The application of fertilizers and saline irrigation water have resulted in increased soil salinity and the removal of large land areas from crop production. One method to overcome the effects of soil salinity is to increase the salt tolerance of crops. The objective of this research was to investigate the physiological, genetic, and agronomic differences between alfalfa (Medicago sativa, L.) bred for increased salt tolerance and salt sensitive alfalfa. The materials used in these studies were the result of five cycles of selection for germination NaCl tolerance, AZST 1978 to 1982, and the source population, 'Mesa-Sirsa'. All salt-tolerant cycles and Mesa-Sirsa were evaluated for ability to germinate in NaCl, NaNO₃, KCl, KNO₃, mannitol and polyethyleneglycol (PEG) solutions ranging from -1.0 to -1.6 MPa of osmotic potential and a control of distilled water. Germination in the lower osmotic potentials of all germination medias was significantly higher with each succeeding cycle of selection for germination NaCl tolerance. Selection for tolerance to NaCl during germination also resulted in increased tolerance to the other salts as well as mannitol and PEG. Germination in mannitol was higher than in any of the salt solutions. This suggests that ion toxicity also inhibits germination. There was no significant difference between Mesa-Sirsa and AZST 1982, the most salt-tolerant cycle, in seed respiration in NaCl solutions or in uptake of tritiated NaCl solution during germination. Broadsense heritability of germination NaCl tolerance was estimated at 49%. All the Arizona Salt Tolerant cycles and Mesa-Sirsa were evaluated for several mature plant characteristics under non-saline field conditions. There were no significant differences among germplasm sources in forage yield, apparent photosynthesis, transpiration, or diffusive resistance. Seedlings of Mesa-Sirsa and AZST 1982 were grown in NaCl solutions ranging from 0 to 18000 ppm NaCl in the greenhouse. The plants were evaluated for several plant growth characteristics to determine whether selection for germination NaCl tolerance resulted in increased salt tolerance at more mature plant growth stages. There was no evidence that germination salt tolerance is related to salt tolerance at later growth stages in alfalfa. Salt tolerance during germination and later growth stages may be controlled by different physiological and genetic mechanisms.

A series of studies in mice were performed to determine the interaction of two sulfur nucleophiles, oral n-acetylcysteine (NAC) and intravenous sodium thiosulfate (Na₂S₂O₃) with the anticancer drug mitomycin C (MMC). Neither nucleophile reduced MMC lethality or hematopoietic toxicity. Both increased the antitumor activity of MMC in mice bearing P-388 and L-1210 leukemias. There was no nucleophile reduction of MMC effects on normal bone marrow stem cells (CFUs) using a murine spleen colony forming assay. In contrast, the nucleophiles significantly enhanced MMC bone marrow toxicity. Three clonogenic human tumor cell lines (HEC-1A endometrial, 8226 myeloma, WiDr colon) were relatively resistant to MMC and the nucleophiles did not increase activity. A human breast cancer cell line (MCF-7) was sensitive to MMC and this activity was blocked by glutathione. Oxygen free radical scavengers did not reduce MMC activity. A novel isocratic high performance liquid chromatography (HPLC) assay (48:52, methanol:0.01M phosphate buffer) using ultraviolet detection at 365 nm was used to characterize MMC-protein binding and murine pharmacokinetics. The k' for MMC was 7.91 and 9.86 for porfiromycin. Peaks were confirmed by mass spectroscopy. MMC was bound 30% to albumin and S-9 microsomal proteins and 60-70% to calf thymus DNA. MMC uptake into mouse bone marrow was enhanced by the nucleophiles and was rapidly cleared from the plasma (half-life 0.5 hours). In vitro MMC metabolism with rat liver S-9 microsomes demonstrated production of a polar eluting, putative MMC metabolite (K' = 4.486, lambda maximum 300 nm). This metabolite was inactive in the in vitro clonogenic tumor cell assay. Finally, molecular pharmacology studies using alkaline DNA elution showed that MMC causes both DNA-DNA and DNA-protein crosslinks. There was no evidence for free radical-induced DNA strand scission by MMC. There was also some evidence of moderate DNA protection with the sulfur nucleophiles.

An investigation into the flux of soil water under the influence of a thermal gradient was conducted in closed soil systems in the laboratory. A thermal gradient was imposed across the sandy loam soil columns and measured continuously for the duration of the experiment. The movement of soil water was monitored periodically using a gamna ray attenuation device until the columns reached an apparent steady state condition with no net flow. Imposition of boundary conditions enabled delineation and evaluation of the system parameters. Values of net water flux in soil columns were analyzed using the Taylor-Cary irreversible thermodynamic and the Philip-de Vries theory of water movement. Application of the Taylor-Cary equation to describe the flow reveals that for initial time periods the flow is slightly overestimated, however, this small difference may be within the realm of experimental error. The flow predicted by the Taylor-Cary equation for the succeeding time periods greatly exceeded the measured flow rates. The Philip-de Vries theory of soil-water movement predicted greater net water movement than was observed in soil columns with a temperature gradient of 2.67 ° C/cm and with an average soil water content of 10.5 to 11.5 cm³/cm³. The following conclusions were reached after analyzing the data for the sandy loam soil material. Water content and temperature influence the diffusion transfer coefficient, β*, in a closed soil system. Thus the transfer coefficient is not an independent entity. Hysteresis is present in the wetter part of the system, although the magnitude of hysteresis involved is unknown. The β* coefficient can be evaluated only in regions where hysteresis is not present. The transfer of soil water was greater in a leached soil with no air gap than in an unleached soil with no air gap. There was supporting evidence that liquid water continuity did not exist throughout the column since there was no appreciable solute transport. The observed change in soil water content distribution at 18.0 cm³/cm³ to the imposed temperature gradient was not significant for the sandy loam soil material. The observed soil water flux increased in response to the imposed temperature gradient as soil water content decreased from 18.0 to 10.5 cm³/cm³. No analytical procedure is presently available that will describe thermally induced flow under all conditions. The approach of Philip and de Vries requires that the physical properties of the soil must be known accurately so that correct estimates can be made of the individual diffusivities. This approach has been found to predict the flow with some success on relatively dry soils, however, it possibly would be in error when estimating thermally induced flow in regions where liquid continuity exists and up through to a saturated system. The Taylor and Cary equation may be adequate for describing water flow to predict trends or obtain comparative values, however, much additional work needs to be done before it will adequately describe the flow for transient conditions or steady state conditions where nonuniform water content distributions are present.

This item was digitized as part of the Million Books Project led by Carnegie Mellon University and supported by grants from the National Science Foundation (NSF). Cornell University coordinated the participation of land-grant and agricultural libraries in providing historical agricultural information for the digitization project; the University of Arizona Libraries, the College of Agriculture and Life Sciences, and the Office of Arid Lands Studies collaborated in the selection and provision of material for the digitization project.

The purpose of this dissertation is to investigate the extent to which there is consistent evidence pertaining to the prime lexicality effect. Theoretical claims about the nature of this effect, in which masked nonword form primes produce greater facilitation than word form primes, have been hotly debated in the masked priming literature. Here, there are two major conflicting accounts of visual word recognition to consider. Cascaded activation approaches such as the Interactive Activation model rely on competition between word units to account for word recognition. This view predicts inhibitory effects for word form primes due to competition between word units for the prime and target. In contrast, proponents of the Search Model have maintained that elements in the process of verifying visual input suggest that word primes should produce neither facilitatory nor inhibitory effects during masked presentation. Evidence that is consistent with both approaches has been reported in the literature. A 1998 study by Forster and Veres looked at long words using a masked lexical decision task and demonstrated strong facilitation from nonword primes and no effect for word primes. A 2006 paper for Davis and Lupker, however, reported that the nonword prime facilitation that they observed using the same task was accompanied by strong word prime inhibition. The presence of this inhibitory effect seems to support the interactive activation account, but it remains unclear why inhibitory effects such as these were not seen in the Forster and Veres work. The present study sought to explore the reliability of the effects that are generated by word form primes. In particular, the different types of stimuli used in the conflicting papers (i.e. long versus short items) were contrasted. Evaluations regarding their relative discrimination difficulty and performance during masked lexical decision were conducted. The investigation revealed that there is indeed a difference between the output provided by those different stimulus types and that context effects emerge when they are presented together in the same experiment. The implications of these findings for the various views on visual word recognition are discussed.

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