Tobacco (<i>Nicotiana tabacum</i> 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.

The Fourier Transform Infrared spectrometer (FTIR) has been used increasingly as a detector for various forms of chromatography. Clearly the most established marriage has been that of the Gas Chromatograph (GC) with the FTIR. GC-FTIR has been developed well beyond other forms. The main objective of this thesis, however, is to extend the FTIR as a detector to previously untested forms of chromatography using a flow cell interface. These forms of chromatography include High Performance Liquid Chromatography (HPLC), both normal-phase and reversed-phase, and packed-column Supercritical Fluid Chromatography (SFC). Normal phase HPLC-FTIR was demonstrated on not only analytical scale columns, but semi-preparative and microbore scales as well. Significant advantages, particularly with respect to the low solvent consumption, were found in the microbore HPLC-FTIR experiment. This led to the development of a chromatographically improved flow cell, the Zero Dead Volume (ZDV) HPLC-FTIR interface. The ZDV cell shows superior chromatographic characteristics and has unique spectrometric characteristics because of its unusual cross-section. Detection limits as low as 40 ng were observed. Extension to reversed-phase HPLC-FTIR required incorporation of the Flow Injection Analysis (FIA) technique of low-dispersion flowing extraction. The compounds separated by HPLC are extracted into an infrared-transparent solvent, and the extracted compounds are detected by similar means to normal-phase HPLC-FTIR. Investigation of SFC-FTIR incorporated a high-pressure, gold-lined lightpipe flow cell to detect the components separated by the supercritical C0₂/packed-column chromatograph. Several unusual spectrometric characteristics were noted. Detection limits as low as 50 ng were observed with SFC-FTIR. / Ph. D.

Forage crops grown in many parts of the Appalachian region are restricted in yields as a consequence of shallow soils, low levels of essential nutrients, toxic levels of aluminum, and low pH. Therefore, the successful growth of alfalfa in these regions is dependent on either changing existing edaphic conditions or modifying the plant physiologically so as to improve nutrient acquisition and utilization. The purpose of the present study was to determine if chemicals reported to possess growth regulatory properties affect nutrient uptake and utilization and how such effects are manifested in the plant. In the first series of experiments, foliar sprays containing 10 mM CaCl₂ with or without tetracosanoic acid (C-24), hexacosanoic acid (C-26), triacontanoic acid (C-30), or dipalmitoyl phosphatidic acid (DPA) were ineffective (p=0.05) in enhancing alfalfa (Medicago sativa, Arc) shoot or root biomass when applied to 21 and 28 day-old plants. DPA treatments also had no effect (p=0.05) on the leakage of Ca²⁺, K⁺, Mg²⁺, and PO₄³⁻ from foliar leaf discs. Foliar treatments containing either 10 mM CaCl₂ + DPA or 10 mM CaC1₂ were effective in increasing shoot biomass in plants grown in solution culture containing suboptimal levels of calcium and phosphate. The increased biomass, however, was attributed to calcium supplementation rather than the effect due to DPA. The second series of experiments evaluated the effect of seed treatments with the growth retardant XE-1019 ((p-chlorophenyl)-4,4-dimethyl-2(1,2.4-triazol-1-yl)-1-penten-3-ol) on alfalfa growth, chlorophyll concentration, ionic leakage, nutrient uptake, and root nodulation. Seed treatments resulted in plants with significantly reduced (p=0.05) shoot and root biomass and thicker greener leaves. Quantitation of leaf chlorophyll indicated that the seed treatments caused significant increases (p=0.05) in both chlorophyll a and b concentrations at initial growth stages. After six weeks, no significant differences in chlorophyll concentrations were detected. XE-1019 had no apparent effect on leaf membrane permeability or transport since no significant differences (p=0.05) were detected in the leakage of Ca²⁺, K⁺, Mg²⁺, and PO₄³⁻ from foliar leaf discs. However, whole plants treated with XE-1019 depleted significantly (p=0.05) higher amounts Ca²⁺, K⁺, Mg²⁺, and PO₄³⁻ from hydroponic solutions on a per centimeter root basis. On a per plant basis, untreated plants absorbed greater quantities of the assayed nutrients. The presence of XE-1019 in the rhizosphere was not deleterious (p=0.05) to the inoculation of the root with Rhizobium meliloti and the subsequent formation of root nodules. Seed treatments with XE-1019 also had no effect on the cultured growth of Rhizobium meliloti strains 102F34a, l02F51a, 102F66d, and 102F77b. / Master of Science

Call number: LD2668 .T4 1953 W48 / Master of Science

Call number: LD2668 .T4 1957 F75 / Master of Science

Call number: LD2668 .T4 1958 M17

Call number: LD2668 .T4 1963 P37 / Master of Science

Call number: LD2668 .T4 1964 M11 / Master of Science

Call number: LD2668 .T4 1978 A51 / Master of Science

Call number: LD2668 .T4 1978 S31 / Master of Science