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Texas is botanically diverse with approximately 5500 native plants identified: east Texas contains about 40% of the total. While most species are stable, many are classified as rare, threatened, vulnerable, or endangered. Databases for east Texas plant communities and vegetative analyses are numerous. However, they are not yet integrated into easy-to-sort-and-query computer files. Computer-Assisted Drafting (CAD) and Geographic Information Systems (GIS) technology offers powerful applications to the storage, management, and spatial analysis of species inventories, plant community dynamics, and long-term habitat monitoring. At SFASU, the College of Forestry's GIS Center is being utilized to develop comprehensive east Texas resource inventories on a ten-station HP Apollo/ArcInfo platform. In the horticulture program, a twenty-station PC/AutoCad teaching laboratory is being used to create layered maps of the SFASU Arboretum, the on-campus landscape and off-campus plant communities. The integration of CAD and GIS projects through a DXF format takes advantage of the attributes of both technologies.
This paper outlines the history of the SFA Arboretum's effort to establish a campus-as-arboretum at the university. In 1996, the participants created a robust Geographic Information System (GIS) for the campus forest based primarily on a 1993-95 campus mapping and tree inventory project in the 144-acre main core of the campus (Wilson to North St.; College to Starr). The project served as the MS thesis of Susan Perkins. In brief, the campus model reveals a pine-dominated Type 2 forest (one rapidly approaching maturity), difficult campus hydrology issues, and a landscape low on diversity with 68 species represented. In 1996, the Arboretum's AutoCAD® map and Excel® tree data files were integrated into the College of Forestry Unix-based ArcInfo® platform. This now provides full GIS capabilities for landscape planners. The resultant maps based on user queries reveal a robust vegetation analysis and management tool. In 1997, the SFA administration, Physical Plant, Grounds, College of Forestry, and SFA Arboretum initiated a “campus beautification” funding campaign. The SFA Arboretum will play a key role in building unique, documented, and mapped woody ornamental collections for the campus. This provides a unique opportunity in the South for long-term Zone 8 woody plant evaluation in a high-visibility and “perpetual” landscape.
The effect of dehydration stress on membrane competence among and within Fragaria species was evaluated using index of injury, I d , and tissue ionic conductance, g Ti. Single accessions of F. chiloensis ssp. lucida Duch., F. virginiana ssp. glauca (S. Watson) Staudt, F. virginiana ssp. virginiana Duch., F. ×ananassa Duch., and F. vesca L. were used to study interspecific variation. Leaf thickness and total electrolyte content were greatest for the F. chiloensis ssp. lucida accession and least for the F. virginiana ssp. glauca accession, but foliar electrolyte concentration did not vary across accessions. The g Ti values were >5-fold higher from 0 to 2 hours than for other intervals, declining over time. Significant differences in g Ti and I d values were only evident at 2 and 4 hours within stress levels, and increased as stress level increased. While the F. chiloensis ssp. lucida accession exhibited low g Ti values at 70% relative water content (RWC), it showed greater relative membrane injury than the other species expressed as g Ti , I d , or the ratio of stress g Ti to control g Ti as dehydration level increased. Although the F. virginiana ssp. glauca accession had the highest g Ti values, even at 100% RWC, its relative injury as stress level increased was not as great as that of the F. chiloensis accession. In a second experiment, intraspecific variation was examined using four accessions each of F. chiloensis and of F. virginiana which were dehydrated to 50% RWC. The species mean g Ti , I d , and g Ti ratio values at 2 and 4 hours for the F. chiloensis accessions were lower than those for the F. virginiana accessions, but significant intraspecific variation was also observed. In spite of the differences between species means, the evidence of intraspecific variation indicates that not all accessions of a species exhibit similar drought responses (i.e., membrane competence). Due to the consistent conclusions derived from using either g Ti or I d after 2 or 4 hours of incubation for characterization of membrane competence, g Ti and I d were comparable techniques for identification of potential drought tolerance in Fragaria.
Urban landscape ecology is a new interest that crosses several disciplines: botany, forestry, horticulture, sociology and land use planning. University forest environs are often the most degraded; foot traffic, development and a shortage of funds for significant tree plantings are main culprits. SFASU lies in the pineywoods region of east Texas and is known as the “university among the pines.” The campus is blessed with many patriarch pines and hardwoods. Computer-assisted drafting (CAP) and Geographic Information Systems(GIS) platforms are being utilized to map the campus vegetation. A 1992 vegetative analysis, when compared to similar studies in 1971 and 1983, indicates a loss in species diversity and frequency with little change in basal area. AutoCad*, LandCadd*, and Studio-3D* are being integrated into a multi-disciplinary project to develop a three-dimensional biotic/abiotic model of the campus. That model will be used as a “fly-through” visualization tool to develop forest conservation strategies most likely to succeed in a sustainable fashion.
Abstract
The standard ethanol sugar extraction method and a chloroform-methanol-ethanol (CHCl3-MeOH-EtOH) extraction were compared. Determinations of sugar tri-methylsilyl derivatives by gas-liquid chromatography were examined.
The CHCl3-MeOH-EtOH extraction was superior to the ethanol extraction. Complete recoveries of glucose were afforded by both methods; however, the ethanol extraction yielded maltose whereas the CHCl3-MeOH-EtOH method did not.
Deionization of sweet potato sugar extracts and authentic sugars with MB-3 ion exchange resin was undesirable because only small percentages of sugars were recovered.
Discrepancies were found in the recently published determination of sugar trimethylsilyl (TMS) derivatives by gas-liquid chromatography. Although it was reported that the quantity of the TMS product formed was essentially independent of time, at least 6 hr were necessary to completely form the penta-o-trimethylsilyl derivatives of fructose. The penta-o-trimethylsilyl derivatives of glucose were formed within 5 min as indicated in the literature. Anomerization from α- to β-fructose occurred after the introduction of the TMS reactants.
Products of the lipoxygenase/lyase (LOX) pathway such as hexanal, c-3-hexenal, and t-2-hexenal may promote plant pest resistance. The objective of this study was to screen for differences in LOX products among 5 Fragaria species, two selections from each. Volatiles produced upon freezing/thawing leaf disks were measured by capillary GC using a direct headspace sampling technique. The primary volatiles produced were hexanal, c-3-hexenal, and t-2-hexenal. The total yield of each compound and their relative proportions varied among selections. The highest individual yields for hexanal, c-3-hexenal, and t-2-hexenal were observed in F. vesca, F. virginiana, and F. virginiana glauca, respectively. The greatest variation in relative proportion was with c-3-hexenal which ranged from 35% of the total yield in a selection of F. virginiana to 6% in a selection of F. chiloensis. This same selection of F. chiloensis also had the lowest total yield of c-3-hexenal, approximately 25% of the average yield of this compound. F. xananassa produced intermediate yields of the compounds. t-2-Hexenal typically contributed 40-50% of the total yield of each of the screened selections.
Field trials were conducted from 2008 to 2010 to assess the disease reaction to clubroot, caused by Plasmodiophora brassicae Woronin, in selected lines of Brassica spp., including short-season vegetable crops [Shanghai pak choy (B. rapa subsp. Chinensis var. communis)], Chinese flowering cabbage (B. rapa subsp. Chinensis var. utilis), and napa cabbage (B. rapa subsp. Pekinensis), the Rapid Cycling Brassica Collection (RCBC), also known as Wisconsin Fast Plants, and spring canola (B. napus). The trials were conducted on naturally infested soil with P. brassicae at the Muck Crops Research Station in Ontario, Canada, where pathotype 6 is predominant. Clubroot incidence and severity were higher in 2008 and 2010 compared with 2009. The lines of Shanghai pak choy and Chinese flowering cabbage were highly susceptible to clubroot, but each of the clubroot-resistant cultivars of napa cabbage, ‘Deneko’, ‘Bilko’, and ‘Yuki’, was highly resistant to pathotype 6. Among the RCBC lines, B. carinata and B. juncea were highly susceptible and could be used as susceptible models for further studies. Two RCBC lines, B. napus and R. sativus, were resistant to pathotype 6. Two of the canola cultivars, 46A76 and 46A65, were susceptible, but two others, ‘45H21’ and ‘Invigor 5020LL’, were highly resistant to pathotype 6. This difference in response can be exploited in future studies of clubroot reaction in canola.
Field trials were conducted to evaluate resistance to clubroot (Plasmodiophora brassicae, pathotype 6) in green cabbage (Brassica oleracea var. capitata) and napa cabbage (Brassica rapa ssp. pekinensis) at sites in southern Ontario in 2009 and 2010. The reaction of green cabbage cultivars Kilaton, Tekila, Kilaxy, and Kilaherb and the commercial standard cultivars, Bronco or Atlantis, were evaluated on organic (two site-years) and mineral soils (two site-years) that were naturally infested with the clubroot pathogen. In addition, fluazinam fungicide was drench applied to one treatment of the commercial standard cultivar immediately after transplanting. The napa cabbage cultivars Yuki, Deneko, Bilko, and Mirako (in 2009) and Emiko, Mirako, Yuki, and China Gold (in 2010) were evaluated only on organic soils (two site-years). At harvest, the roots of each plant were assessed for clubroot incidence and severity. Also, plant and head characteristics of the resistant green cabbage cultivars were evaluated at one site in 2010. The green cabbage cultivars Kilaton, Tekila, Kilaxy, and Kilaherb were resistant to pathotype 6 (0% to 3.8% incidence), but ‘Bronco’ was susceptible (64% to 100% incidence). Application of fluazinam reduced clubroot severity on ‘Bronco’ by 6% at one of three sites. Resistance was more effective in reducing clubroot than application of fluazinam. Plant and head characteristics of the resistant cultivars were similar to those of ‘Bronco’ treated with fluazinam. Napa cabbage cultivars Yuki, Deneko, Bilko, Emiko, and China Gold were resistant to clubroot (0% to 13% incidence), and ‘Mirako’ was highly susceptible (87% to 92% incidence). We conclude that the clubroot resistance available in several cultivars of green and napa cabbage was effective against P. brassicae pathotype 6.
The expression gti, or tissue ionic conductance, was proposed to describe the efflux of ions from leaf disks (Whitlow et al., 1992, Plant Physiology, 98:198-205). The objective of this study was to determine the effectiveness of the gti method to screen germplasm for heat and desiccation tolerance using representative selections of 5 Fragaria species. Leaf disks were exposed to 4 levels of heat, 25, 35, 45, and 55 C, and 4 levels of desiccation. 60, 70, 80 and 100% relative water content (RWC). F. virginiana glauca was consistently ranked as the leakiest in all treatments including controls, with gti values 70 to 100% higher than in the other species. Temperatures of 25 to 45 C did not influence gti over time. A temperature of 55 C was lethal to the tissue and, thus, the ion flux was initially very high but soon diminished. At 70% RWC F. virginiana glaucu tissue was the leakiest, and F. virginiana and F. vesca tissues were somewhat leakier than those of F. × ananassa and F. chiloensis. Differences among species diminished with time in bathing solutions.
`Keitt' mango (Mangifera indica L.) were kept at 38C for 0, 24, or 48 hours before storage at 5C for 11 days. Nonheated fruit developed severe rind pitting and discoloration, whereas chilling injury symptoms decreased with increased duration at 38C. Respiratory rates were slightly higher in nonheated than in heated fruit. Nonheated fruit produced a transient burst of ethylene evolution following transfer to 21C; heated fruit did not produce a similar burst. Firmness was similar in nonheated and heated fruit at the time of transfer to 21C for ripening, but was slightly higher in nonheated fruit after 3 and 6 days of ripening. Soluble solids concentration was higher in heated than in nonheated fruit at the time of transfer to 21C, but was similar after 9 days at 21C. Commission Internationale de l'Eclairage a* and b* flesh values were higher in heated than in nonheated fruit. Results of this study indicate that mango tolerance to chilling temperatures may increase after prestorage heat treatment.