Browsing by Author "Randy Wells, Member"

Now showing 1 - 13 of 13

Effects of Soil Tillage on Flue-cured Tobacco Growth, Weed Control, and Soil Physical Properties.
(2015-02-27) Vann, Matthew Christopher; Loren Fisher, Chair; Kenneth Esbenshade, Graduate School Representative; Randy Wells, Member; Alexander Stewart, External; David Jordan, Member; Joshua Heitman, Member
Evaluation of Nitrogen Application Timings on Yield, Quality, and Sucker Control.
(2014-05-07) Drake, Matthew Paul; Loren Fisher, Chair; William Smith, Member; Randy Wells, Member
Fertility Management and Variety Mixtures of Cotton in North Carolina.
(2020-09-08) Szilvay, Blake Lindley; Keith Edmisten, Co-Chair; Guy Collins, Co-Chair; Randy Wells, Member
Genetic Diversity Analysis and Mapping of Fiber Quality and Flowering Time Traits in Tetraploid Cotton.
(2018-11-06) Zhu, Linglong; Vasu Kuraparthy, Chair; Imara Perera, Graduate School Representative; Randy Wells, Member; Gina Brown-Guedira, Member; Jose Alonso, Member
Impact of Ruminant Digestion on Germination of Ingested Seeds of Native Warm-Season Grasses and Agronomic Weed Species in the Southeast United States.
(2014-03-21) Kiley, Erin R; Lori Unruh Snyder, Chair; Wesley Everman, Member; Randy Wells, Member
The Impacts of Athletic Field Paint on Light Spectral Quality, Turfgrass Photosynthesis and Transpiration in Painted Turfgrass Canopies.
(2013-04-15) Reynolds, William Casey; Grady Miller, Co-Chair; Thomas Rufty, Co-Chair; Randy Wells, Member; David Livingston, Member; Michael Paesler, Member; Michael Hyman, Graduate School Representative
Improving Cotton (Gossyipium hirsutum L.) Production through Non-Traditional Agricultural Practices.
(2012-06-15) Foote, William Ray; Keith Edmisten, Chair; Loren Fisher, Member; Gary Roberson, Member; Randy Wells, Member; Jack Bacheler, Member; David Jordan, Member; Russel Nuti, External; Ross Whetten, Graduate School Representative
Influence of Environmental Factors on Broadleaf Signalgrass (Brachiaria platyphylla) and Crowfootgrass (Dactyloctenium aegyptium) Germination and Antagonism of Clethodim by CGA 362622 and Imazapic.
(2002-04-22) Burke, Ian Cristofer; John W. Wilcut, Chair; Janet F. Spears, Member; David Monks, Member; Randy Wells, Member
Laboratory and greenhouse studies were conducted to determine the effect of temperature, solution pH, water stress, and planting depth on broadleaf signalgrass and crowfootgrass germination. Onset, rate, and total broadleaf signalgrass germination (87%) was greatest in alternating 20/30 C temperature regime, while onset, rate, and total crowfootgrass germination (95%) was greatest in an alternating 20/35 C temperature regime. For both species, germination decreased as solution pH increased, with greatest germination occurring at pH 4 and 5. Germination of both species decreased with increasing water potential, and no germination occurred below -0.8 mPa. Germination decreased with burial depth. No seed of either species emerged from 10 cm. Field and greenhouse experiments were conducted to evaluate clethodim applied alone, in mixture and sequential treatments of clethodim plus CGA 362622 or imazapic for control of broadleaf signalgrass, fall panicum, goosegrass, and large crabgrass. Clethodim alone controlled broadleaf signalgrass, goosegrass, fall panicum and large crabgrass >93%, regardless of rate, while CGA 362622 did not control grasses in greenhouse or field experiments. Imazapic provided <82% control of grass weeds. When CGA 362622 or imazapic were applied in mixture with clethodim the effectiveness of the graminicide was reduced for all annual grasses. Clethodim applied 7 d before or after CGA 362622 or imazapic controlled the four grass species as well as clethodim applied alone. Therefore, while antagonism was variable, it usually occurred when ≤3 d separated applications of clethodim and CGA 362622 or imazapic. CGA 362622 or imazapic did not affect absorption, translocation, or metabolism of 14C-clethodim by goosegrass. When CGA 362622 was applied to goosegrass, fresh weight accumulation stopped for a period of 4 d compared to nontreated plants. Growth resumed 4 d after application of CGA 362622. One day after treatment, the photosynthetic rate in plants treated with CGA 362622 or imazapic was less than non-treated goosegrass. Photosynthetic rate of goosegrass was less for a period of 6 d after treatment with CGA 362622. Goosegrass photosynthetic rate did not recover when treated with imazapic. These data suggest that the antagonism of clethodim by CGA 362622 and imazapic may result from CGA 362622 or imazapic altering the sensitivity of ACCase to clethodim.
Linkage Map Construction and QTL Analyses for Fiber Quality, Yield and Agronomic Traits using 63K Array-based SNPs in Upland Cotton (Gossypium hirsutum L.).
(2019-02-28) Zhang, Kuang; Vasu Kuraparthy, Chair; Gina Brown-Guedira, Member; Randy Wells, Member
Monoecious Hydrilla and Crested Floating Heart Biology, and the Response of Aquatic Plant Species to Florpyrauxifen-benzyl Herbicide.
(2018-03-19) Haug, Erika Jeanne; Robert Richardson, Chair; Michael Netherland, Member; William Cope, Minor; Randy Wells, Member; Ramon Leon Gonzalez, Member; Mari Chinn, Graduate School Representative
Physiological and Morphological Basis for Reproductive Sensitivity to Glyphosate in Glyphosate-Resistant Cotton.
(2002-03-25) Pline, Wendy; John W. Wilcut, Co-Chair; Keith L. Edmisten, Co-Chair; Randy Wells, Member; Ronald Sederoff, Member; Judith Thomas, Member; Stephen O. Duke, Member
Transgenic, glyphosate-resistant (GR) cotton has been available to U.S. growers since 1997. Despitewide-spread acceptance, there have been performance complaints by growers citing lower boll retention in GRvarieties than in conventional varieties. Field and greenhouse studies confirmed grower observations,demonstrating a glyphosate-associated decrease in boll retention compared to non-treated GR or conventionalplants. Late (beyond the 5 leaf stage) foliar applications were the most injurious, presumably because plantswere entering early reproductive stages. Boll 'cavitation,' (dessicated bolls attached to plants) also observed bygrowers following glyphosate treatment, resulted from abnormal abscission zone formation and was related tovariety. 14C-glyphosate absorption per square centimeter was greater when applied to stem tissue than leaf tissue, but overallabsorption is likely greater when applied foliarly, due to a greater total surface area. Because glyphosatetypically moves from source tissue to sink tissue, up to 3.7% of applied 14C-glyphosate was translocated toreproductive tissues. Seedling development in both GR and conventional cotton was inhibited by root-absorbed glyphosate.Root tissues were more sensitive to glyphosate than cotyledons or hypocotyls, as was demonstrated byinhibition of lateral root formation and shikimic acid accumulation. CP4-EPSPS content was significantly lowerin GR seedling roots than cotyledons, accounting for glyphosate sensitivity. Further studies compared the accumulation of shikimic acid in response to glyphosate in reproductiveand vegetative tissues in GR and conventional cotton. Shikimic acid accumulation per mM of glyphosate, wasgreater in reproductive than vegetative leaf tissue in both GR and conventional cotton, suggesting thatreproductive tissue is innately more sensitive to glyphosate than vegetative tissue. The quantity of theglyphosate-resistant CP4-EPSPS enzyme was significantly less in stamens than in vegetative leaf tissues.Several morphological differences were apparent in flowers of glyphosate-treated GR cotton. Glyphosate applications inhibited stamen elongation, resulting in anthers not extending to the tip of the stigma,thereby limiting pollen deposition to the lower, less receptive portion of the stigma. Total pollen deposition on the stigma was less in glyphosate-treated GR cotton than non-treated GR or conventional cotton. Microscopicanalysis of pollen revealed that glyphosate arrested maturation in at least 3 pollen developmental stages. Atanthesis, pollen grains from glyphosate-treated GR plants were collapsed, highly vacuolated, and had 60% lowerviability (ability to germinate) than pollen from non-treated GR or conventional plants. Retained bolls fromglyphosate-treated plants had fewer seeds than those from non-treated GR or conventional plants. Hand crossesbetween glyphosate-treated plants demonstrated that the number of seeds per boll was decreased when the maleparent, but not the female parent, was glyphosate treated. Hand pollinations using pollen from treated plants,although overcoming the increased anther-stigma distance, did not restore the normal number of seeds per boll.Treatment of GA onto glyphosate-treated GR plants did not remediate glyphosate effects on pollen viability andfloral morphology. Therefore, presumably, several of the bolls that were shed due to glyphosate-treatments,contained an insufficient number of fertilized ovules and are thus shed. This research proposes that boll shed due to glyphosate in GR cotton is due to insufficient levels ofCP4-EPSPS in stamens, which are highly sensitive to glyphosate. As glyphosate accumulates in reproductivestructures, stamen elongation and pollen development are inhibited, resulting in poor fertilization of ovules. Because fewer ovules are fertilized, bolls are either shed or contain fewer seeds if retained. Growers shouldlimit glyphosate contact with GR cotton, especially during the reproductive stages in order to minimize thepotential for glyphosate-induced boll shed.
The Effect of Lower Leaf Removal Number, Leaf Removal Timing, and Nitrogen Application Rate on the Yield, Quality, Value, and Crop Throw of Flue-cured Tobacco.
(2018-04-18) Finch, Camden Elmo; Matthew Vann, Chair; Loren Fisher, Member; Randy Wells, Member; Alvin Brown, Member
Upland Cotton Growth and Yield Response to the Interactions of Planting Date with Irrigation Strategies, Soil Tillage Systems, and Agronomic Inputs.
(2017-04-17) Spivey, Todd Alan; Keith Edmisten, Chair; Randy Wells, Member; Joshua Heitman, Member; Francois Birgand, Graduate School Representative; Gail McRae, Member; David Jordan, Member