Dissertations / Theses: 'Flue-cured tobacco'

1

Clarke, C. Taylor. "Flue-cured tobacco : alternative management systems /." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-02132009-171607/.

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2

Brown, Emily Bruce. "Strip-till flue-cured tobacco production in Virginia." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/78737.

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Flue-cured tobacco (Nicotiana tabacum L.) is an intensively cultivated crop that typically receives four to eight primary tillage passes before being transplanted on a raised row-ridge. Strip-tillage, a conservation tillage system that only requires tilling a small strip before transplanting, has been shown to be effective for tobacco producers in southside Virginia. The cost of fertilizer in recent years and the loss of applied nutrients has brought new attention to the impact of cover crops used in conservation tillage on the nitrogen fertilization of tobacco. A two-year study conducted at the Southern Piedmont Agricultural Research and Extension Center evaluated a strip-tillage production system on agronomic performance of flue-cured tobacco and evaluated the impact of cover crop management on soil nitrogen cycling and nitrogen uptake by plants. Treatments evaluated whether a wheat cover crop was broadcast or strip killed, topdressing a wheat cover crop with 0, 22, or 45 kg ha-1, and tobacco fertilization rates. Additional treatments included a soybean residue treatment, and a conventional tillage control. Topdressing wheat with nitrogen resulted in nitrogen being released late in the growing season. Whether a wheat cover crop was strip or broadcast killed had no effect on yield or cured leaf quality. Soybean residue did not provide adequate soil cover, but was shown to be a suitable ground cover option for tobacco production. Wheat not topdressed with nitrogen and tobacco receiving normal fertilization had adequate soil surface residue cover, good cured leaf quality, and yields that were comparable to those of conventional tillage.
Master of Science

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3

Wang, Jie. "Characterizing resistance in flue-cured tobacco to Globodera tabacum solanacearum." Diss., This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-06062008-151215/.

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4

Hayes, Austin Craig. "Evaluating the potential of aerial remote sensing in flue-cured tobacco." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/90296.

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Flue-cured tobacco (Nicotiana tabacum L.) is a high value-per-acre crop that is intensively managed to optimize the yield of high quality cured leaf. Aerial remote sensing, specifically unmanned aerial vehicles (UAVs), present flue-cured tobacco producers and researchers with a potential tool for scouting and crop management. A two-year study, conducted in Southside Virginia at the Southern Piedmont Agricultural Research and Extension Center and on commercial farms, assessed the potential of aerial remote sensing in flue-cured tobacco. The effort encompassed two key objectives. First, examine the use of the enhanced normalized difference vegetation index (ENDVI) for separating flue-cured tobacco varieties and nitrogen rates. Secondly, develop hyperspectral indices and/or machine learning classification models capable of detecting Phytophthora nicotianae (black shank) incidence in flue-cured tobacco. In 2017, UAV-acquired ENDVI surveys demonstrated the ability to consistently separate between flue-cured tobacco varieties and nitrogen rates from topping to harvest. In 2018, ENDVI revealed significant differences among N-rates as early as 34 days after transplanting. Two hyperspectral indices were developed to detect black shank incidence based on differences in the spectral profiles of asymptomatic flue-cured tobacco plants compared to those with black shank symptoms. Testing of the indices showed significant differences between the index values of healthy and symptomatic plants (alpha = 0.05). In addition, the indices were able to detect black shank symptoms pre-symptomatically (alpha = 0.09). Subspace linear discriminant analysis, a machine learning classification, was also used for prediction of black shank incidence with up to 85.7% classification accuracy.
Master of Science
Unmanned Aerial Vehicle’s (UAVs) or drones, as they are commonly referred to, may have potential as a tool in flue-cured tobacco research and production. UAVs combined with sensors and cameras provide the opportunity to gather a large amount of data on a particular crop, which may be useful in crop management. Given the intensive management of flue-cured tobacco, producers may benefit from extra insight on how to better assess threats to yield such as under-fertilization and disease pressure. A two-year study was conducted in Southside Virginia at the Southern Piedmont Agricultural Research and Extension Center and on commercial farms. There were two objectives to this effort. First, assess the ability of UAV-acquired multispectral near-infrared imagery to separate flue-cured tobacco varieties and nitrogen rates. Secondly, develop hyperspectral indices and machine learning models that can accurately predict the incidence of black shank in flue-cured tobacco. Flue-cured tobacco nitrogen rates were significantly different in 2017 from 59 days after transplanting to harvest using UAV-acquired near-infrared imagery. In 2018, heavy rainfall may have led to nitrogen leaching from the soil resulting in nitrogen rates being significantly different as early as 34 days after transplanting. The imagery also showed a significant relationship with variety maturation type in the late stages of crop development during ripening. Two hyperspectral indices were developed and one machine learning model was trained. Each had the ability to detect black shank incidence in fluecured tobacco pre-symptomatically, as well as separated black shank infested plants from healthy plants.

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5

Fowlkes, Donald James. "Influence of ethephon on growth and flowering of flue-cured tobacco." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54749.

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Tobacco (Nicotiana tabacum L.) leaf initiation stops when floral induction is completed. Floral induction (an internal biochemical change which signals development of flowers) can occur prematurely, during the pre- and/or post-transplant environment. Plants which flower prematurely have few leaves and low yields. Removal of the influorescence on these plants will break apical dominance and allow production of additional leaves from axillary bud. This practice requires additional labor and increases production costs. Objectives of this study were to 1) determine how application timing, rate, localization, and on-plant duration of ethephon (2-chloroethylphosphonic acid) influences growth and flowering of flue-cured ‘NC 82’ tobacco; 2) examine the relationship between temperatures in the seedling environment and premature flowering and determine how time of plant bed cover removal affects premature flowering; and 3) quantify the ethylene released from buds, leaves, stems, and roots of tobacco seedlings at various days after application of ethephon. Ethephon applied to flue-cured tobacco seedlings before the completion of floral induction significantly reduced premature flowering and increased days to flower, number of leaf nodes per plant, and yield. Multiple applications and increased rates of ethephon did not increase the number of leaf nodes beyond the level obtained from a single application of 960 mg L⁻¹ ethephon solution applied at the rate of 44 mL m⁻² of plant bed. In wash-off studies, maximum benefit was obtained when ethephon remained on the seedlings one to two hours after application. In localization studies, increases in number of leaf nodes per plant were not different when 0.09 and 0.51 mg of ethephon was applied to the bud and largest leaf, respectively. Ethylene released from ethephon-treated greenhouse seedlings remained detectable four weeks after treatment. On-farm test locations with the two highest percentages of premature flowering had the lowest average daily minimum temperatures during the pretransplant period. Premature flowering was significantly increased at two of seven locations by removal of the perforated plastic plant bed covers two weeks compared to one week before transplanting. Floral induction of tobacco seedlings in controlled pretransplant environments was obtained by continuous 15°C temperature and 8 h photoperiods for 3 weeks.
Ph. D.

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6

Reed, Thomas David. "Quantification of tobacco aphid, Myzus nicotianae Blackman, injury to flue-cured tobacco, Nicotiana tabacum (L.) /." This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07282008-135337/.

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7

Reed, T. David. "Quantification of tobacco aphid, Myzus nicotianae Blackman, injury to flue-cured tobacco, Nicotiana tabacum (L.)." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/38956.

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A two year study was conducted to measure the impact of tobacco aphid, Myzus nicotianae Blackman, colonization and cumulative aphid-days on flue-cured tobacco, Nicotiana tabacum (L.). The objectives of the study included quantifying the response of tobacco production variables, cured leaf quality, and cured leaf chemical analysis to the level of cumulative aphid-days. Aphid populations and tobacco plant responses were recorded on an individual plant basis. A gradient in cumulative aphid-days was obtained through the use of temporally distributed aphid colonizations and selective insecticide use. Tobacco aphid populations resulted in yield reductions as great as 22 and 27% in 1988 and 1989, respectively, while gross economic returns were reduced 27 and 32% in the respective years. The responses of tobacco production variables were characterized by a decreasing negative slope; therefore, incremental losses were greatest at low levels of cumulative aphid-days. Regression models were developed to describe crop production responses as a function of cumulative aphiddays. The quality of the cured leaves (grade index) was also responsive to the level of cumulative aphid-days. Changes in both tobacco grade group and quality within a given group occurred with increasing cumulative aphid-days. The occurrence of nondescript tobacco was associated with large aphid populations. The chemical quality of the cured tobacco was also influenced by cumulative aphid-days. The total alkaloid content followed a linear function, while the level of reducing sugars was a nonlinear relationship with cumulative aphid-days. The study also reported on the disproportionate impact of aphid populations upon the within-plant responses of tobacco. A study was conducted to evaluate the impact of tobacco aphid management using eight different action thresholds. Comparison of the two most commonly recommended treatment thresholds (10 and 20% of plants with 50 or more aphids per leaf) revealed no significant differences in the number of remedial treatments required or the yield and gross economic returns. However, use of the latter threshold resulted in a delay of approximately one week for the first treatment and the retreatment interval.
Ph. D.

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8

Boaz, Robert Dale. "Design of a Pneumatic Baling System for Burley and Flue-cured Tobacco." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-05112008-145659/.

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Current tobacco baling technology utilizes hydraulic power to press tobacco into bales. The high system pressures at which hydraulic systems operate pose a risk to workers. Hydraulic systems are costly and hydraulic oil leaks contaminate baled tobacco. A pneumatically driven, vertically oriented, multi-stroke baler was designed as an affordable alternative to current hydraulic balers. Pneumatics was chosen due to the lower system operating pressure and absent risk of tobacco bale contamination. The transmission of power was achieved through a reversible pneumatic gearmotor turning left and right hand acme threaded rods coupled together to form a powerscrew. The plunger was driven by a scissor-jack design and was used to take advantage of the non-linear force response of tobacco. The scissor-jack was driven by acme nuts traveling along the acme rod of the powerscrew. The baler was tested with burley tobacco grown during the 2007 season at the Central Crops Research Station in Clayton, NC. The compressive force and plunger displacement was measured for each bale produced. These readings were used to determine the compressive force as a function of plunger travel and the compressive force as a function of bale density. The baler required 3-4 presses to produce burley bales roughly 42 inches cubed and weighing approximately 500-600 pounds.

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9

Ismail, Hasan. "An evaluation of government assistance to the Malaysian flue-cured virginia tobacco industry." Thesis, Canberra, ACT : The Australian National University, 1986. http://hdl.handle.net/1885/130376.

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The Government of Malaysia has been encouraging the modernization of the Malaysian Flue-cured Virginia (MFCV) tobacco industry, with the objective of increasing farmers' incomes and levels of living. Part of the encouragement has been in the form of regulating minimum prices and the grading structure, providing extension services and input subsidies, imposing import duties on tobacco and cigarettes, and implementing projects with advanced technologies for tobacco production. Some groups claim that the industry is receiving too much governmental assistance. Therefore, the purpose of this study is to measure the extent of the assistance. In particularly, it measured the assistance given to the tobacco growing and curing activities, both individually and jointly, for 1980 and 1984. The measurement of assistance is based on the theory of the effective rate of protection. A number of standard measures, including the Nominal Rate of Assistance, Gross Subsidy Equivalent, Effective Rate of Assistance and Net Subsidy Equivalent are employed in measuring the assistance. The methods used to derive these measures are those employed by the Australian Industries Assistance Commission which in turn are derived from the work of Balassa. The study found that, if it is assumed that all assistance flows to growers, in 1980 the growing activity received very high assistance: the estimated effective rate of assistance was 1,232 per cent. The effective rate of assistance for 1984 was not calculated due to the negative value-added, implying even higher assistance. Under this assumption, the estimated effective rates of assistance for the curing activity were -12.44 and -3.6 per cent for 1980 and 1984 respectively, implying the activity was taxed by the community. With the assumption that the assistance was fully retained by curers, the assistance given to the growing activity in 1980 and 1984 was low with the estimated effective rates of assistance being 22.06 and 14.92 per cent respectively. The effective rates of assistance for the curing activity in these years were not calculated due to the negative value-added, implying very high assistance. The study found that the assistance given to the joint activity of tobacco growing and curing for 1980 and 1984 was high: the estimated effective rates of assistance were 107.34 and 169.64 respectively. It is concluded that, probably, the estimated assistance of the joint activity is most indicative of assistance received by growers and curers in these years. Comparisons with other studies suggest that the rates of assistance given to the joint activity of tobacco growing and curing in 1980 and 1984 were generally far higher than that for other agricultural activities in 1973, in particularly for smallholder rubber, oil palm, coconut, livestock, food crops and total primary industry. The rates were also far higher than that for several agricultural activities in 1977, in particularly smallholder rubber, oil palm, cocoa, cocoa-coconut (intercropping) and rice.

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10

Ellis, Madeleine D. "Quantitative analysis of individual flue-cured tobacco seed tissues reveals Tobacco mosaic virus infection in embryos." Thesis, Virginia Tech, 2019. http://hdl.handle.net/10919/101554.

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Tobacco mosaic virus (TMV) is an extensively studied RNA virus that reduces quality and yield in commercially grown tobacco (Nicotiana tabacum L.). The virus is transmitted mechanically, although infections have been associated with contaminated seeds with the seed coat being the source of virus. Thus, TMV transmission is said to be seedborne (as opposed to true seed transmission where the embryo is infected). The objective of this study was to identify TMV concentrations in the three components of an individual tobacco seed: seed coat (SC), endosperm (ED), and embryo (EM). Six hundred seed from TMV infected K 326 flue-cured cultivar tobacco plants were carefully dissected into the three components. Total RNA was extracted from each sample and synthesized into cDNA for analysis. A quantitative real-time PCR (RT-qPCR) assay was developed to quantify viral titers in each component, while endpoint PCR confirmed RT- qPCR results and established a threshold viral cycle (Ct) value. Endpoint PCR results revealed viral accumulation in all three components of a tobacco seed. The highest concentration of TMV was in the SC, followed by ED and EM. A similar viral concentration gradient was observed in each individual tobacco seed from all three experimental plants. This is the first detection of TMV in tobacco embryos and suggests the virus can be seed transmitted.
Master of Science

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11

Brown, Robert T. "Evaluating the use of renewable fuel sources to heat flue-cured tobacco barns." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/82554.

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The curing of flue-cured tobacco (Nicotiana tabacum L.) is an energy intensive process and represents a significant portion of the overall cost of production. Given the goal of the industry to reduce the environmental footprint of tobacco production and the energy demand of curing, attention has been directed to explore options for the use of renewable fuels for heating tobacco barns. A two-year study conducted at the Virginia Tech Southern Piedmont Center evaluated the effectiveness and cost of curing flue-cured tobacco with a wood pellet burner. Additionally, field studies were conducted to evaluate the feasibility of on-farm production of biomass fuel crops as well as on-farm manufacture of biomass fuel pellets. The first time use of a wood pellet burner with an air-to-air heat exchanger in a bulk curing barn proved to be a viable alternative to a conventional propane fueled burner. Curing cost averaged $0.05 with the pellet burner compared to $0.04 per kilogram of tobacco with the propane burner. The increase in cost was offset by a 90 percent reduction of CO2 emissions with the use of wood pellets. The use of low lignin grass varieties did have an impact on biomass pellet properties. Pellet testing revealed high ash and chloride levels which could be problematic using a high efficiency wood pellet burner. Full maturity harvest of annual grasses fertilized with 112 kg per ha N resulted in higher yields. However, fertilizing for maximum yield would increase the CO2 footprint for biomass fuel pellet production.
Master of Science

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12

Syracuse, Aaron James. "Intraspecific Variability within Globodera tabacum solanacearum and Selection for Virulence Against Flue-Cured Tobacco." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/35515.

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The tobacco cyst nematode (TCN), Globodera tabacum solanacearum [(Miller and Gray, 1972) Behrens 1975] Stone 1983, is one of the most economically important pests of flue-cured tobacco (Nicotiana tabacum L.) in Virginia. Although TCN has been reported from other countries, the geographical distribution of G. t. solanacearum within the United States is limited to Virginia, North Carolina, and one county in Maryland. Approximately 30% of the tobacco acreage in Virginia is infested; average yield reduction is 15%, but complete crop failure can occur. The objectives of this research were to examine intraspecific variability within G. t. solanacearum and to evaluate the relative adaptability of G. t. solanacearum on a resistant (NC567) and a susceptible (K326) flue-cured tobacco cultivar. Nineteen geographic isolates of G. t. solanacearum, one isolate each of G. t. virginiae and the Mexican cyst nematode (G. "mexicana"), two isolates of G. t. tabacum, and five Heterodera species were characterized by DNA fingerprinting using the RAPD-PCR technique. Reproducible differences in fragment patterns allowed similar differentiation of the isolates and species with each primer. Hierarchical cluster analysis was performed to illustrate the relatedness between nematode isolates and species. In contrast to reports in the literature, we found a Miller isolate of G. "mexicana" to cluster more closely with G. t. solanacearum than with G. t. tabacum or G. t. virginiae. Although no pathotype differences have been found within G. t. solanacearum, the average Jaccard's similarity index among isolates of G. t. solanacearum was 74%, representing greater variation than that observed across different pathotypes of the closely related potato cyst nematode, Globodera pallida. This result suggests that the emergence of resistance-breaking biotypes is more likely than previous research suggests. If a new pathotype is reported, a RAPD marker associated with virulence against a specific host resistance gene could prove to be a valuable tool in population diagnosis, resistance screening, and overall TCN management. One isolate of G. t. solanacearum was cultured on a resistant (NC567) and a susceptible (K326) flue-cured tobacco cultivar over five generations. Variable TCN reproduction was observed on both cultivars over each generation. This variability in reproduction could be attributed to differences among generations in the time interval between inoculation and cyst extraction, temperature, possible diapause effects, and/or daylength. Ninety-eight cysts were produced in the fifth and final generation compared to the 14 to 50 cysts produced during each of the previous four generations. Increased reproduction on the resistant variety suggests that increased virulence might be selected, but research involving additional generations would need to be carried out in order to conclude whether or not TCN virulence is being selected.
Master of Science

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13

Hamid, Mohd Norowi Bin. "Effect of predators on population dynamics of green peach aphid on flue-cured tobacco in Virginia." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/53128.

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The effects of indigenous predators on green peach aphid (GPA), Myzus persicae (Sulzer), populations on flue-cured tobacco were evaluated in 1985 and 1986. The most common GPA predators found on tobacco were convergent lady beetle (CLB) (Hippodamia convergens), syrphid flies, Geocoris spp., Jalysus wackhimi, Nabis spp., Chrysopa spp., Micromus sp., and several other species coccinellids. However, CLB was the only predator that had a numerical response to increasing GPA density on tobacco. In the laboratory, the minimum number of GPA required to initiate reproduction in CLB, and the conversion rates were two factors that determined the oviposition rate of CLB. In fields, CLB demonstrated a sigmoid curve predator-prey relationship. CLB did not show a linear relationship until GPA populations reached a certain density. Furthermore, CLB did not show a response when GPA density was above the satiation point. Although CLB were able to reduce GPA population growth, they were not able to maintain GPA populations below the economic injury level. Two factors probably limited the success of CLB to control GPA populations on flue-cured tobacco: 1.) the glandular trichomes of tobacco which produced gummy exudates, and 2.) the satiation point of CLB when GPA populations were very high. In addition, interplanting tobacco with clover increased the number of syrphid fly larvae on tobacco. Likewise, tobacco interplanted with sunflowers had increased big-eyed bug, populations, and tobacco-alfalfa and tobacco-tobacco plots had higher stilt bug populations on tobacco.
Master of Science

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14

Jones, Bruce. "Impact of Conservation Tillage on Soil Erosion and the Agronomic Performance of Flue-Cured Tobacco." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/40537.

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Conservation tillage tobacco production has gained little producer acceptance since introduction in the late 1960's. Yield reductions, tobacco quality issues, unacceptable weed control, and inadequate planting equipment limited practice adoption and substantiated the need for continued research. The recent developments of a Subsurface Tiller-TransplanterTM and the herbicide SpartanTM renewed producer interest in conservation tillage and led to an investigation with both flue-cured and Virginia dark-fired tobacco. Flue-cured tobacco was transplanted into rye mulch on bedded rows and subsequently cultivated at various timings. Conservation tillage significantly reduced soil erosion approximately 92 percent and tobacco yield approximately 23 percent when row cultivation was not applied. Row cultivation significantly increased tobacco yield without increasing soil erosion. The yield of conservation tillage tobacco receiving a minimum of two cultivations was similar to conventional tobacco. The second study evaluated wheat, rye, crimson clover, and mixtures of crimson clover with either wheat or rye as cover crop mulches for conservation tillage production of Virginia dark-fired tobacco. Conservation tillage, regardless of cover crop, reduced dark-fired tobacco yields approximately 779 and 488 pounds per acre in 1996 and 1997, respectively. The removal of cover crop residue for hay did not lower tobacco yield compared to leaving residue on the soil surface. Row cultivation increased conservation tillage tobacco yield approximately 247 pounds in 1997 regardless of cover crop. The nitrogen contribution of crimson clover was minimal in both years of the study and did not affect tobacco performance.
Master of Science

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15

Long, Robert Sherman. "Influence of nitrogen rate, harvest frequency, lower leaf management, and chemical topping on mammoth cultivars of flue-cured tobacco." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/43096.

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Mammoth cultivars of tobacco do not flower under normal production conditions. A field management system must be devised for these cultivars to optimize agronomic traits and chemical constituents of the cured leaf. Field experiments were conducted at the Southern Piedmont Agricultural Experiment Station near Blackstone, Virginia in 1987 and 1988 to determine the influence of nitrogen rate, harvest frequency, and time and number of basal leaf removal on several agronomic and chemical properties of a mammoth cultivar of flue-cured tobacco. The feasibility of chemically topping two mammoth cultivars was also investigated. Increasing nitrogen rates increased values per hectere by $176 and total alkaloids by 0.5% in 1987. Increasing the number of harvest increased percentage lugs (X) and reducing sugars for stalk position B in 1988 but decreased reducing sugars for stalk positions A and C in 1988. Delaying leaf removal increased yield and values per hectare by 141 kg ha^-1 and $84, respectively, and decreased lug production in 1987 and 1988. Total alkaloids decreased by 0.7% with delayed leaf removal in 1987. Delayed leaf removal increased reducing sugars at stalk position A by 2% in 1988. Removing fewer basal leaves increased yields by 115 kg ha^-1, values per hectare, and percentage smoking leaf (H) for both years. Alkaloids for stalk position B increased with fewer basal leaves removed in 1988. Decreased basal leaf removal decreased plant height by 9 cm, percentage leaf (B), and reducing sugars in stalk positions A, B, and D in 1988. Delaying basal leaf removal and decreasing harvest frequency increased the percentage of cutters (C). Percentage smoking leaf increased with nitrogen rate and removal of fewer basal leaves. Chemical topping created taller plants with more leaves, narrower tip leaves, lower total alkaloids, and equal or higher reducing sugars relative to hand topping. Tip leaves from chemically topped plants were 6 to 8 cm shorter than hand-topped plants in 1987. Maleic hydrazide treatments resulted in 429 to 700 kg ha^-1 lower yields and lower values than hand topping and 6 more suckers than all other treatments. The fatty alcohol / maleic hydrazide treatment produced 380 kg ha^-1 higher yields and grade indices lower than the hand-topped control in 1987. Above normal nitrogen rate, 3 or 5 time harvest, removal of 4 to 6 leaves at topping or via senescence, and chemical topping with Prime+ or fatty alcohol / maleic hydrazide tank mix provided the best field management system for mammoth cultivars under the conditions of this study.

Master of Science

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16

Morris, Jerry Whitaker. "Influence of nitrogen fertilization and leaf management on nitrogen use efficiency and agronomic performance of mammoth cultivars of flue-cured tobacco /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-08182009-040605/.

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17

Mullins, Seth David. "Influence of cultivar, topping height, and harvest treatment on physical and chemical characteristics of flue-cured tobacco." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/41004.

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There has been an increased interest among the tobacco industry in the production of tip leaves in flue-cured tobacco. Different harvest treatments of flue-cured tobacco were compared across six cultivars and two topping heights with the objective of identifying tip grade tobacco. Agronomic and cured leaf chemistry data were collected. Cultivar had significant influences on yield, average price, grade index, and value in three growing seasons. NC 71 and RG H51 were the highest yielding cultivars, with grade indices among the highest as well. Increasing topping height increased tobacco yield in two of three years. As topping height increased there was a significant increase in the percentage of tobacco receiving a tip grade. The four harvest treatments focused on the ten uppermost leaves of the plant. Harvest treatments that allowed proper separation of stalk positions (5&5L and 7&3L treatments) resulted in increased yields and tip grades. Harvest treatments that separate upper stalk position tobacco resulted in a higher percentage of tip grades from a tobacco company grader. Chemical analysis identified differences between stalk positions at the top of the plant. In order for cigarette manufacturers to properly blend the tobacco used to make American blend cigarettes, this separation of stalk positions is important. Harvest treatments that combined stalk positions resulted in the loss of these chemical differences. By topping flue-cured tobacco four to five leaves higher than current extension recommendations and separating stalk positions correctly, tobacco growers can meet the crop throw requirements of tobacco marketing contracts.
Master of Science

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18

Rideout, James W. "Influence of nitrogen source and metalaxyl on nitrification in soils and the yield and quality of flue-cured tobacco." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91145.

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Numerous Investigators have reported that NH₄⁺ uptake reduces the yield and quality of flue-cured tobacco (Nicotiana tabacum L.). Metalaxyl, a fungicide commonly used in the production of flue-cured tobacco, has been patented as a nitrification inhibitor. The objectives of this study were to 1) determine the influence of metalaxyl at commonly applied rates on the + nitrification of NH₄⁺ from various sources; 2) study the Influence of soil pH on inhibition of nitrification by metalaxyl; 3) study the Influence of N source and metalaxyl on N accumulation in the plant; and 4) evaluate the influence of N source and metalaxyl on the yield, quality, and chemical composition of flue-cured tobacco leaf. Field, greenhouse, and laboratory experiments were conducted in the Southern Piedmont region of Virginia in 1984 and 1985 to carry out these objectives. Metalaxyl was found to reduce the population of NH₄⁺ oxidizers in soil and inhibit nitrification at applications of 0.56, 1.12, and 3.36 kg ha⁻¹. The inhibitory effects of metalaxyl were much weaker than nitrapyrin. Nitrification was inhibited by metalaxyl only in soils where nitrification was slowed by low pH and wet conditions. In soils of high nitrifying capacity, metalaxyl did not inhibit nitrification. Nitrogen uptake was enhanced by high NO₃⁻ concentrations in the soil, except where metalaxyl reduced NO₃⁻ leaching. Cured leaf concentrations of N were not affected by N source but were slightly reduced by metalaxyl. Nitrogen source and metalaxyl did not affect yield, total alkaloids, or reducing sugars. Quality Index was reduced by decreased soil NO₃⁻ from both N source and metalaxyl.
M.S.

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19

Adamo, Noah R. "Reproduction of the root-knot nematode Meloidogyne arenaria on flue-cured tobacco possessing resistance genes Rk1 and/or Rk2 and the impact of parasitism on the accumulation of nicotine in conventional and low-alkaloid tobacco." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/104221.

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Host resistance has become a cornerstone of sustainable production of flue-cured tobacco in regions where root-knot nematodes present a threat to growers. Resistance to races 1 and 3 of M. incognita, historically the most significant root-knot nematode threat to tobacco production, is now widely available in commercially available flue-cured tobacco varieties, and is imparted by the gene Rk1. The same gene also provides resistance to race 1 of M. arenaria. The widespread deployment of this resistance has fostered a shift in root-knot nematode population dynamics, as a result of which M. arenaria race 2 has become the predominant root-knot nematode threat in Virginia. A second resistance gene known to impart resistance to M. javanica, Rk2, has also been incorporated into numerous released cultivars in combination with Rk1. This combination has been demonstrated to impart increased resistance to M. incognita and M. javanica relative to either gene alone. In the present work, eleven greenhouse trials conducted from 2017-2019, as well as two trials conducted in 2018 and 2019 on a cooperating farm, investigated the efficacy of this stacked resistance against M. arenaria race 2 and compared the effect of stacking both resistance genes to the effect of either gene alone relative to a susceptible cultivar. We also evaluated how these forms of resistance compare with resistance possessed by a breeding line with resistance reportedly derived from N. repanda to determine if additional, novel sources of resistance to root-knot nematodes previously identified from other species in the genus Nicotiana could play a role in expanding the genetic diversity of germplasm available for the refinement of host resistance in flue-cured tobacco. Additionally, in light of potential new rule making from the FDA mandating reduced nicotine content of cured tobacco leaf, we investigated the relationship between alkaloid (nicotine) content of flue-cured tobacco and root-knot nematode parasitism, while also evaluating nematode parasitism effects on carbohydrate content. Despite considerable variability in our results, particularly under field conditions, our results demonstrate that stacking Rk1 and Rk2 imparts greater resistance to M. arenaria race 2 than either gene alone, but that an entry possessing resistance reportedly derived from N. repanda exhibited significantly greater resistance to root-knot nematodes than the combination of Rk1 and Rk2 based on root galling, and egg mass and egg production. The alkaloid content of flue-cured tobacco did not appear to have an effect on root-knot nematode parasitism under greenhouse or field conditions, but the presence of the nematode did lead to increased accumulation of nicotine in the roots of plants, while translocation of nicotine to leaves was reduced. Conversely, root-knot nematode parasitism was reduced accumulation of carbohydrates in roots, while having no significant effects on leaf carbohydrate content.
Ph.D.
Root-knot nematodes (Meloidogyne spp.) are microscopic round worms that can cause considerable damage to flue-cured tobacco (Nicotiana tabacum L.), and while not typically responsible for killing plants outright, can reduce the quality of cured tobacco leaf and may predispose plants to a host of other issues, resulting in challenges and economic burdens on growers. Chemicals that effectively control nematodes, which are animals, pose inherent threats to human applicators and may harm the environment in a number of ways, so the use of tobacco varieties that are resistant to root-knot nematodes is increasingly common and essential to sustainable tobacco production. One form of root-knot nematode resistance, called Rk1, has become common and is found in all commercially grown flue-cured tobacco. This form of resistance is effective against 2 ‘races’ of the root-knot nematode M. incognita, which has historically caused tobacco growers the most issues. However, because this resistance is so widely employed, growers have controlled these nematodes, while another species, M. arenaria, has become more prevalent, particularly ‘race’ 2, which is not controlled by Rk1. We know from previous research that another gene, Rk2, provides resistance to some root-knot nematode that Rk1 does not effect, and that combining both genes seems to provide even greater root-knot nematode control than either gene alone. We investigated whether Rk2 is effective at controlling M. arenaria race 2 when it is combined with Rk1 in greenhouse and field experiments. We also investigated how a different, novel type of resistance, which comes from a species of tobacco related to cultivated tobacco, compares with the Rk1/Rk2 resistance in greenhouse trials. Additionally, the FDA has recently suggested that nicotine levels in tobacco leaf should be dramatically reduced to help mitigate adverse human health consequences associated with tobacco consumption. Nicotine may play some role in resistance to root-knot nematode in tobacco, and conversely, root-knot nematodes may impact levels of nicotine, as well as other important chemical constituents of tobacco. We also investigated these questions in greenhouse and field experiments. Our results ultimately demonstrate that combining both Rk1 and Rk2 gives flue-cured tobacco a higher level of resistance to root-knot nematodes than either gene alone, but also suggests that the form of resistance we evaluated from a related Nicotiana species could be even more effective in controlling these nematodes. We observed that the amount of nicotine present in tobacco did not impact nematode parasitism, but that nematode parasitism could lead to lower levels of nicotine in the leaves of plants because the nematodes, which feed on plants roots, cause damage to the plant that interferes in the movement of nicotine from roots to leaves.

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Morris, Jerry Whitaker. "Influence of nitrogen fertilization and leaf management on nitrogen use effeciency and agronomic performance of mammoth cultivars of flue-cured tobacco." Thesis, Virginia Tech, 1993. http://hdl.handle.net/10919/44303.

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Wise, William B. "Short-term employment, income and output consequences of a decline in flue-cured tobacco production : the case of Southside Virginia /." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-08252008-162955/.

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22

Rideout, Steven Lewis. "The Effect of Nematode Isolate and Soil Environment on the Tobacco cyst Nematode (Globodera tabacum solanacearum), a Pathogen of Flue-cured Tobacco and Other Solanaceous Crops." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/36056.

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Tobacco cyst nematodes (TCN), Globodera tabacum solanacearum, are one of the most serious pests for Virginia flue-cured tobacco (Nicotiana tabacum L.) farmers. These nematodes continue to spread to new farms every year and are now reported in 11 Virginia counties, seven North Carolina counties, and one farm in Maryland. The objectives of this study were to determine the ability of different populations of TCN to reproduce upon both a susceptible (K326) and resistant (NC567) cultivar, to compare TCN reproduction in non-infested soils with currently TCN-infested soils, and to examine reproduction and pathogenicity of TCN on other solanaceous crops.

Tobacco cyst nematode reproduction on the TCN-resistant cultivar NC567 was significantly reduced when compared to the TCN-susceptible cultivar K326. Although significant differences among the populations were detected on both cultivars, the differences were not consistent across experiments. Results indicate similar pathogenicity among TCN populations on resistant and susceptible flue-cured tobacco cultivars. Plant breeders may use one population of the tobacco cyst nematode to screen tobacco germplasms for TCN resistance.

Significant differences were noted in TCN reproduction among the various soils used in this study. However, the differences were inconsistent, making correlations between TCN reproduction and soil edaphic characteristics unreliable. Sterilizing the soils did not increase TCN reproduction. Reproduction in non-infested soils indicates that TCN will continue to spread throughout tobacco producing regions.

Although traditionally an exclusive pest of tobacco, TCN's spread may threaten production of other solanaceous crops. Eggplant (Solanum melongena L.), pepper (Capsicum spp. L.), and tomato (Lycopersicon spp. L.) were confirmed to be hosts of TCN under field conditions. Eggplant was highly susceptible to TCN reproduction and yield suppression, exhibiting a 64% yield reduction in plots not treated with a nematicide compared to fumigated plots. Tomato allowed high rates of TCN reproduction but did not suffer yield loss. Tobacco cyst nematode reproduction was suppressed on pepper compared to the other two crops. No crop loss was noted in nontreated pepper plots compared to plots treated with a nematicide. Results would indicate that tobacco rotations including tomato or eggplant would be unacceptable due to high TCN reproduction rates. The tobacco cyst nematode does not seem to jeopardize the production of tomato and pepper in the southeastern United States, but does threaten profitability of eggplant production in this area.
Master of Science

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23

Pollok, Jill. "Reproduction of a root-knot nematode population on flue-cured tobacco homozygous for Rk1 and/or Rk2 resistance genes and the effect of soil temperature on resistance gene efficacy." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/56597.

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Utilizing resistant cultivars is a main control strategy for root-knot nematodes in flue-cured tobacco (Nicotiana tabacum L.). Most commercial cultivars possess the Rk1 gene, providing resistance to races 1 and 3 of Meloidogyne incognita and race 1 of M. arenaria. This initiated a shift in root-knot populations to other species and races, creating a need for resistance to those populations. Numerous cultivars possess a second resistance gene, Rk2. Greenhouse experiments investigated whether possessing both Rk1 and Rk2 increases resistance to a variant of M. incognita race 3 compared to either gene alone, and if high soil temperatures impact their efficacy. Root galling, numbers of egg masses and eggs, and the reproductive index were compared from roots of Coker 371-Gold (susceptible), NC 95 and SC 72 (Rk1Rk1), T-15-1-1 (Rk2Rk2), and STNCB-2-28 and NOD 8 (Rk1Rk1 and Rk2Rk2). The same data were analyzed from plants in open-top root zone cabinet growth chambers set to 25ºC, 30ºC, and 35ºC to examine if resistance is temperature sensitive. Despite variability, Rk1Rk2 entries conferred greater resistance than entries with Rk1 or Rk2 alone. Entries with Rk1 alone reduced galling and reproduction compared to the susceptible control, whereas T-15-1-1 (Rk2) did not, but often suppressed reproduction. An apparent reduction in nematode reproduction was observed at 25ºC and 30ºC on entries possessing Rk1 and Rk1Rk2 compared to the control and Rk2. However, no apparent differences in reproduction occurred on Rk1 and/or Rk2 entries at 35ºC compared to the control, indicating parasitism increased on resistant entries at higher temperatures.
Master of Science in Life Sciences

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Mulekano, Office Locarno Pious. "Evaluation of elite breeding lines of flue-cured tobacco for field and market performance." Diss., 1999. http://hdl.handle.net/2263/30318.

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Please read the abstract in the section 00front of this document
Dissertation (M Inst Agrar (Sustainable Plant-Genetic Resource Management))--University of Pretoria, 2006.
Genetics
unrestricted

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Lawrence, Jessica L. "Damage relationships and control of the tobacco splitworm (Gelechiidae: Phthorimaea operculella) in flue-cured tobacco." 2009. http://www.lib.ncsu.edu/theses/available/etd-10312009-184805/unrestricted/etd.pdf.

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Gaddy, Joshua Andrew. "The influence of variety on mechanical harvesting efficiency of flue-cured tobacco." 2004. http://www.lib.ncsu.edu/theses/available/etd-01032005-132419/unrestricted/etd.pdf.

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Edwards, Patrick Boddie. "The effect of management practices on grade distribution in flue-cured tobacco." 2005. http://www.lib.ncsu.edu/theses/available/etd-03242005-142941/unrestricted/etd.pdf.

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Ellington, Grant Hual. "Investigation into the correlation among nitrogen oxides and TSNAs in flue-cured tobacco." 2008. http://www.lib.ncsu.edu/theses/available/etd-11032008-112840/unrestricted/etd.pdf.

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Mandanna, P. K. "An analysis of supply, price and trade of flue cured virginia tobacco in India." Thesis, 1998. http://hdl.handle.net/2009/1338.

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Taylor, Zachary Graham. "Effects of the ethylene binding inhibitor 1-methylcyclopropene on flue-cured tobacco (Nicotiana tabacum L.)." 2009. http://www.lib.ncsu.edu/theses/available/etd-11132008-092540/unrestricted/etd.pdf.

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Parker, Robert Gary. "Evaluation of nitrogen sources and rates on yield and quality of modern flue-cured tobacco cultivars." 2009. http://www.lib.ncsu.edu/theses/available/etd-11172008-145003/unrestricted/etd.pdf.

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Taylor, Zachary Graham. "Management of axillary shoot growth and maleic hydrazide residues with diflufenzopyr in flue-cured tobacco (Nicotiana tabacum)." 2005. http://www.lib.ncsu.edu/theses/available/etd-03312005-125020/unrestricted/etd.pdf.

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Wilkinson, William Charles. "Effects of stand loss, planting date, and replanting method on yield and quality of flue-cured tobacco." 2005. http://www.lib.ncsu.edu/theses/available/etd-03202005-113610/unrestricted/etd.pdf.

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Cherry, Kathryn Renee. "Investigation of in season progression of Tomato spotted wilt virus and its management in flue-cured tobacco fields of North Carolina." 2009. http://www.lib.ncsu.edu/theses/available/etd-07012009-150451/unrestricted/etd.pdf.

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Dissertations / Theses on the topic 'Flue-cured tobacco'

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