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Virginia P. Roxas and Ellen B. Peffley

Nineteen random primers yielded 36 PCR-amplified products of Allium cepa profiles of each of 15 short-day grano-type onionsgrown commercially in Texas and Southern United States were compared. Several PCR productswere unique among the cultivars and can be used to differentiate among the onion cultivars investigated. A phenogram of the cultivars based on the co-occurrences of the PCR products was derived.

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Ruwanthi C. Wettasinghe and Ellen B. Peffley

Random amplified polymorphic DNA (RAPD) have potential as genetic markers that may facilitate selection in plant improvement. To obtain clear, reproducible, and repeatable RAPD bands, four DNA extraction protocols and two Taq polymerases were compared. DNA extraction followed modified Tai and Tanksley (PMBR), Dellaporta et al. (PMBR), and Guilllemant et al. (PMBR) protocols, and a plant tissue DNA isolation kit from Gentra Systems was used. The modified Guillemant protocol was selected because of ease of extraction and cost effectiveness. Genotypes studied were TG1015Y (Allium cepa). Polymerases compared were Taq and Taq Stoffel fragment. Results are based on separate amplifications and electrophoretic assays. PCR amplifications of Stoffel fragment produced more scorable and reproducible RAPD bands compared to bands produced using Taq polymerase.

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Ruwanthi C. Wettashinghe and Ellen B. Peffley

Random amplified polymorphic DNA (RAPD) are genetic markers that facilitate selection in plant breeding. To obtain clear reproducible, and repeatable RAPD bands, four DNA extraction protocols and two Taq polymerases were compared using thirteen TG1015Y (Allium cepa) genotypes. Protocols for DNA extraction followed those of a modified Tai and Tanksley, 1989 (PMBR); a modified Dellaporta et al., 1983 (PMBR); a modified Guillemunt et al., 1992 (PMBR); and extracted with a plant tissue DNA isolation kit from Gentra System (Minneapolis). The modified Guillemunt protocol was selected due to ease of extraction and cost effectiveness. Polymerases compared were Taq and Taq Stoffel fragment. Results are based on three separate amplifications and electrophoretic assays. PCR amplifications of Stoffel fragment produced more scorable and reproducible RAPD bands compared to bands produced using Taq polymerase.

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Ellen B. Peffley and Chad S. Davis

The concept that plants and humans in a living system are mutually beneficial was communicated to 2nd to 12th grade students in science educational and outreach programs at Texas Tech University's Center for Space Science. Students traveled to the TTU horticulture greenhouse for a live program, which focused on research in the Engineering Development Unit. The research is funded by NASA's Advanced Life Support. During the program students were presented with the science of growing plants, how plants benefit humans in space, and baseline science vocabulary. A survey instrument was developed to assess student level of understanding of sciences, and their comprehension of living cycles, which work together to support manned space missions. The survey consisted of multiple-choice questions covering topics presented during the program. Likert questions were used to assess student's desire to travel in space, be an astronaut or a scientist, and their enjoyment of science and growing plants. The survey was administered before the program; immediately after the program; and a delayed test was administered in their classroom several weeks after the program. Student performance was scored according to correct responses in the survey. Responses were analyzed for changes over time using an analysis of variance with repeated measures. The results showed there was an overall improvement in knowledge from preprogram survey to postprogram survey and that students recognize science is the main topic to be studied to expand for better space programs. Some elementary education students scored equal to or higher than secondary education students. Enthusiastic science teachers may drive student interest exhibited in the early grades. There is evidence that a teacher's attitude towards science and one's basic science knowledge is important to molding student's attitudes and interests in science.

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Paul D. Mangum and Ellen B. Peffley

The inheritance and linkage relationships among PGM-1, ADH-1, and 6-PGDH-1 were determined for Allium fistulosum (Japanese bunching onion) individuals. Individuals expressing Pgm-11/Pgm-12, Adh-13/Adh-14, Adh-13/Adh-15, or 6-Pgdh-11/6-Pgdh-12 were selfed seperately. These backcrosses and their reciprocals were made: Pgm-11/Pgm-12 to Pgm-11/Pgm-11 or Pgm-12/Pgm-12; Adh-13/Adh-14 to Adh-13/Adh-13 or Adh-14/Adh-14, 6-Pgdh-11/6-Pgdh-12 to 6-Pgdh-11/6-Pgdh-11 or 6-Pgdh-12/6-Pgdh-12. Progeny segregations were tested for Mendelian inheritance using a chi-square goodness of fit test. Expression of 6-Pgdh has not been previously reported in onion. Two zones of activity were detected and were designated as 6-PGDH-1 and 6-PGDH-2. 6-PGDH-2 was monomorphic for all individuals tested. Progeny segregation of 6-PGDH-1 fit a model for a dimeric enzyme encoded by one disomic locus with two alleles, expressed as fast (1) and slow (2), in a dimeric enzyme pattern in heterozygous individuals.

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Paul D. Mangum and Ellen B. Peffley

Horizontal starch gel electrophoresis was used to study the inheritance of isozyme phenotypes of four enzyme systems [alcohol dehydrogenase (ADH), 6-phosphogluconate dehydrogenase (6-PGDH), phosphoglucomutase (PGM), and shikimate dehydrogenase (SKDH)] in Allium fistulosum L. by monitoring segregations in backcross and F2 progeny. Segregation for most of the polymorphisms fit the expected Mendelian ratios as tested by the chi-square statistic. Three new isozyme loci were defined for onion. Two loci were found for 6-PGDH. Locus one was dimeric with two alleles, and locus two was monomorphic. SKDH was monomeric with two alleles.

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Amanda L. Broome and Ellen B. Peffley

This research evaluated, for the NASA ALS program, the effect of spacing and harvest intervals on edible biomass of green salad onions grown at two CO2 levels. Shoot biomass of Japanese bunching onion (Allium fistulosum), bulbing onion (A. cepa), and chives (A. schoenoprasum) grown at 10-, 15-, and 20-mm spacings harvested at 7- and 14-day intervals, seven and four harvests, respectively, over 70 days were compared. Onions were grown hydroponically in growth chambers, 16-hour light/8-hour dark, 24/20 °C, 75/99% at ∼450 and 1200 ppm CO2. The design was a completely randomized block with repeated measures; subsamples were plants completely surrounded by neighboring plants. Weekly shoot removal began 28 days after planting (dap); destructive harvest was 70 dap. Length and diameter of longest leaf, weight, and number of leaves/tillers were taken at each harvest; bulb caliper and weight were taken 70 dap. Bunching and bulbing onion leaves were longest at 28 dap and decreased over time; chives were slow to establish but 70 dap had longest leaves. Leaf diameter of all species increased as spacing increased. At 56 through 70 dap chives at all three spacings produced more leaves. Mean weight of shoots differed significantly at 20-mm spacing: chives the least, bulbing onion the most. Bulb weight for bulbing onion and chives increased with increased spacing; bulbing onion weighed significantly more at 15- and 20-mm spacings compared to the other species and spacings. Chives grown at 20-mm spacing had tillering clumps of rhizomes. Total edible biomass weight (bulb, pseudostem, and shoots) of bulbing onion grown at 10-mm spacing exhibited similar ontogeny to chives grown at 10- and 15-mm spacings; bulbing onion grown at 20-mm spacing had the most edible biomass. On average, biomass was greatest in plants grown at 1200 ppm CO2.

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Igino Teolis, Ellen B. Peffley, and David B. Wester

A study was conducted to evaluate student performance after receiving the same horticultural lesson through one of two modes of instruction. Students enrolled in an introductory horticulture course received either a traditional herbaceous plant identification (ID) lesson with live plant specimens or the same lesson using only text and photographs on the Internet in one of their laboratory sessions. A follow-up experiment was conducted in which web-based students studied photographs of the exact same plants studied by students receiving traditional instruction. Learning style preferences and demographic information were obtained from surveys. For both experiments, students receiving traditional instruction had higher scores on the plant ID quiz than web-based students. All students were able to identify plants from photographs just as well as from live plant specimens. Visual learners scored higher when receiving traditional instruction when compared with web-based instruction. Student grade point average was positively correlated with quiz score for both experiments.

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Cynthia B. McKenney, Ellen B. Peffley, and Igino Teolis

Increasingly more collegiate courses are offered through a variety of distance formats. Course management platforms have reduced the faculty time required to create and deliver distance courses while enhancing asynchronous communication. In this study, the transactional distance theory was used to evaluate the different communication levels found between faculty and students in web-facilitated, online, and interactive video courses. A comparison of the online course sections to the web-facilitated course sections determined that there were significantly more asynchronous contacts with the online sections than with the web-facilitated sections. In addition, the total instructor time invested to administer the online course sections was significantly less than for the web-facilitated course sections. The interactive video conferencing sections could not be compared directly to the other teaching modes because the course content differed; however, mean time intervals for teaching and administrative activities are provided.

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Agnes RICROCH, Robert J. BAKER, and Ellen B. PEFFLEY

Biotin- and fluorescein-labeled probe has been used to map. specific sunflower rDNA sequences by in situ hybridization on mitotic chromosomes of Allium cepa, Allium fistulosum and interspecific hybrid derivatives, There are three hybridization sites in A. cepa and more than six in an interspecific triploid. This in situ hybridization technique offers new cytogenetic markers useful in the construction of a physical genomic map of Allium and offer a means to document introgression of these genomes.