Yield, crude protein, and crude fiber of 'Piper' sudangrass (Sorghum bicolor var. sudanese (L.) Moench), and 'Sweet Sioux' and 'FFR66 1 sorghum (Sorghum bicolor(L.) Moench) X sudangrass hybrids were studied during the growing season and after frost. Three treatments were studied, namely--4-s (four summer harvests and short or about 0.6 m at the time of frost), 3-M (three summer harvests and medium or 1.5 in at the time of frost), 2-T (two summer harvests and tall or 2.0 in at the time of frost). Dry matter yield, crude protein, and crude fiber were calculated. The three cultivars did not differ consistently for yield, crude protein, or crude fiber during the summer or fall. The 3-M treatment provided more dry matter (not significantly higher than the 2-T treatment), more total crude protein, and approximately the same amount of crude fiber as the 4-S and the 2-T treatment. Results of this study indicate that sorghum cultivars can be grazed rotationally, or cut for hay or silage during early summer, and the late summer and early fall growth accumulated for in situ utilization by livestock during fall and early winter.

This investigation represents one of the first electron microscopic studies on determining the mode of action of the chemical herbicide sethoxydim, 2-[-1-(ethoxydimino)butyl] -5-.2-(ethiothio)propyl]-3- hydroxy-2-cyclohexen-1-one. Samples were excised from the intercalary meristem of johnsongrass (Sorghum halpense) at time intervals of 1,3, 6,12,24,36,48,60, and 72 hours and examined using electron microscopy. Transmission electron micrographs revealed that cellular activity shows alterations or abnormalities as early as six hours. Membranes show deterioration at this time and chloroplasts contain densely staining starch granules. As time intervals increase, cellular degradation becomes more evident. Nuclear membranes extend outward into the cytoplasm in various types of cells. After 72 hours, the protoplasm demonstrates plasmolysis. The cell walls, plasma membranes, and plasmodesmata are also influenced by the sethoxydim treatment. Scanning electron micrographs were studied for the effects on vascular bundles and the surrounding tissue. The results were similar to those found by transmission electron miscroscopy.

Topoisomerases are enzymes of critical biological significance. Despite this fact, little data specific to the topoisomerases of higher plants has been published. This research was undertaken to isolate and characterize a higher plant topoisomerase from soybean hypocotyls to further the understanding of the structure and function of these enzymes. Nuclei were isolated from frozen hypocotyls of 4 day old etiolated soybeans by homogenization and centrifugation, then lysed by gentle stirring in the presence of 1.5 mM ammonium sulfate. The resultant extract was desalted and purified by column chromatography on DEAF sepharose, 5-200 sephacryl and CM cellulose. The components of the purified fraction were separated by electrophoresis on non-denaturing polyacrylamide and recovered by electro-elution. The molecular weight of the native enzyme was determined to be 225 kilodaltons (Kd) by gel filtration and 300 Kd by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Three smaller molecular sub-species, possibly resulting from dissociation of the native enzyme in the presence of beta mercaptoethanol (BME), were isolated. These smaller molecules had approximate molecular weights of 155 Kd, 29 Kd and 25 Kd. The two smaller polypeptides appeared to re-associate to form a 68 Kd aggregate in the absence of BME. This aggregate was subsequently resistant to denaturation by sodium dodecyl sulfate (SDS). The purified native enzyme was found to be adenosine triphosphate (ATP) and Mg++ (divalent magnesium ion) independent. Although not required, the presence of magnesium (Mg) stimulated enzyme activity. Manganese (Mn++) stimulated activity to a lesser degree. Enzymatic activity was inhibited by ATP, potassium chloride (KC1) and N-ethylmaleimide (NEM) but not inhibited by novobiocin. The results indicate that a type I topoisomerase was purified from the nuclei of soybeans (Glycine max). The soybean topoisomerase I has a native molecular weight similar to that of cauliflower (200 Kd) and like cauliflower topoisomerase was inhibited by NEM but not by novobiocin and was stimulated by Mg++. It is similar to vaccinia virus topoisomerase I in being slightly inhibited by ATP. The data suggests that the native enzyme may be composed of enzymatically active domains as small as 27 Kd and thus is similar to vaccinia virus and Ustilaqo maydis topoisomerase I.

The effect of black polyethylene mulching and drip irrigation on the yield and quality of three cultivars of bell pepper was studied during the 1987 growing season. This study was conducted on a Pembroke silt loam soil on the Western Kentucky University Farm in Bowling Green, Kentucky. The experimental design was a split-plot arranged in randomized complete blocks in four replications with treatment as the main plot and cultivars as the sub-plot. 'California Wonder,' 'Lady Bell F1 Hybrid: and' Keystone Resistant Giant' cultivars of bell pepper were established in the field during the last week of May. The cultivars were grown using black polyethylene, with application of irrigation (no mulch) and without irrigation or mulch (check) Irrigation was initiated in early August and continued throughout the remainder of the growing season; the amount per application was 158.8 m3/ha. At harvest, mature green fruit were removed from the plant, weighed, and classified as grade I or II. There were significant differences at the 5% level in the yield of the cultivars. There were significant differences at the 5% levels among the yields of the treatments. the higher yield was obtained with irrigation, followed by the use of mulch. The better yield under each of the three treatments was obtained with the cultivar Lady Bell. The production of grade II peppers Was higher than the production of grade I peppers, the average yield was 48.82 MT/ha, and 21.99 MT/ha, respectively. The yield of bell pepper grade II was higher in all three treatments.

The effects of within-row spacings and cultivars on the yield of bush snap beans (Phaseolus vulgaris L.) were studied in two experiments. In each experiment, two cultivars and four within-row spacings (8, 15, 23 and 30 cm) were arranged in a split-plot with four replications. Spacing treatments were the whole plots and cultivars were the split plots. In 1988, the two cultivars were 'Blue Lake 274' and 'White Half Runner'. In 1989, the cultivars were 'Blue Lake 274' and 'Kentucky Wonder 125'. All rows were spaced 91 cm apart. Pods were harvested and oven dried. The data were subjected to analysis of vlriance procedure for a split-plot design, assuming a fixed model. In 1988, White Half Runner was significantly higher yielding than Blue Lake 274. In 1989, yield of Kentucky Wonder 125 was significantly greater than that of Blue Lake 274. Bean yields were significantly influenced by spacing treatments in 1988 and 1989. Yields per plant were significantly higher for the 30-cm than for the 15- and 8-cm spacings. Yields for the 23-cm spacing treatment were significantly higher than those for the 8-cm treatment. Yields per meter of row showed no significant differences at any spacings. The linear effect for spacings was significant for both yield per meter of row and yield per plant in 1988 and 1989.

Four experiments regarding water relations to germination of zea mays. Per cent of water absorbed by seeds of zea mays with supply of water controlled and filter paper used as water absorbent. Per cent of water absorbed by seeds of zea mays with supply of water controlled and filter paper used as water absorbent. Per cent of water absorbed by seeds of zea mays with supply of water controlled and cotton used as water absorbent. Per cent of water absorbed by seeds of zea mays with supply of water controlled and cotton used as water absorbent.

Breeding herbicide-tolerant cultivars is a means of extending herbicide utilization. In 1983 and 1984, 20 soybean [Glycine max (L. Merr] cultivars were screened for their reactions to the following herbicides: metribuzin 4-amino-6-(tert)-butyl-3-(methylthio)-astriazin-5-(4H)-one]; vernolate (S-propyl dipropylthiocarbamate); and fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl) aniline]. Each herbicide was applied at the recommended rate X, 2X, and 4X in 1983. An 8X rate was added in 1984. The recommended rates (X) for the herbicides were as follows: metribuzin 0.42, vernolate 2.80, and fluchloralin 1.12 kg/ha. The cultivars were Pella, Pixie, Cumberland, Williams, Essex, Union, Semmes, Tracy, Tracy M; North American Plant Breeders 350, 68225, 420, and 330; Northrup King 8069 and 8047; and Farmers Forage Research 339, 340, 560, and 561. Plant vigor, height, and herbicide injury were the criteria used in estimating herbicide effects. Statistical differences were found among herbicides, rates, and cultivars. Also, there were significant interactions involving herbicides x rates, herbicides x cultivars, rates x cultivars, and herbicides x rates x cultivars. Although not always statistically significant, average vigor ratings decreased with increased herbicide application rate. Pronounced differences in the study results for the two years, likely reflecting rainfall patterns, were evidence of uncontrolled variability. However, a small number of the cultivars exhibited herbicide tolerance.

Arsenic (As) is a toxic semi-metallic element found in groundwater, soils, and plants. Natural and anthropogenic sources contribute to the distribution of arsenic in the environment. Arsenic’s toxic and mobile behavior is associated with its speciation ability. There are two types of arsenic available to the environment, inorganic and organic arsenic. Of the two, inorganic arsenic is more toxic to humans and more mobile in the environment. Two inorganic compounds responsible for arsenic contamination are trivalent arsenite, As (III), and pentavalent arsenate, As (V). Trivalent arsenate is considered to be more soluble, toxic, and mobile than pentavalent arsenate. Arsenic’s absorptive properties in plant cells and ability to attach to minerals causing secondary contamination are due to environmental factors such as pH, redox potential, and solubility. The current maximum contaminant level for arsenic in water is 10 µg/L (or ppb). Research on arsenic involving high concentrations already present in groundwater (>300ppb) are compared either with crops irrigated with such water or a human indicator (such as; hair, nails, blood, or urine) in order to determine exposure limits. In this current research, relationships between the area in the studies and the contaminated media (water, soil, vegetation) were tested to determine if arsenic in water was correlated with arsenic concentrations present in soil and vegetation. Commercially obtained ITS Quick Rapid Arsenic Test Kits were used to measure arsenic concentrations for the media tested. A method for analysis of arsenic in vegetation was developed, with an estimated 80% recovery. The pH and conductivity were also taken for water and soil samples as a means of correlative comparison. The development of faster and portable methods for arsenic concentration may provide means for predicting the relationship between all contaminated media. The purpose of the study was to determine the correlation between arsenic water concentration and pH for water, soil, or vegetation and whether it plays an overall role in the amount of arsenic present. As a result, water and soil pH played a significant role in the presence of arsenic in the water and vegetation, respectively. A moderate negative correlation between arsenic in water and water pH was discovered to have a Spearman’s rho value of -0.708 with a p ≤ 0.05. In addition, a significant negative correlation between soil pH and arsenic in vegetation was also discovered to have a Spearman’s rho of -0.628 at a p ≤ 0.05. Even though, pH was significantly correlated with arsenic concentrations in different media, there is evidence that pH plays a role also in the amount of arsenic available in the soil and vegetation. Further studies are recommended.

This study addressed the effects of salinity and pot size on the interaction between leguminous plant hosts and arbuscular mycorrhizal fungi in four pine rockland soils using a shade house trap-plant experiment. Little is known about the belowground diversity of pine rocklands and the interactions between aboveground and belowground biota – an increased understanding of these interactions could lead to improved land management decisions, conservation and restoration efforts. Following twelve weeks of growth, plants were measured for root and shoot dry biomass and percent colonization by arbuscular mycorrhizal fungi. Overall, arbuscular mycorrhizal fungi had positive fitness effects on the four legume species (Cajanus cajan, Chamaecrista fasciculata, Tephrosia angustissima and Abrus precatorius), improving their growth rate, shoot and root biomass; pot size influenced plant-fungal interactions; and percent colonization by arbuscular mycorrhizal fungi was influenced by soil type as well as salinity.

Owing to their increasing application and potential toxicity, engineered nanoparticles (ENPs) have been considered as a potential agricultural contaminant that may pose unknown risk to human beings. However, many techniques require invasive and complicated sample preparation procedures to detect and characterize engineered nanomaterials in complex matrices. In the first part of this thesis, we present a non-destructive and label-free approach based on surface enhanced Raman spectroscopic (SERS) mapping technique to qualitatively detect and characterize gold nanoparticles (AuNPs), on and in spinach leaves in situ. We were able to detect the clearly enhanced signals from AuNPs at 15 to 125 nm on and in spinach leaves. Peak characterizations revealed the aggregation status of Au NPs and their interactions with plant biomolecules, such as chlorophylls and carotenoids. This developed approach will open a new analytical platform for various researches on studying ENPs' adhesion and accumulation. The second part focuses on investigating the interaction between AgNPs and plant leaves using surface enhanced Raman spectroscopy. AgNPs of different surface coating (citrate, CIT and polyvinylpyrrolidone, PVP) and size (40 and 100 nm), were deposited onto spinach leaves. SERS signals produced from all kinds of AgNPs exhibited a unique C-S stretching peak at 650-680 cm-1. In vitro study indicates this peak may originate from the interaction between AgNPs and cysteine-like compounds based on the peak pattern recognition. The interaction between AgNPs and the cysteine-like compounds happened as soon as 0.5 h after AgNPs exposure. The in situ replacement of the CIT with the cysteine-like compounds on the AgNP surfaces was faster compared to that of the PVP. Based on the mapping of the highest C-S peak, we observed the CIT-AgNPs penetrated faster in spinach leaves than the PVP-AgNPs, although the penetration profile for both of them is similar after 48 h (P ˂ 0.05). The 40 nm CIT-AgNPs was able to penetrate deeper (to the depth of 183 ± 38 µm) than the 100 nm CIT-AgNPs (to the depth of 90 ± 51 µm) after 48 h. The results obtained here demonstrate the size of AgNPs is the main factor that affects the penetration depth, and the surface coating mainly affects the initial speed of interaction and penetration. This study helps us to better understand the distribution and biotransformation of AgNPs in plants. In the third part, the removal efficiency of postharvest washing on AgNPs that had accumulated on fresh produce was evaluated. Ten µL commercially available 40 nm citrate coated AgNPs (0.4 mg L-1) were dropped to a (1×1 cm2) spot on spinach leaves, followed by washing with deionized water (DI water), Tsunami® 100 (80 mg L-1) or Clorox® bleach (200 mg L-1). Then, AgNPs removal efficiency of the three treatments was evaluated by surface enhanced Raman spectroscopy (SERS), scanning electron microscopy (SEM)-energy dispersive spectrometer (EDS), and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS results showed that deionized water removed statistically insignificant amounts of total Ag, whereas Tsunami® 100 and Clorox® bleach yielded 21% and 10% decreases in total Ag, respectively (P < 0.05). The increased removal efficiency resulted from Ag NPs dissolution and Ag+ release upon contact with the oxidizing agents in Tsunami® 100 (peroxyacetic acid, hydrogen peroxide) and Clorox® bleach (sodium hypochlorite). According to the SERS results, the deionized water and Tsunami® 100 treatments removed nonsignificant amounts of AgNPs. Clorox® bleach decreased Ag NPs by more than 90% (P < 0.05), however, SEM-EDS images revealed the formation of large silver chloride (AgCl) crystals (162 ± 51 nm) on the leaf, which explained low total Ag removal from ICP-MS. This study indicates current factory washing methods for fresh produce may not be effective in reducing AgNPs (by water and Tsunami® 100) and total Ag (by all three means). This highlights the necessity to develop an efficient washing method for NP removal from food surfaces in the future.