfaces (HUJ) or by the construction of spore-forming Bacillus-based sensors (UK); (c) partial development of a computerized algorithm for the analysis of sensor panel responses. Implications: The sensor panel developed in the course of the project was shown to be applicable for the detection of a broad range of antibiotics and EDCs. Following a suitable development phase, the panel will be ready for testing in an agricultural environment, as an innovative tool for assessing the environmental impacts of EDCs and pharmaceuticals. Furthermore, while the current study relates directly to issues of water quality and soil health, its implications are much broader, with potential uses is risk-based assessment related to the clinical, pharmaceutical, and chemical industries as well as to homeland security.
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Chejanovsky, Nor, e Bruce D. Hammock. Enhancement of Baculoviruses' Insecticidal Potency by Expression of Synergistic Anti-Insect Scorpion Toxins. United States Department of Agriculture, gennaio 1996. http://dx.doi.org/10.32747/1996.7573070.bard.
Testo completoAbstract (sommario):
The extensive use or non-specific, hazardous, chemical insecticides demands the development of "healthier" alternative means for pest control. Insect-specific, baculoviruses expressing anti-insect toxin genes (from mites or scorpions) demonstrated in laboratory assays and field trials enhanced insecticidal activity and provided some protection from lepidopterous larvae to agricultural plantations. To utilize recombinant baculoviruses as commercial biopesticides in row crop agriculture, further increase in their speed of kill should be achieved and the reduction in crop damage should be comparable to the levels obtained with organic insecticides (the problem). In this project we developed strategies to improve further the efficacy of recombinant baculoviruses which included: I) Synergism among baculoviruses expressing different anti-insect toxins: a) Synergism among two complementary anti-insect scorpion neurotoxins each expressed by a separate recombinant baculovirus, both regulated by the same or a different viral promoter. b) Synergism among two complementary anti-insect scorpion neurotoxins expressed by the same recombinant virus, both regulated by the same or a different viral promoter respectively. The above included two classes of pharmacologically complementary toxins: i) toxins with strictly anti-insect selectivity (excitatory and depressant); ii) toxins with preferential anti-insect activity (anti-insect alpha toxins). c) Synergism among wild type viruses, recombinant baculoviruses and chemicals (insecticides and phytochemicals) II) Identification of more potent toxins against lepidopterous pests for their expression by baculoviruses. Our approach was based on the synergistic effect displayed by the combined application of pairs of anti-insect toxins to blowfly and lepidopterous larvae that resulted in 5 fold increase in their insecticidal activity without apparent increase in their anti-mammal toxicity (toxins LqhIT2 and LqhaIT, LqhIT2 and AaIT, and LqhaIT and AaIT (1). Thus, we developed new concepts and produced a "second generation" of recombinant baculoviruses with enhanced potencies and speeds of kill comparable to classical insecticides. These achievements contribute to make these biopesticides a viable alternative to minimize the use of hazardous chemicals in pest control. Also, our project contributed new tools and model systems to advance the study of insect sodium channels.
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Friedlander, Michael, Clinton Dawes e Y. (Joel) Kashman. The Interaction between Epiphytes and Seaweeds. United States Department of Agriculture, giugno 1995. http://dx.doi.org/10.32747/1995.7571355.bard.
Testo completoAbstract (sommario):
Two Israeli laboratories (IOLR and TAU) cooperated with one American laboratory (USF) in the research of the interaction between epiphytes (Ulva sp.) and the cultivated seaweed (Gracilaria sp.) The main objectives included the following aspects: Structural aspects, effects of different irradiances on growth, sensitivity studies, allelopathic excretions, selective chemicals and integration of studies of epiphytization. The studies were operated in outdoor tanks, indoor growth chambers and in the lab. The main conclusions and their relevance for mariculture are as following: 1. The green algal epiphyte, does penetrate its red algal host. 2. Gracilaria spp. in monoculture released more halogenated hydrocarbons than in biculture with U lactuca, whereas other metabolic parameters did not show a discriminating effect in biculture. 3. Hydrogen peroxide and halogenated hydrocarbons could be a part of the effective excretion compounds in biculture. 4. The presence of mature Gracilaria inhibited the growth of U. lactuca sporelings. 5. G. conferta is most sensitive to epiphytes among Gracilaria species tested. 6. The use of green light can enhance growth in basiphytes but inhibit epiphytes. 7. Effective selectivity has been defined by the use of hydrogen hypochlorite. 8. It may be more profitable in seaweed mariculture to select for epiphyte resistant strains than to search for inhibitors of epiphytization. 9 It is important as well to examine how the basiphyte may be able to prevent penetration. 10. Definition of the effective excretions in biculture has still to be done.
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Chamovitz, A. Daniel, e Georg Jander. Genetic and biochemical analysis of glucosinolate breakdown: The effects of indole-3-carbinol on plant physiology and development. United States Department of Agriculture, gennaio 2012. http://dx.doi.org/10.32747/2012.7597917.bard.
Testo completoAbstract (sommario):
Genetic and biochemical analysis of glucosinolate breakdown: The effects of indole-3-carbinol on plant physiology and development Glucosinolates are a class of defense-related secondary metabolites found in all crucifers, including important oilseed and vegetable crops in the Brassica genus and the well-studied model plant Arabidopsis thaliana. Upon tissue damage, such as that provided by insect feeding, glucosinolates are subjected to catalysis and spontaneous degradation to form a variety of breakdown products. These breakdown products typically have a deterrent effect on generalist herbivores. Glucosinolate breakdown products also contribute to the anti-carcinogenic effects of eating cabbage, broccoli and related cruciferous vegetables. Indole-3-carbinol, a breakdown product of indol-3-ylmethylglucosinolate, forms conjugates with several other plant metabolites. Although some indole-3-carbinol conjugates have known functions in defense against herbivores and pathogens, most play as yet unidentified roles in plant metabolism, and possibly also plant development. At the outset, our proposal had three main hypotheses: (1) There is a specific detoxification pathway for indole-3-carbinol; (2) Metabolites derived from indole-3-carbinol are phloem-mobile and serve as signaling molecules; and (3) Indole-3-carbinol affects plant cell cycle and cell-differentiation pathways. The experiments were designed to enable us to elucidate how indole-3-carbinol and related metabolites affect plants and their interactions with herbivorous insects. We discovered that indole-3- carbinol rapidly and reversibly inhibits root elongation in a dose-dependent manner, and that this inhibition is accompanied by a loss of auxin activity in the root meristem. A direct interaction between indole-3-carbinol and the auxin perception machinery was suggested, as application of indole-3-carbinol rescued auxin-induced root phenotypes. In vitro and yeast-based protein interaction studies showed that indole-3-carbinol perturbs the auxin-dependent interaction of TIR1 with Aux/IAA proteins, supporting the notion that indole-3-carbinol acts as an auxin antagonist. Furthermore, transcript profiling experiments revealed the influence of indole-3-carbinol on auxin signaling in root tips, and indole-3-carbinol also affected auxin transporters. Brief treatment with indole-3-carbinol led to a reduction in the amount of PIN1 and to mislocalization of PIN2. The results indicate that chemicals induced by herbivory, such as indole-3-carbinol, function not only to repel herbivores, but also as signaling molecules that directly compete with auxin to fine tune plant growth and development, which implies transport of indole-3- carbinol that we are as yet unsuccessful in detecting. Our results indicate that plant defensive metabolites also have secondary functions in regulating aspects of plant metabolism, thereby providing diversity in defense-related plant signaling pathways. Such diversity of of signaling by defensive metabolites would be beneficial for the plant, as herbivores and pathogens would be less likely to mount effective countermeasures. We propose that growth arrest can be mediated directly by the herbivory-induced chemicals, in our case, indole-3-carbinol. Thus, glucosinolate breakdown to I3C following herbivory would have two outcomes: (1) Indole-3-carbinaol would inhibit the herbivore, while (2) at the same time inducing growth arrest within the plant. Thus, our results indicate that I3C is a defensive phytohormone that modulates auxin signaling, leading to growth arrest.
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Lahav, Ori, Albert Heber e David Broday. Elimination of emissions of ammonia and hydrogen sulfide from confined animal and feeding operations (CAFO) using an adsorption/liquid-redox process with biological regeneration. United States Department of Agriculture, marzo 2008. http://dx.doi.org/10.32747/2008.7695589.bard.
Testo completoAbstract (sommario):
The project was originally aimed at investigating and developing new efficient methods for cost effective removal of ammonia (NH₃) and hydrogen sulfide (H₂S) from Concentrated Animal Feeding Operations (CAFO), in particular broiler and laying houses (NH₃) and hog houses (H₂S). In both cases, the principal idea was to design and operate a dedicated air collection system that would be used for the treatment of the gases, and that would work independently from the general ventilation system. The advantages envisaged: (1) if collected at a point close to the source of generation, pollutants would arrive at the treatment system at higher concentrations; (2) the air in the vicinity of the animals would be cleaner, a fact that would promote animal growth rates; and (3) collection efficiency would be improved and adverse environmental impact reduced. For practical reasons, the project was divided in two: one effort concentrated on NH₃₍g₎ removal from chicken houses and another on H₂S₍g₎ removal from hog houses. NH₃₍g₎ removal: a novel approach was developed to reduce ammonia emissions from CAFOs in general, and poultry houses in particular. Air sucked by the dedicated air capturing system from close to the litter was shown to have NH₃₍g₎ concentrations an order of magnitude higher than at the vents of the ventilation system. The NH₃₍g₎ rich waste air was conveyed to an acidic (0<pH<~5) bubble column reactor where NH₃ was converted to NH₄⁺. The reactor operated in batch mode, starting at pH 0 and was switched to a new acidic absorption solution just before NH₃₍g₎ breakthrough occurred, at pH ~5. Experiments with a wide range of NH₃₍g₎ concentrations showed that the absorption efficiency was practically 100% throughout the process as long as the face velocity was below 4 cm/s. The potential advantages of the method include high absorption efficiency, lower NH₃₍g₎ concentrations in the vicinity of the birds, generation of a valuable product and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. H₂S₍g₎ removal: The main goal of this part was to develop a specific treatment process for minimizing H₂S₍g₎ emissions from hog houses. The proposed process consists of three units: In the 1ˢᵗ H₂S₍g₎ is absorbed into an acidic (pH<2) ferric iron solution and oxidized by Fe(III) to S⁰ in a bubble column reactor. In parallel, Fe(III) is reduced to Fe(II). In the 2ⁿᵈ unit Fe(II) is bio-oxidized back to Fe(III) by Acidithiobacillus ferrooxidans (AF).In the 3ʳᵈ unit S⁰ is separated from solution in a gravity settler. The work focused on three sub-processes: the kinetics of H₂S absorption into a ferric solution at low pH, the kinetics of Fe²⁺ oxidation by AF and the factors that affect ferric iron precipitation (a main obstacle for a continuous operation of the process) under the operational conditions. H₂S removal efficiency was found higher at a higher Fe(III) concentration and also higher for higher H₂S₍g₎ concentrations and lower flow rates of the treated air. The rate limiting step of the H₂S reactive absorption was found to be the chemical reaction rather than the transition from gas to liquid phase. H₂S₍g₎ removal efficiency of >95% was recorded with Fe(III) concentration of 9 g/L using typical AFO air compositions. The 2ⁿᵈ part of the work focused on kinetics of Fe(II) oxidation by AF. A new lab technique was developed for determining the kinetic equation and kinetic parameters (KS, Kₚ and mₘₐₓ) for the bacteria. The 3ʳᵈ part focused on iron oxide precipitation under the operational conditions. It was found that at lower pH (1.5) jarosite accumulation is slower and that the performance of the AF at this pH was sufficient for successive operation of the proposed process at the H₂S fluxes predicted from AFOs. A laboratory-scale test was carried out at Purdue University on the use of the integrated system for simultaneous hydrogen sulfide removal from a H₂S bubble column filled with ferric sulfate solution and biological regeneration of ferric ions in a packed column immobilized with enriched AFbacteria. Results demonstrated the technical feasibility of the integrated system for H₂S removal and simultaneous biological regeneration of Fe(III) for potential continuous treatment of H₂S released from CAFO. NH₃ and H₂S gradient measurements at egg layer and swine barns were conducted in winter and summer at Purdue. Results showed high potential to concentrate NH₃ and H₂S in hog buildings, and NH₃ in layer houses. H₂S emissions from layer houses were too low for a significant gradient. An NH₃ capturing system was designed and tested in a 100-chicken broiler room. Five bell-type collecting devices were installed over the litter to collect NH₃ emissions. While the air extraction system moved only 10% of the total room ventilation airflow rate, the fraction of total ammonia removed was 18%, because of the higher concentration air taken from near the litter. The system demonstrated the potential to reduce emissions from broiler facilities and to concentrate the NH₃ effluent for use in an emission control system. In summary, the project laid a solid foundation for the implementation of both processes, and also resulted in a significant scientific contribution related to AF kinetic studies and ferrous analytical measurements.