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  • Author or Editor: Harrison Hughes x
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Stevia (Stevia rebaudiana Bert.) leaves produce stevioside and rebaudioside that can be used as a natural source of low-calorie sweetener which is heat-stable. Because of low fertility, this plant is often vegetatively propagated for field production. This study was conducted to optimize tissue culture procedures for propagating selected clones and explore the feasibility of producing the sweetener compounds by callus cultures. Shoot proliferation was best in Murashige and Skoog (MS) medium supplemented with 0.1 mg/l naphthaleneacetic acid (NAA) Plus 10 mg/l kinetin. Kinetin as a cytokinin source was better than benzyladenine (BA) especially when NAA was present. Callus production fronm leaf disc cultures was most prolific when a combination of 0.1 mg/l NAA and 3 mg/l BA was used in MS medium. The relative sweetener contents of callus cultures are currently being-analyzed.

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An assessment plan for the Horticulture and Landscape Horticulture majors has been developed as part of a university-wide effort to assess resident instruction. The program mission has been described as the preparation of graduates with a passion for Horticulture/Landscape Horticulture who can contribute to Colorado's agricultural and green industry economy through high levels of: 1) technical competency and skills, including disciplinary competence, and a working knowledge in the appropriate field; 2) management and leadership skills; and 3) problem-solving skills. Assessment methods involved the development of evaluation forms for internships, practicum, independent study, group study, and the capstone courses. Student, faculty, clients, and industry personnel used standardized forms, which varied somewhat for the two majors and seven concentrations, to critically assess and score student and faculty efforts. Internships, practicum, and capstone courses were evaluated for program purpose. The management and leadership skills of the students were evaluated based on their performance during internships by cooperators and also by their activities, as demonstrated through their involvement in university, college, departmental, and community activities. Problem-solving skills were evaluated primarily through student performance in capstone courses, with specific criteria in the internship and in leadership activities of clubs. The expectation is that 70% to 75% of the students will score 3 or 3+ on all criteria established for a rating system of 1–5. Students have generally met this standard and plans are under way to continually upgrade courses and related activities to improve the teaching program

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The influence of storage temperature and length of time in storage on anthocyanin tuber concentration were investigated in seven potato genotypes. These genotypes were cultivars `All Blue' and `Yukon Gold' plus five selections that were various skin/flesh color types of red/red, purple/purple, white/yellow, and two red/yellow types. The red, blue, and purple colors are the result of various anthocyanin compounds. Tubers of the seven genotypes were stored at 4.4 or 10 °C for 0, 4, 6, 8, 10, 12, 16, 20, or 24 weeks. Both fresh and freeze-dried samples of the tubers were evaluated for each temperature and time treatment combination. Extractable anthocyanins were found in only the three pigmented genotypes red/red, purple/purple, and `All Blue'. Anthocyanin concentrations were estimated spectrophotometrically with a Molecular Devices Spectramax 384, based upon extinction coefficients reported in the literature for purple and red pigmented potatoes. Anthocyanin concentration increased in storage as time in storage increased for both fresh and freeze-dried samples. Tubers stored at the cooler temperature (4.4 °C) had higher levels of anthocyanin than those tubers stored at the higher temperature (10 °C). Increased levels of anthocyanins in cold-stored tubers may be linked to the conversion of starch to sugar (so called cold sweetening) known to occur at cold storage temperatures. Pigment extraction was more efficient from freeze-dried tuber samples compared to fresh tuber samples. There was, however, a similar increasing trend in both freeze-dried and fresh tuber sources with storage duration.

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Carbonated water (CW) application has enhanced yields of tomato. However, little is known about the mechanism of this response. Our objectives were to determine if strawberry would respond to CW application and the effect of soil pH modification on the expression of a yield response. Two different soils were used; a calcareous soil (5% CaCO3, pH 7.9), with a Zn content 0.8 ppm and a non-calcareous soil (< 1% CaCO3, pH 6.5) with a Zn content 8.8 ppm. The carbonated water temporarily lowered the pH of the calcareous soil to 6.7 and the non-calcareous soil to 5.9, at both extremes of the optimal range (6.0-6.7) for strawberry. Application of carbonated water increased production of marketable fruit as compared to the tap water control on both soils, and the magnitude of the response to CW was similar for both soils. Soil and water treatment effects on leaf tissue Zn levels will also be discussed.

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