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- Author or Editor: Harrison Hughes x
The food crop concentration in the horticulture major was revised in response to discussions with students, faculty, and county agents to emphasis more service learning. A requirement for an internship or practicum was added. The practicum entails the design, maintenance, and data collection of the vegetable and small fruit display gardens. Emphasis will be on sustainable production and on collection of information for use in extension fact sheets for the citizens of Colorado. Other changes include the modularization of the commodity courses to provide greater flexibility and the addition of a capstone course. The capstone course will involve greater interaction with industry in the state and has a requirement for the development of both an enterprise budget as well as a production plan for a commercial operation.
Colorado State Univ. recently underwent the development of a new all university core curriculum. All faculty were encouraged to submit proposals for new courses or revised courses, which would be reviewed for inclusion under specified categories. Basic Horticulture was redesigned te emphasize the scientific method, the understanding between science and society, and the use of handson and inquiry-based instruction in the laboratory. Horticultural Science is now an applied science course that includes the use of hypothesis formulation, experimentation, observation, data collection, summation and presentation in scientific format of reports of at least three laboratory exercises, as well as extensive general observation and presentation in both written and oral format. It teaches science in the context of everyday interaction with the environment in which the student lives, the interior and exterior plants that surrounds the student at CSU, and the controversies as well as the health aspects that surround the production of foods derived from plants that require intensive cultivation. Examples of such issues include sustainability, the organic movement, genetically modified organisms, ground water pollution form overfertilization, and water usage for landscaping and golf courses in a water short region. A review of the revisions as noted above and the use of technology in teaching the course will be presented.
Internship credit has been offered for nearly 30 years. In more recent years, it has been formalized with specific guidelines developed in setting up an individual student program. Internship opportunities are facilitated through a career day, which has moved from fall to spring semester in which over 25 firms come on campus to present their opportunities. A detailed packet of information is distributed to the perspective intern and cooperator. A memorandum of agreement is developed with student, cooperator and internship coordinator which details credit, description of the program and hourly wage. Students are required to submit weekly reports and upon returning to campus must present an oral report to a student group and a written report to the internship coordinator. The cooperator does a summary evaluation, which is submitted to the coordinator. A final interview with each student is done with the internship coordinator and a S/F grade is assigned.
Detached and intact leaves (first fully expanded leaf from the top) of tobacco (Nicotiana tabaccum L.) plantlets hardened in vitro with 2.0% polyethylene glycol (PEG) showed increased diffusive resistance (r) over those of nonhardened plantlets as measured by a steady state porometer. The leaves of the PEG hardened plants maintained a higher resistance throughout the one hour dessication period in approximately 30% relative humidity although both treatments showed an increase in diffusive resistance after 30 minutes. This indicates that the stomates are functioning in the in vitro tobacco plantlets. The higher (r) in the PEG treated plants may be due to more complete closure of stomates, higher cuticle wax content or a combination of both.
Grape cv. Valiant was micropropagated in an MS medium with and without 2% (W/V) of polyethylene glycol (PEG, MW 8000). Leaf anatomy of control (in vitro, no PEG), treated (in vitro, PEG), field grown and greenhouse grown plants were compared under light microscopy. Cell size, palisade layer formation, relative intercellular air space and apparent chloroplast number varied between the leaves of control and PEG treated (high osmoticum) plantlets. These leaf characteristics in the high osmoticum medium appeared more similar to the leaves of the greenhouse and field grown plants. Leaves from control plantlets contained cells of larger size, lacked normal palisade layer formation, greater intercellular pore spaces and fewer chloroplasts. Leaves of PEG treated plantlets had smaller cells, a more defined palisade layer, reduced intercellular pore spaces and greater number of chloroplasts. Leaves of greenhouse and field grown plants had small cells, a well-defined palisade layer, least intercellular pore space and greatest number of chloroplasts. These results demonstrate that a high osmoticum medium may be used to induce more normal leaf development.
There are turfgrasses species that are clonally propagated; notably bermudagrass, buffalograss, and zoysiagrass. Some of the early cultivars of these species are no longer widely grown, and may eventually be lost if not preserved. In order to facilitate studies on the long-term cryopreservation of these species and specific lines of saltgrass, it is necessary to develop suitable micropropagation procedures. We have developed protocol for the isolation and establishment of clean cultures in vitro for all four species. A 1/2-strength MS basal medium with Nitsch & Nitsch vitamins, 5 mg/L of thiamine, 2 mg/L of glycine, 30 g of sucrose, 7 g of agar with varying growth regulators has been used. Explant materials are prewashed in the greenhouse prior to a 15- to 30-min soapy wash in the laboratory. After a 30- to 60-min rinse in running water, nodal sections are surface-disinfested in 10% bleach with Tween 20 for 15 min, followed by three sterile water rinses. This procedure, sometimes with PPM (a proprietary antimicrobial compound), results in 50% or greater clean cultures. Rapidly growing nodal sections work best and preferably those not established in soil. We have tested various growth regulator combinations and have found that 10 mg/L of BA results in proliferation of buffalograss and saltgrass. However, proliferation remains relatively slow, requiring 8 to 12 weeks to develop sufficiently for subculture. Although we have succeeded in obtaining clean cultures of bermudagrass and zoysiagrass, proliferation is minimal, Further research is ongoing to develop a proliferative system with these two species.
Watermelon plants are susceptible to Gummy stem blight disease that considerably reduces yields worldwide. In order to develop non-specific resistance, watermelon cv. Crimson Sweet was transformed with copper inducible isopentenyl transferase (ipt), the rate-limiting step in cytokinin biosynthesis, gene via Agrobacterium tumafaciences (LBA4404). Transformed (ipt) and nontransformed plants were grown at approximately 28-30 °C day, 20-22 °C night and 16 hours daylight under greenhouse conditions. Once the plants initiated new growth both transgenic plants and wild type plants were sprayed with one of three different concentrations (0, 10 & 50 μm) of CuSO4. Plants were sprayed twice to run-off in a twenty-four hour time period before inoculation with the pathogen. Cultures of the pathogen Didymela bryonia (W353) were grown for about 3 weeks and an inoculum containing 105 conidia per mL was sprayed with the prepared suspension until initial run-off in a humidified chamber. The disease symptoms were evaluated after one week with resistance demonstrated in all treated transgenic plants. All nonsprayed transgenic and wild type plants showed similar disease symptoms. Infected leaf samples were surface sterilized and re-cultured on V8 medium. The characteristics of the recovered pathogen confirmed that it was identical to the stock culture of W353. The same experiment has been conducted on seedlings from transgenic (T1 generations) and non-transformed plants. The non-transformed seedlings showed the first disease symptoms on their cotyledons and lower leaves. Disease resistance was observed in seedlings of the treated transformed plants as compared to nontransformed ones.
Plantlets of Solarium tuberosum L. `Russet Burbank', `Sangre', and `Centennial Russet' were grown in vitro from nodal cuttings. A medium overlay was used to reduce the humidity of the in vitro environment. This treatment was tested for its effect on plant growth and on the rate of water loss from detached leaves. The latter was assayed as indicative of hardening and consequent survival of plantlets once removed from in vitro culture. The paraffin medium overlay reduced the rate of water loss from detached leaves of cultured plantlets, but also reduced root growth.
The watermelon cv. Crimson Sweet was transformed with the copper inducible isopentenyl transferase, the rate-limiting step in cytokinin biosynthesis, gene via Agrobacterium tumafaciences (LBA4404). Transformed (ipt) and nontransformed plants were regenerated from tissue culture and clonally propagated by the rooting of leaf node cuttings. Twelve plants of each were grown in 1-gal. pots. Once the plants initiated new growth both transgenic plants and wild type plants were sprayed with one of four different concentrations (0, 5, 10, & 50 μm) of CuSO4. The experimental unit was a single plant with three replicates. The growth rate, number of leaves, flowers, lateral shoots, and chlorophyll content were measured weekly for five weeks. Treated transgenic plants had greater numbers of leaves, flowers and lateral branches as well as higher chlorophyll levels. Pollen viability was examined in all treatments with no differences among treatments. Plants of both types were self pollinated to generate seeds. Female flowers were bagged before opening and then selfed. Selfed flowers were bagged for at least two days. The fruits were grown for eight to ten weeks with support. Once they reached maturity, fruits were harvested and fruit shape, flesh color, brix, number of normal seeds, number of colored but empty seeds and number of white seeds were recorded. Significant differences were observed only in seed number between wild type and transgenic (both treated and nontreated,) watermelon fruits. The number of seeds in transgenic watermelon plants treated with CuSO4 was reduced to about 5% to 7% of wild type plants. Transgenic plants which received no CuSO4 had approximately 33% to 50% of the seed of wild type.
`Crimson Sweet' watermelon was transformed with a copper inducible ipt gene. Clonally propagated transformed and non-transformed plants were sprayed with three different concentrations (0, 50, 100 mm) of CuSO4 at the 2–3 leaf stage twice in a 24-hour period prior to their inoculation with fusarium wilt organisms. Plants were inoculated via root dip with two different isolates of Fusariumoxysporum sp. niveum Race 2. The pathogenic strains of Fusariumoxysporum sp. niveum Race 2, Fl 99-1, and Calg 15-19, were cultured on PDA solid medium and then transferred to a sterile flask filled with 50 mL of potato dextrose broth (PDB) liquid medium. These flasks were placed on a shaker at 100 rpm for 4–5 days before the inoculation date and the final concentration of 106 spores/mL was adjusted for inoculation. Roots of the experimental units were gently washed and were then infected by dipping them in to the beaker containing the isolates for 1 min. Inoculated plants were transferred to planting trays and maintained under growth chamber conditions. Plants then were watered as needed. Fusarium wilt symptoms initially appeared approximately 7–10 days after the infection. The Cu-ipt transformants exhibited a clear and significant resistance over non-transformed plants. The severity of disease development was relatively higher in the control Cu-ipt and non-transformed plants when compared to the plants treated with CuSO4. The control Cu-ipt plants were comparatively healthier than the control non-transformed plants. Infected plants were removed from soil 2 weeks after inoculation, washed and the stems were cut vertically for rating of browning of the vascular system.