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.

Research was undertaken in the summer and fall of 1988 to determine the effect of phosphorus placed below, below and to the side, banded and incorporated, and broadcast on the yield and quality of tomatoes. The results of the field study were not statistically significant due to high levels of available soil phosphorus. However, there were trends toward higher total yields, higher yield of number one grade tomatoes, and higher tissue phosphorus levels when phosphorus was placed in a concentrated zone or band as contrasted with the more popular broadcast method. The effect of phosphorus placement in the greenhouse was studied using two different soils, a high available phosphorus soil and a low available phosphorus soil. Again, phosphorus placed in a concentrated zone produced plants with higher tissue phosphorus levels, regardless of the soil the plants were grown on.

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.

The effects of ensiling on HCN potential (HCN-p) of sorghum plants were studied at Bowling Green, Kentucky in 1969-70. Four cultivars were sampled at various growth stages and ensiled in 1.8 liter glass containers fitted with gas release valves. The plant material was analyzed for HCN-p by the sodium picrate procedure prior to ensiling, immediately after being removed from the silo, and after 24 and 48 hours of air-drying. Gases released during ensiling, and gases flushed from the silos were analyzed for HCN. The level of HCN-p decreased during the ensiling period and during the first 24-hour drying period. Some HON was found in the gases which were released during the aerobic respiration portion of the ensiling process. Low levels Of HCN were detected when the silos were flushed with CO2 at intervals during the ensiling period. Although the levels of HCN-p varied with cultivars and growth stages, the ensiling effects were relatively consistent for cultivars and growth stages.

The short term effects of high manganese levels (80 mg/L) on wheat and tobacco isocitrate dehydrogenase (IDH) activity were compared. The change in activity was then compared to the concentrations of manganese in the tissues. As the time of manganese exposure increased, the fresh weight IDH activities in wheat and tobacco decreased. In contrast both control groups had similar enzyme activities every 6 hr over the 24 hr test period. The decrease in IDH activity of wheat and tobacco plants in experimental groups seemed to be related to an increase of the manganese in the leaf tissue. The slower decrease in the IDH activity of wheat and the faster decrease in the IDH activity of tobacco appeared to correspond to manganese levels in the respective tissues. It appears that wheat is able to tolerate the higher manganese concentration in the growth media better than tobacco.

No-tillage production of crops has developed and become widespread since the late 1950/s. No-till is dependent upon the use of broad spectrum herbicides to kill weeds already growing at planting time. Until recently, this has almost exclusively been paraquat (1,1'-dimethy1-4,4'-bipyridinium ion). Glyphosate [N-(phosphonomethyl)glycine] is a new herbicide which has great potential for use in no -tillage production. Soybeans (Glycine max L.) were planted in the stubble after wheat (Triticum aestivum L.) was harvested. All plots received applications of the residual herbicides alachlor [2-chioro-2',6'-diethyl-N-(methoxymethyl)acetanilide] and linuron [3-(3,4-dichlorophenv1)-1-methoxy-1-methylurea]. Each plot also received either paraquat or glyphosate or was designated as a check. Glyphosate was appiied at three different volumes and paraquat at only one volume. All mixtures were applied at two spraying pressures. Applications were made to areas where straw was undisturbed after combining and to areas where the straw had been removed. Ratings taken 10 days and six weeks after herbicide application indicate that glyphosate performs as well as or better than paraquat. The ratings also indicate that glyphosate performs as well at 187 L/ha as it does at 574 L/ha. Spraying pressure and removal of straw seem to have little effect on the degree of weed control.

The lack of adequate weed control is one of the major problems encountered in soybean production. Johnsongrass presents one of the most serious weed control problems in the Southeastern United States. numerous herbicides are used in an effort to control johnsongrass, and research is still being conducted to find new herbicides for this purpose. Two of these herbicides are BAS 9021 [6,6-dimethyl-2,4-dioxo- 3[1-[2-(propenyloxy)amino]butylidene]-cyclohexane] and BAS 9052 [2-(n-ethoxybutyrimidoyl)-5-(2-ethylthiopropy1)-3- hydroxy-2-cyclohexen-1-one]. In 1978, johnsongrass control with BAS 9021 at 1.1 and 1.7 kg/ha in sim-le early postemergence or late postemergence applications, or in each of two split applications, was evaluated using the herbicide alone, with a nonionic surfactant, or a nonphytotoxic crop oil. The split applications gave johnsongrass control ranging from 49, to 81,. Late postemergence applications of 1.7 kg/ha of BAS 9021 were as Food as split applications. As a group, the addition of oil or surfactant gave increased control over the herbicide alone. In 1979 BAS 9021 and BAS 9052 were compared with mefluidide [N-[2,4-dimethyl-5[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide]and alachlor (2-chloro-2'6'-diethyl-N-(methoxymethyl)acetamide] for seedling johnsongrass control. The BAS materials were compared with mefluidide, trifluralin]α, α, α trifluoro-2,6-dinitro-N,N-dipropyl-p-toliuidine], fluchloralin [N-(2-chloroethyl)-2,6-dinitro-n-propyl- 4-(trifluoromethyl)aniline] and trifluralin plus vernolate [S-propyl dipropylthiccarbamate] for rhizomic johnsongrass control. In both experiments BAS 9021 was applied at 1.1 and 1.7 kg/ha in each of two applications. BAS 9052 was applied at rates of 0.6 to 1.1 kg/ha early postemergence, late postemergence or in split applications. Mefluidide was applied at rates of 0.3 to 0.6 kg/ha either early postemergence or in split applications. All postemergence herbicide applications contained an oil concentrate at a rate of 2.4 L/ha. Alachlor for seedling control was applied preemergence at 3.4 and 4.5 kg/ha. Preplant incorporated applications of trifluralln and fluchloralin were made at rates of 2.2 kg/ha and vernolate at 2.8 kg/ha was combined with —1 and 2.2 kg/ha of trifluraiin for rhizomic johnsongrass control. In the seedling area, all BAS treatments gave 88% or better johnsongrass control. In the rhizomic area split applications of BAS 9052 tended to result in the best johnsongrass control. Ratings were taken both 8 and 11 weeks after planting. Soybean yields were generally better with higher johnsongrass control. Mefluidide caused apparent soybean injury, resulted in poor johnsongrass control and lowered soybean yields. All preplant incorporated treatments gave poor johnsongrass control and low soybean yields. Alachlor gave fair johnsongrass control but resulted in high soybean yields.

The effect of three tillage methods confounded with three row widths on root length and depth, seed density, seeds per pod, pods per plant and yield of Glycine max was studied during the 1984 growing season. The study was conducted on class 1, Pembroke soil located in south Warren County, Kentucky. A barley crop was removed from the area just prior to the experimental plantings. A John Deere conservation tillage, plateless planter was used in all experimental treatments except the drilled plots. Plant populations were adjusted to conform to standard recommendations for drill (7 inch row widths), 15-inch row widths, and 30-inch row widths. Tillage methods were no-till (soybeans were seeded directly into barley stubble), conventional (the land was chisel plowed to a depth of 8 to 10 inches and then disced twice to a depth of four inches prior to planting), and ro-till (the ro-till machine prepared a 10 inch wide seed bed directly into barley stubble by utilizing a deep chisel preset to reach a depth of ten inches, four large disks preset to run at a depth of approximately six inches followed by a rolling steel basket designed to level the seed bed and macerate large particles of soil). All experimental plots were planted within a six hour time span. The eight row width by tillage method treatments were fifteen inch no-till (15N), thirty inch no-till (30N), fifteen inch conventional (15C), thirty inch conventional (30N), fifteen inch ro-till (15R), thirty inch ro-till (30R), drill conventional (DC), and drill ro-till (DR). Treatments were arranged in a randomized complete block design replicated six times. Each block contained all treatments arranged in a random fashion to reduce error due to side-row variation. Root length and depth determinations were made at the crook, unifoliate, first trifoliate, third trifoliate, and fifth trifoliate stages of development. Seed density, seeds per pod, pods per plant, and yield were studied at physiological maturity. Rainfall was recorded daily throughout the growing season. Results showed significant differences in root length, root depth, seed density, and yield; but no significant differences were found in seeds per pod or pods per plant. The ro-till tillage method improved root development (depth and length) over the conventional and no-till tillage method; however, yield data was not greatly affected by this improvement. Yield was seemingly affected most by row-width differences with drilled rows and 15-inch rows ranking above 30-inch rows in production.