You are looking at 1 - 10 of 18 items for
- Author or Editor: Steven C. Wiest x
The process of ice formation in media at container capacity was followed by sectioning the frozen medium and determining solute content in each sample using sodium fluorescein as a tracer. H2O apparently moved from the bottom and central interior regions of the container medium to the sides of the container. The phase in which movement occurred is unknown. Fluorescein moved down from the top and central interior regions to the bottom and sides of the container. The final distribution of fluorescein should indicate the location of the majority of liquid H2O due to the exclusion of solutes by ice. In the partially frozen state the greatest amount of liquid water therefore occurs near the container sides – a region normally occupied by a large proportion of the root system.
Digitized photographic images of turf plots composed of bermudagrass, buffalo grass, tall fescue, and zoysiagrass were taken at a height of about 150 cm with a 28-mm lens. Fast Fourier transforms of these images were performed, and a radial plot of the power spectrum was obtained from each image. Hurst plots (log frequency vs. log intensity) were used to subtract “background” from the power spectra, so peaks would be more evident. The peak of the power spectrum occurs at the average spacing between leaves (more precisely, between areas of the canopy that reflects a significant amount of light) and defines the characteristic dimension. Zoysiagrass had the lowest characteristic dimension, while tall fescue had the highest. The width of the power spectrum is indicative of the variability of the characteristic dimension within the canopy. The minimum characteristic dimension (occurring at the highest frequency) was less than 1.7 cm, whereas all the other species had about the same minimum characteristic dimension of ≈1.9 cm. The maximum characteristic dimension was greatest for fescue (6.9 cm), followed by buffalo grass (3.8 cm), bermudagrass (3.3 cm), and zoysiagrass (2.8 cm). These results indicate that the characteristic dimension can be a useful tool for discriminating between turfgrass species in digitized images.
A system for the digital analysis of photographic prints of turfgrass plots is being developed. The 3-year-old turfgrass plots included Meyer zoysiagrass, Midlawn bermudagrass, Prairie buffalograss and Mustang tall fescue. The plots were photographed by a camera with a small dual bubble level on the camera back and a 28-mm-wide angle lens. Photographs were digitized with flatbed scanners. The images can then be analyzed in a variety of ways. For example, a series of photographs were taken from mid-Sept. through late Oct 1995 and spectral analysis of the resultant digital images were made. The initial RGB (red-greenblue) format of the images was converted to HSI (hue-saturation-intensity) for analysis. The results indicate, obviously, that hue changed from 104 (i.e., green) to 75.7 degrees (i.e., brownish) between the beginning and end of Oct. 1995. Similarly, intensity changed from ≈0.12 to ≈0.16 during the same time period, indicating that the images became darker over time. These phenomena were observed in all four species examined. However, the saturation value evoked a significant species * date interaction. The three warm-season species showed a decrease in saturation, while Mustang had no significant decrease during Oct. Spectral as well as textural analysis are likely the two most useful techniques in the digital analysis of turfgrass plots. Examples of both will be presented.
Scanning electron micrographs of grape berry surfaces, which resemble mountainscapes, contain a wealth of structural information. A typical statistical characterization of features such as root mean square peak-to-peak spacings, peak density, etc., is readily performed on these images. However, a much richer base of information is accessible by analyzing the images with fractal geometry. Fractal box dimension is a quantitative measure of surface roughness, and varies with the contour at which it is determined in both cultivars `Foch' and `Perlette', suggesting that the surfaces are multifractal structures. Fourier spectral analyses of the surfaces produce a similar conclusion. Thus, the unambiguous quantitative resolution of cultivars on the basis of their wax surface structure looks promising, but requires further work.
The prediction of which species will do well in various microclimates is of obvious interest to horticulturists as well as homeowners. To this end, the following 5 species of trees and shrubs where planted at 5 disparate sites across Kansas in spring 1985 and growth and environment measured for the 4 following years: Phellodendron amurense, Acer rubrum, Acer platanoides `Greenlace', Quercus acutissima, and Cercocarpus montanus. Preliminary analysis of trunk diameter growth vs. environment indicates few simple relationships and several rather complex relationships. Rather simplistic linear relationships (growth vs. a single environmental parameter) are largely meaningless, and often misleading. For instance, growth of Q. acutissima was negatively correlated with the highest maximum temperature prior to the growing season and positively correlated with the lowest minimum temperature prior to the growing season. More complex, and reasonable, relationships will be presented.
The possibility that low cellular concentration of sucrose was limiting the expression of hardiness in young roots of Pyracantha coccinea Roem. ‘Lalandii’ Dipp. was investigated. While the sucrose content of young roots increased four-fold following exposure to 4°C, the highest concentration was not higher than that found in non-acclimated mature roots. Attempts to increase hardiness by incubating young roots on sucrose solutions were unsuccessful. However, intracellular sucrose concentrations were not significantly increased by this treatment. Cytochrome oxidase incorporated into a membrane fraction containing plasmalemma vesicles isolated from Pyracantha young roots or from tissue capable of acclimation (Hedera helix L. ‘Thorndale’ callus cultures) was used as a probe for architectural alterations of this membrane following exposure to 4° and 5°. The apparent first order rate constant of the cytochrome oxidase reaction was used to indicate membrane fluidity. Above the Arrhenius discontinuity, membrane fluidity in both species was greatest when plants were grown at 4° or 5°. However, below the Arrhenius discontinuity fluidity remained greater in ivy callus grown at 5°, but not in Pyracantha young roots exposed to 4°. Altered properties of the membrane surface, inferred from the second order rate constant, were observed only in plasmalemma of young roots. Several possibilities to account for the lack of young root hardiness are presented.
The influence of root and shoot pruning on the growth of transplanted 3-year-old Ilex crenata ‘Convexa’ × I. crenata ‘Stokes’ was determined under various backfill regimes. Root pruning reduced shoot dry weight increment 24% but only reduced root dry weight increment 6%. Root pruning caused water deficits to develop which can quantitatively account for the reduced shoot growth. Shoot pruning reduced root dry weight increment without influencing shoot dry weight increment. Adjustments of the means for altered tissue water content caused by shoot pruning resulted in decreased root and shoot dry weight increment. Root and shoot pruning influenced plant growth directly — by influencing growth mediating processes, and indirectly — by influencing plant water relations. Root growth was influenced primarily by growth mediating processes while shoot growth responded to both growth mediating processes and plant water relations.
Stems and leaves of Pyracantha coccinea Roem. ‘Lalandii’ Dipp. acclimated to —26°, and mature roots to —17°, when previously exposed to 4° for 5 weeks. Young roots, however were killed at —5° even after exposure to 4° for 16 weeks. Differential thermal analysis was used to determine whether the initial freezing processes were altered following exposure to 4°. A higher percentage of tissue water was frozen during the initial period of ice formation in young roots grown at 18° than those grown at 4°. No difference in the percentage of tissue water frozen in mature roots grown at either 18° or 4° was evident. The rate of ice formation in both young and mature roots was highest in tissues grown at 18°. Thus, after exposure to 4°, the physical stresses in root tissue due to ice formation were decreased in both young and mature tissue. While growing the tissue at 4° alters the physical stresses imposed by ice formation, young roots do not survive below —5° whereas mature root roots do. Therefore, it is suggested that differences in survival of mature and young roots of pyracantha are not solely due to a mitigation of the physical stresses imposed by ice formation.