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  • Author or Editor: Harrison Hughes x
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Previous studies have shown that liquid medium additions on established cultures enhance shoot growth and proliferation. In the present report, the growth and multiplication of apples and grapes were evaluated after the addition of liquid media to established cultures. Grapes and apples were micropropagated on agar solidified nutrient medium with 5μM BAP, and 4.4μM BAP, 1.4μM GA, 4.9μM IBA, respectively. A liquid overlay of similar medium was added after 4 to 6 weeks in both cultures. Improved growth, number of shoots, and a reduction in callus growth were observed in both species as compared to shoots transferred to fresh solid media. The number of micropropagated apple shoots and their height increased significantly by 35% and 69% respectively. Proliferation of grape shoots increased by 198% while callus growth decreased by 64% when compared to cultures transferred to fresh solid media.

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Abstract

A disorder of red raspberry (Rubus idaeus L.) in an area exposed to high temperature and solar radiation has been identified as a form of solar injury. Specific fruit maturity stages were defined and susceptibility to injury was found to rapidly increase as fruit matured from the “green” to the “white” to the “pink” stage. Appreciable injury (more than two unpigmented drupelets per fruit) only occurred at 42C and higher with 4 or more hours of UV radiation at the fluence level used. While the injury at 42C was proportional to UV exposure, the radiation environment in the laboratory was not designed to simulate solar radiation. Therefore, no quantitative function relating injury to fruit temperature and UV radiation is presented. The results indicated that attenuating UV absorption alone, without lowering temperature, is likely to protect raspberries in the field.

Open Access

After 6 months of growth in 200,400, and 500 mm NaCl, cultured cells of Distichlis spicata showed a decreased cell volume (size) despite maintenance of turgor pressure sometimes 2-fold higher than that of the control. Tensile strength, as measured by a nitrogen gas decompression technique, showed empirically that the walls of NaCl-stressed cells were weaker than those of nonstressed cells. Breaking pressures of the walls of control cells were ≈68 ± 4 bars, while that of the walls of cells grown in 500 mm NaCl (-25 bars) were 14 ± 2 bars. The relative amount of cellulose per cell remained about constant despite salt stress. However, glucuronoarabinoxylans were more readily extractable, presumably because of a decrease in cross-linkage with phenol substances. Therefore, we suggest that cellulose microfibrils are not the only determinants that confer tensile strength to the primary cell wall, but rather subtle changes in the matrix polysaccharides are likely responsible for this event.

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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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Buffalograss (Buchloë dactyloides [Nutt.] Engelm.) is adapted for use as a low maintenance turf in much of the semi-arid West. New cultivars with improved turf characteristics are being developed and released, but little information quantifying either relative tolerance or variability among germplasms to salt stress is available. An in vitro procedure was used to characterize seedling growth response to additions of 0-300 mol m-3 NaCl in 50 mol m-3 increments in media containing MS basal salts solidified with 0.6% agar. Germinated seeds of cultivars Sharp's Improved, Texoka, Topgun, and Plains transferred to treatments were evaluated after 40 d growth. The threshold for decline in shoot dry matter vs control was 50 mol m-3 NaCl for all cultivars. An average 50% shoot dry matter reduction vs controls across cultivars was found at 150 mol m-3 NaCl, affecting leaf length but not survival; shoot [Na+] ranged from 9.12 - 9.86 mg g-1 dry matter. Survival was severely affected at 250 mol m-3 NaCl. Cv. × NaCl interaction was significant.

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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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Carbonated water has recently been under study as a potential means of increasing photosynthesis in the field situation. Cahn (1989) and Novero (1991) have demonstrated that carbonated water lowers soil pH in strawberries and tomatoes, respectively. Novero showed greater uptake of zinc and increased marketable fruit yields. Currently, we are evaluating the influence of carbonated water on strawberry (Fragaria × ananassa cv Muir) growth using a high pH, high calcium soil and a low pH, low calcium soil in the greenhouse. Carbonated water applied to a high pH, high calcium soil significantly increased leaf, bud and open flower number, as well as greater crown and leaf dry weights.

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