'Golden Delicious' winter squash (GDWS), Cucurbita maxima Duchesne, provides significant amounts of pollen (24 mg) and nectar (236 μl), but with a low reward of 14% nectar sugar. The quantity of nectar produced per GDWS flower differed between sites and floral sex. The GDWS male flowers had 25% higher sugar concentration than female flowers. There was no statistical difference in the percent of nectar sugars per flower between sites, but the interaction between site and floral sex was statistically significant for the amount of nectar and percent of nectar sugars. Pollen production per flower differed significantly between sites with the most productive site producing 27% more, and 45% more than the other sites. Pollination efficiency of honeybees and bumble bees was assessed with field cages (1.8x1.8x1.8 m). No significant differences were found except for the interaction between the bee treatment and year on number of fruit per cage. This significant difference reflects the increase in fruit number produced by honey bees in 1997. The effect of distance from honey bee hives on fruit and seed quality was tested, and found significant only for B- and C-seeds weight, which were both less in the plots farthest from the nearest group of honey bee hives. Placement of honey bee hives in fields of ≤120 ha appears not to be critical for adequate pollination of GDWS. Other pollinators (excluding honey bees) were frequent visitors to the squash flowers studied here - for example, Bombus spp., Megachilids, Halictids, etc. These other pollinators, mostly bumble bees, accounted for 3.55% of all bee visits. Honey bees visited proportionately more female flowers in the morning, and progressively switched to the more abundant male flowers in the afternoon. This bias differed by site and year. Bumble bees visited proportionally slightly more male GDWS flowers than did female flowers and did it in a similar rate throughout the day. From 15 minute observations each hour of individual female GDWS flower, we calculated that they received approximately 80 honey bee visits per day. / Graduation date: 2001

Volcanic tuffs and tuffaceous sediments are frequently associated with elevated As groundwater concentrations even though their bulk As contents (~ 5 mg kg-1; Savoie, 2013) are only marginally greater than the average crustal abundance of 4.8 mg g-1 (Rudnick & Gao, 2003). Thus, As mobilization must be facilitated by conditions particular to these rocks. Alkaline desorption, anionic competition, reactive glass dissolution, and reductive dissolution of iron oxides are proposed processes of As release from volcanic rocks. Geogenic As contamination of groundwater in the southern Willamette Valley in western Oregon has been well-documented since the early 1960s, and previous studies have identified the Little Butte Volcanics Series and Fisher and Eugene Formations as the source of As contamination. This study examines 19 samples from 10 units of ash flow tuffs and tuffaceous sediments within the Fisher Formation and Little Butte Volcanics Series, representing a range of weathering and devitrification, to determine conditions of mobilization and mineralogical constraints that control As release into solution. Leachate studies were conducted over a range of pH from 7 to 11, phosphate concentrations from 10 μM to 100 mM, and in time series from 4 to 196 hours. Results demonstrate that silicic volcanic tuffs are capable of mobilizing As in concentrations above regulatory limits at pH conditions produced naturally by the tuffs (pH 8-9) or with moderate concentrations of P (10-100 μM). Alteration products, e.g. zeolites and clays, appear to be the primary host phases for mobile As. Samples that do not contain these alteration products tend to produce concentrations of As well below regulatory limits and often below the instrument detection limits of this study. The type of alteration may influence As mobilization: tuffs containing more clays tend to mobilize As through surficial desorption, and tuffs containing more zeolites tend to mobilize As by dissolution or formation of colloids. Additionally, one volcaniclastic sample demonstrates that extremely elevated concentrations of As, up to 1000 μg/L are possible as a result of oxidative dissolution of As-bearing sulfide phases.

Over 115 miles of rock revetments that serve to protect river banks have been constructed in the Willamette Basin. In this study the spring and summer bird use of Willamette Basin revetments is examined. Revetments that had not been recently cleared of most woody vegetation and blackberries were found to have significantly greater total and breeding bird use than cleared revetments. Possible factors affecting bird use, such as vegetation on revetments and vegetation adjacent to revetments are examined using linear regression analysis. The results of this study are compared with results of previous work in riparian forests along the Columbia River. It is concluded that revetments represent significant avian habitat, especially for "edge species," and that present maintenance practices involving removal of vegetation adversely affect bird use.

Chewings fescue [Festuca rubra L. subsp. fallax (Thuill.) Nyman] is a desired turfgrass with dense sod forming capabilities and superior shade tolerance. Thermal residue management (open-field burning) has traditionally been used to remove post-harvest residue and maintain seed yield over the life of the stand. However, alternative non-thermal residue management practices have been observed to produce adequate seed yields dependent upon cultivar. Strong creeping red fescue (F. rubra L. subsp. rubra) is desired for its prolific tillering capacity and creeping rhizomatous growth habit. In contrast to Chewings fescue, maintenance of seed yield in strong creeping red fescue has only been profitably produced under thermal residue management. Slender creeping red fescue [F. rubra L. var. littoralis (Vasey)] is a desired turfgrass with a compact, less rhizomatous growth habit, similar to Chewings fescue in desirable turf attributes. However, little is known about the effects of post-harvest residue management in slender creeping red fescue. The objectives of this study were: 1) to evaluate seed yield and yield components among different cultivars to thermal (open-burning), and non-thermal (flail low and flail high) post-harvest residue management; 2) to evaluate harvest index and percent cleanout to thermal and non-thermal residue management in different cultivars; and 3) and to provide an economic analysis of thermal and non-thermal residue management in all cultivars based on partial budgeting. Three post-harvest residue management treatments (burn, flail low and flail high) were applied over the course of two years. Seed yield components measured included: total dry weight, fertile tiller number, spikelets per panicle, florets per spikelet, and panicle length. Final seed yield in each cultivar and residue management treatment method was determined after seed harvest and conditioning. Seed yield component analysis was conducted over three production seasons. Chewings fescue, strong creeping red fescue, and slender creeping red fescue cultivars responded differently to residue management as indicated by a residue management by cultivar interaction. In 2003 and 2004, residue management by cultivar interactions were evident in seed number, seed weight, fertile tiller number, percent cleanout, harvest index, and seed yield. Residue management by cultivar interactions occurred in spikelets per panicle in 2003, whereas in 2004 a residue management by cultivar interaction occurred in panicle length and florets per spikelet. In 2004, non-thermal flail low, and thermal residue management resulted in significantly greater spikelets per panicle in all cultivars. Thermal residue management resulted in the greatest number of spikelets per panicle. Results indicate that thermal residue management best maintained seed yield in most subspecies and cultivars across both years. However, in 2003, non-thermal flail low residue management produced profitable seed yield in only Marker slender creeping red fescue. In contrast, thermal residue management resulted in poor seed yields in Marker slender creeping red fescue and enhanced yields in Seabreeze slender creeping red fescue in 2003. However, following the second year of thermal treatment in 2004, Marker and Seabreeze both had lower seed yields, thus exhibiting the only negative impact of thermal management among the cultivars tested in this study. Moreover, upon review of an economic analysis, Marker slender red fescue was the only cultivar that produced a positive net return of $78 and $4 ha⁻¹ under non-thermal residue management in 2003 and 2004, respectively. Furthermore, in 2003, thermal residue management net return increases ranged from $104 ha⁻¹ to -$996 ha⁻¹ in Barnica and Shademark, respectively. In 2004, thermal residue management net return increases ranged from $115 ha⁻¹ and $1,332 ha⁻¹ in Seabreeze and Shademark, respectively. Poor seed yields were observed in all strong creeping red fescue cultivars under non-thermal residue management across both years of the study. This may be attributed to an observed reduction in fertile tiller number and seed yield. In addition, percent seed cleanout was increased with non-thermal residue management. In 2004, as stand age increased, thermal residue management resulted in greater seed yields in all cultivars and species, except both cultivars of slender creeping red fescue. Thus, this study provided substantial evidence that thermal residue management has the potential to maintain or increase fine fescue seed yield as stands age as well as to maintain stand profitability. / Graduation date: 2005

There are two major problems associated with soil acidity and lime response investigations: A. Determining how much lime (100% "available" CaCO��� equivalent) is required to raise a soil pH (or degree of acidity) from its existing level to a specified level - presumably where need for lime is eliminated. B. Determining responses of different crops on different soils to lime; and defining some chemical measurement of the soil that will predict the response of a specified crop. Investigations in this study were limited to the first problem. Liming characteristics of 45 acid Willamette Valley soils, representing the major agricultural soil associations, were determined by incubating the soils with increments of CaCO���. The lime required to bring the soils to the specified pH levels of 6.8, 6.4 and 6.0 varied widely within the respective pH levels. Relationships between soils, however, as determined by the value of the incubation curve slope (meq. of CaCO��� /100g of soil required to raise soil pH by one unit), were improved by grouping into related soils. Laboratory measurements of other soil chemistry parameters were compared with changes in pH to determine if a satisfactory quick laboratory procedure could be developed to measure the incubation lime requirement of soils with different chemical characteristics. Measurements of soil pH were made by three different methods: (1) in the supernatant of a 1:2 soil to water suspension; (2) in the sedimented paste of the 1:2 soil to water suspension; and (3) in the supernatant of a 1:2 soil to 1 N KCl suspension. Lime requirement with a buffered solution was measured in limed and unlimed soils by use of the SMP (Shoemaker, McLean, and Pratt) buffer method. Soil samples treated with increments of lime were analyzed for extractable Al and exchange acidity by titration and the unincubated soils were analyzed for exchange acidity determined by subtracting exchangeable bases from CEC measured at pH 7. 0 and pH 6. 0. Results of the correlation analyses showed that the SMP buffer method should prove useful for predicting the incubation lime requirement. Correlation coefficients for these two values were .89, .90 and 86, respectively, to reach pH levels of 6.8, 6.4 and 6.0. Soil pH measurements, extractable Al, and exchange acidity determinations did not provide as good a basis for determining incubation lime requirements, Regression equations were calculated for the SMP buffer/incubation lime requirement relationships. The purpose of this study was to identify the changes in soil chemical measurements that take place with application of lime. No attempt was made to determine whether a crop might respond to an application of lime on an acid soil. The assumption was made that yield could be related to specific pH or soil acidity levels that could be measured in the laboratory. Therefore, the problem was approached by studying procedures that might determine the application of lime required to reach a specified pH or soil acidity measurement. It anticipated that field trials for evaluating lime response will be carried out in the future to evaluate the usefulness of the SMP buffer method which showed promise in this regard. / Graduation date: 1972

Thesis (M.S.)--Oregon State University, 1971. / Partially funded by Oregon Agricultural Experiment Station. Includes bibliographical references (leaves 39-41). Also available on the World Wide Web.

Graduation date: 1997

Thesis (M.S.)--Oregon State College, 1952. / Typescript. Includes bibliographical references (leaves 120-121). Also available online.

Thesis (M.S.)--Oregon State University, 2000. / Typescript (photocopy). Includes bibliographical references (leaves 80-82). Also available on the World Wide Web.

Originally presented as the author's Thesis (M.A.--University of Oregon). / Includes bibliographical references (p. 54-55). Also available on the World Wide Web.